Non-viral Sexually Transmitted Infections in pregnant women in Primary Care: prevalence and associated factors^*

Objective: to analyze the factors associated with the occurrence of Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium and Trichomonas vaginalis in pregnant women followed up in Primary Health Care.

Method: a cross-sectional study of 302 pregnant women aged between 15 and 49 years. Vaginal secretion samples were collected for molecular biology detection of chlamydia, gonorrhea, mycoplasma and trichomoniasis; a structured questionnaire was applied with sociodemographic, behavioral, obstetric and clinical data, and results of rapid tests (Human Immunodeficiency Virus, Syphilis, Hepatitis B and C). Analysis was carried out using STATA 15.0 software.

Results: the prevalence rates found were: Chlamydia trachomatis (11.6%), Mycoplasma genitalium (9.6%), Neisseria gonorrhoeae (1.7%) and Trichomonas vaginalis (3.6%). Age under 25 (adjusted odds ratio=2.06), presence of symptoms (adjusted odds ratio=1.99), absence of a steady partner or up to one year of relationship (adjusted odds ratio=2.64) increased the chance of having at least one infection.

Conclusion: this study describes the high global prevalence of curable sexually transmitted infections in pregnant women in Primary Health Care. Knowing the prevalence of these infections in pregnant women and the main determinants are essential for reorganizing prenatal care and reducing pregnancy, puerperal and fetal complications.

Descriptors:
Pregnant People; Sexually Transmitted Diseases; Prenatal Care; Primary Health Care; Screening; Prevalence

Highlights:

(1) High prevalence of non-viral STIs in pregnant women. (2) STIs are associated with sociodemographic characteristics and risk behavior. (3) Health education actions aimed at preventing STIs are needed. (4) To support the development of a screening protocol for non-viral STIs in prenatal care.

Objetivo: analisar os fatores associados à ocorrência de Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium e Trichomonas vaginalis em gestantes acompanhadas na Atenção Primária à Saúde.

Método: estudo transversal com 302 gestantes com idade entre 15 a 49 anos. Foram coletadas amostras de secreção vaginal para detecção por biologia molecular de clamídia, gonorreia, mycoplasma e tricomoníase; aplicado questionário estruturado com dados sociodemográficos, comportamentais, antecedentes obstétricos e clínicos, resultados de testes rápidos (Vírus da Imunodeficiência Humana, Sífilis, Hepatite B e C). Análise realizada no software STATA 15.0.

Resultados: as prevalências encontradas foram: Chlamydia trachomatis (11,6%), Mycoplasma genitalium (9,6%), Neisseria gonorrhoeae (1,7%) e Trichomonas vaginalis (3,6%). A idade inferior a 25 anos (odds ratio ajustado=2,06), presença de sintomas (odds ratio ajustado=1,99), ausência de parceiro fixo ou até um ano de relacionamento (odds ratio ajustado=2,64) aumentou a chance de ter pelo menos uma infecção.

Conclusão: este estudo descreve a alta prevalência global de infecções sexualmente transmissíveis curáveis em gestantes na Atenção Primária à Saúde. Conhecer a prevalência destas infecções em gestantes e os principais determinantes são essenciais para reorganização do cuidado pré-natal e redução de complicações gravídico-puerperal e fetais.

Descritores:
Gestantes; Infecções Sexualmente Transmissíveis; Cuidado Pré-Natal; Atenção Primária à Saude; Rastreamento; Prevalência

Destaques:

(1) Alta prevalência de IST não virais em gestantes. (2) As IST estão associadas às características sociodemográficas e comportamento de risco. (3) Necessário ações de educação em saúde voltadas à prevenção de IST. (4) Subsidiar a elaboração de protocolo de triagem de IST não virais na atenção pré-natal.

Objetivo: analizar los factores asociados con la ocurrencia de Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium y Trichomonas vaginalis en gestantes atendidas en la Atención Primaria de Salud.

Método: estudio transversal con 302 gestantes de 15 y 49 años. Se recolectaron muestras de secreción vaginal para detección por biología molecular de clamidia, gonorrea, mycoplasma y tricomoniasis; se aplicó un cuestionario estructurado con datos sociodemográficos, conductuales, antecedentes obstétricos y clínicos, y resultados de pruebas rápidas (Virus de la Inmunodeficiencia Humana, Sífilis, Hepatitis B y C). El análisis fue realizado con el software STATA 15.0.

Resultados: las prevalencias encontradas fueron: Chlamydia trachomatis (11,6%), Mycoplasma genitalium (9,6%), Neisseria gonorrhoeae (1,7%) y Trichomonas vaginalis (3,6%). La edad inferior a 25 años (odds ratio ajustado=2,06), la presencia de síntomas (odds ratio ajustado=1,99), la ausencia de pareja estable o una relación de hasta un año (odds ratio ajustado=2,64) aumentaron la probabilidad de tener al menos una infección.

Conclusión: este estudio describe la alta prevalencia global de infecciones de transmisión sexual curables en gestantes en la Atención Primaria de Salud. Conocer la prevalencia de estas infecciones en gestantes y sus principales determinantes es esencial para reorganizar la atención prenatal y reducir las complicaciones del embarazo, puerperio y fetales.

Descriptores:
Personas Embarazadas; Enfermedades de Transmisión Sexual; Atención Prenatal; Atención Primaria de Salud; Cribado; Prevalencia

Destacados:

(1) Alta prevalencia de ITS no virales en gestantes. (2) Las ITS están asociadas con características sociodemográficas y comportamientos de riesgo. (3) Es necesario implementar acciones de educación en salud orientadas a la prevención de ITS. (4) Subsidia la elaboración de un protocolo de tamizaje de ITS no virales en la atención prenatal.

Introduction

The World Health Organization (WHO) has estimated that there are more than 1 million new curable sexually transmitted infections (STIs) every day in people aged 15 to 49, and in 2020, it estimated 374 million new infections in this population ( ¹ ). Among women of childbearing age, the estimated global prevalence between 2009 and 2016 was 3.8% for chlamydia, 0.9% for gonorrhea and 5.3% for trichomoniasis ( ² ).

Although these STIs can cause signs and symptoms such as vaginal or urethral discharge, the presence of ulcers and pain when urinating, most cases remain symptomless, which makes both identification and appropriate treatment difficult, especially when using the syndromic approach, whose sensitivity and specificity are limited ( ³ ).

During pregnancy, physiological, hormonal and immunological changes make pregnant women more vulnerable to obstetric and fetal complications resulting from these infections, such as premature birth, early rupture of membranes, miscarriage, infertility, ectopic pregnancy, stillbirth, congenital, perinatal and puerperal infections, neonatal conjunctivitis and low birth weight ( ³ - ⁹ ).

In some developed countries, molecular tests for the screening of curable STIs in pregnant women are already used universally or targeted at at-risk populations, including women under the age of 25 ( ¹⁰ - ¹² ). In Brazil, although molecular tests for detecting Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), Mycoplasma genitalium (MG) and Trichomonas vaginalis (TV) have not yet been incorporated into the Unified Health System (SUS), the national protocol for the care of people with STIs already recommends screening for CT and NG in pregnant women under the age of 30 at the first prenatal visit ( ³ ).

Considering the limited access to etiological tests, the lack of mandatory reporting of these infections and the fragmentation of available data, prevalence studies are essential to understand the scenario of these STIs in the population ( ¹³ ). In Brazil, studies carried out with pregnant women have described a prevalence of CT of between 9%-12% ( ¹⁴ - ¹⁸ ), 0.6%-1.5% for NG ( ¹⁴ , ¹⁸ - ¹⁹ ), and 5.0%-6.7% for TV ( ¹⁴ , ¹⁸ ). The first national study to screen pregnant women for MG reported a prevalence of 7.8% in this population ( ¹⁸ ). Therefore, this study aims to analyze the factors associated with the occurrence of Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium and Trichomonas vaginalis in pregnant women followed up in Primary Health Care.

Method

Study design

A cross-sectional study originating from a pilot project by the Ministry of Health ( ¹⁸ ) (MS) to implement a molecular test for the qualitative detection of CT, NG, TV and MG in prenatal care services within the SUS, covering the five regions of the country.

Study setting

The study was carried out in the SUS prenatal services of 17 primary care centers (PCC) geographically distributed among the twelve health districts (HD) of the municipality of Salvador-BA, Brazil.

Study period

In December 2021, health professionals (physicians and nurses) attended a training session in which they were introduced to the objectives of the survey, the standardized questionnaire to be used when interviewing pregnant women, and aspects relating to the collection, packaging and transport of vaginal secretion samples to the laboratory where they were processed, as well as the treatment of STIs when they tested positive. After the training, data collection began on January 10, 2022 and ended on February 8, 2023.

Study population and selection criteria

A total of 302 pregnant women between the ages of 15 and 49, who were invited by the prenatal care provider during their prenatal consultation in Primary Health Care (PHC), took part. Pregnant women who had used any class of self-reported antibiotic in the last three months prior to collection were excluded.

Sample definition

The sample size was defined based on the estimated number of pregnant women in the municipality in 2021, which resulted from the sum of the number of live births in the previous year (2020) plus 10%, totaling 33,143 pregnant women. This calculation was made in accordance with Annex III of the Ordinance establishing the Stork Network ( ²⁰ ). Based on CT infection, which is the most frequent STI (12%) ( ¹⁷ ) expected in this population, with confidence limits of 5% and a confidence interval of 99%, a sample of 278 pregnant women was established which, plus 10% for possible losses, resulted in an n equal to 306 pregnant women. However, 313 pregnant women agreed to take part in the study. Of these, 11 were excluded from the study due to antibiotic use in the last three months (07) and incompleteness of the questionnaire (04), resulting in a sample of 302 women, maintaining an n higher than the minimum required (278). The sample calculations were carried out using the Open Epi version 3 software, available in the public domain.

Data collection

Data collection took place during a prenatal visit or at a time previously arranged for this purpose, and was carried out by a health professional (physician or nurse), who applied a structured questionnaire with sociodemographic data; obstetric data; clinical data; COVID-19 research; behavioral data; and the results of rapid tests (Human Immunodeficiency Virus/HIV, Syphilis, Hepatitis B and C). Vaginal samples were collected using Hologic’s Aptima kits to detect NG, CT, TV and MG. These are nucleic acid amplification tests (NAAT), in this case ribonucleic acid - RNA (transcription-mediated amplification), capable of detecting different pathogens in the same sample. DUO rapid tests for the simultaneous detection of circulating antibodies specific to HIV 1/2 and Treponema pallidum were also offered to all pregnant women taking part in the study who had not been tested or had been tested for more than three months.

Study variables

Sociodemographic, obstetric, clinical and behavioral data were considered predictor variables. The variables Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium, Trichomonas vaginalis were considered outcomes of interest (yes/no).

Data analysis

The absolute frequency and percentage of each of the variables of interest were explored, with the continuous variables expressed as means with their respective standard deviations. In the bivariate analysis, the percentage distribution of the independent variables in relation to each outcome variable was carried out using the Chi-Square test or Fisher’s Exact Test. All the variables with p≤0.20 were selected for multivariate logistic regression and identification of the factors associated with the outcomes of interest, estimating the Odds Ratio (OR) as a measure of association. The backward strategy was used to build the final (adjusted) model, with variables with a significance level of p≤0.05 remaining in the final model. The Hosmer-Lemershow test (p≥ 0.05) and the Receiver Operating Characteristic Curve (ROC) were used to check the fit of the model. The data was analyzed using STATA software, version 15.0.

Ethical aspects

The study was carried out in accordance with the guidelines of Resolution 466/2012, of the National Research Ethics Committee of the National Health Council (CONEP/CNS) ( ²¹ ) and submitted to the Research Ethics Committee (REC) of the State University of Bahia, with approval on December 21, 2021, CAAE 53868121.5.0000.0057. The participation of pregnant women in the study was conditional on them signing the Free and Informed Consent Form (FICF) when they were over 18 or the Free and Informed Assent Form (FASF) for those under 18. In this case, the guardians also signed the ICF. The interviews were conducted in a protected environment to preserve the participants’ privacy. The test results were only given to the participants, and positive cases were treated in accordance with the Clinical Practice Guidelines (CPG) for people with STIs.

Results

A total of 302 pregnant women (100%) took part in the study, predominantly those aged 25 or over, black (black or brown), with a high school education, even if incomplete, and a family income of up to 1.9 minimum wages. Most of the pregnant women were in a stable relationship, with two or more years of relationship, and reported having had up to five sexual partners in their lifetime and a single partner in the last 12 months. Around 4.6% (14) reported that their current partner had already been in prison. With regard to gynecological obstetric characteristics, a history of spontaneous abortion was reported by 19.9% (60) of the interviewees, and 13.9% (42) had never had a cytopathological examination of the cervix. STI symptoms were identified by almost a third of the pregnant women (99), such as vaginal discharge, dyspareunia and dysuria. As for behavioral characteristics, 16.9% (51) reported drinking alcohol, albeit occasionally or on weekends, while 3.3% (10) reported using non-injectable illicit drugs - marijuana, including concomitant use with cocaine (30.0% both drugs) (Table 1).

Table 1-
Sociodemographic, obstetric/gynecological and behavioral characteristics of pregnant women followed up in primary care center (N* = 302). Salvador, BA, Brazil, 2022-2023

Variables	n †	% ‡
Sociodemographic
Age (average)	27.7 ± 7.05
Age group
15 to 24 years	115	38.08
≥25 years	187	61.92
Color/race
White	12	3.97
Brown	139	46.03
Black	146	48.35
Indigenous	2	0.66
Yellow	3	0.99
Education
Incomplete/complete elementary school	77	25.50
Incomplete/complete high school	175	57.95
Incomplete/complete college	48	15.89
No information	2	0.66
Marital status
No stable relationship	99	32.78
Stable relationship	203	67.22
Income
Up to 1.9 minimum wages §	238	78.81
2 to 3.9 minimum wages §	55	18.21
4 to 10 minimum wages §	6	1.99
No information	3	0.99
Obstetrics/gynecological
Menarche (average)	12.6 ± 1.78
Coitarche (average)	16.3 ± 3.10
Number of sexual partnerships in life
1	55	18.21
2 to 5	183	60.60
>5	56	18.54
No information	8	2.65
Number of sexual partnerships in the year
1	273	90.40
≥ 2	29	9.60
Age at first pregnancy (average)	21.7 ± 5.43
Gestational age (average)	22.2 ± 9.38
Number of pregnancies
Primigesta	125	41.39
Multigesta	177	58.61
History of miscarriage
Yes	60	19.87
No	242	80.13
Preventive care
Yes	260	86.09
Never	42	13.91
ST Iǁ symptoms
Yes	99	32.79
Vaginal discharge	77	25.50
Dyspareunia	15	4.97
Dysuria	6	1.99
Other	1	0.33
No	203	67.21
Behavioral
Alcohol use
Yes	51	16.89
No	251	83.11
Use of non-injectable illicit drugs
Yes	10	3.31
No	292	96.69
Length of relationship with partner
No partner or ≤1 year	85	28.15
2 years or more	215	71.19
No information	2	0.66
Partner with a history of imprisonment
Yes	14	4.64
No	277	91.72
No information	11	3.64

• *N = Sample size; ^†n = Result for each variable; ^‡% = Percentage; ^§Minimum wage R$1,212.00, 2022, Brazil; ^ǁSTI = Sexually Transmitted Infection

The highest prevalences of infection were found for CT (11.6%) and MG (9.6%). Of the 302 pregnant women, five had positive vaginal secretion samples for NG (1.7%) and 11 for TV (3.6%). The prevalence of at least one of these STIs among the pregnant women interviewed was 21.5% (65) (Table 2).

A total of 13 (4.3%) pregnant women had two STIs at the same time (06 pregnant women with CT/MG, 02 with CT/NG, 02 with NG/MG and 03 with MG/TV), and only one pregnant woman tested positive for three STIs at the same time (CT/TV/MG). There were no pregnant women infected with TV/NG at the same time. No pregnant women tested positive for HIV and 24 (7.9%) tested positive for syphilis (data not shown in table).

The bivariate analysis found possible associations between each STI investigated and the independent variables, as described in Table 3. Infection with at least one STI could be associated with the following predictor variables: age between 15 and 24 years (p-0.008); two or more sexual partners in the last 12 months (p-0.000); never having had a preventive test (p-0.016); presence of STI symptoms (p-0.046); alcohol use (p-0.003); not having a partner or having been in a relationship for a year or less (p-0.001); and partner with a history of imprisonment (p-0.031). None of the STIs diagnosed showed any possible association with the variable’s race/color, family income and the number of lifetime sexual partnerships (Table 3).

Table 2-
Prevalence of infection by Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium, Trichomonas vaginalis in pregnant women followed up in primary healthcare units (N* = 302). Salvador, BA, Brazil, 2022-2023

Variables	n † = 302	% ‡
Chlamydia trachomatis
Detected	35	11.59
Not detected	267	88.41
Neisseria gonorrhoeae
Detected	5	1.66
Not detected	297	98.34
Mycoplasma genitalium
Detected	29	9.60
Not detected	273	90.40
Trichomonas vaginalis
Detected	11	3.64
Not detected	291	96.36
At least 1 STI (CT § , NG || , MG ¶ e TV**)
Detected	65	21.52
Not detected	237	78.48

• *N = Population size; ^†n = Result in each variable; ^‡% = Percentage; ^§CT = Chlamydia trachomatis; ^||NG = Neisseria gonorrhoeae; ^¶MG = Mycoplasma genitalium; **TV = Trichomonas vaginalis

Table 3-
Prevalence of infection with Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium, Trichomonas vaginalis and sociodemographic characteristics of pregnant women followed up in primary care center (N* = 302). Salvador, BA, Brazil, 2022-2023

	Chlamydia		Gonococcus		Mycoplasma		Trichomoniasis		At least 1 STI
Variables	Yes	p value §	Yes	p value §	Yes	p value §	Yes	p value §	Yes	p value §
	n † (%) ‡		n † (%) ‡		n † (%) ‡		n † (%) ‡		n † (%) ‡
Age group
15 to 24 years	26 (74.29)	0.000	3 (60.00)	0.373	13 (44.83)	0.431	4 (36.36)	1.000	34 (52.31)	0.008
≥ 25 years	9 (25.71)		2 (40.00)		16 (55.17)		7 (63.64)		31 (47.69)
Total	35 (100.0)		5 (100.00)		29 (100.0)		11 (100.0)		65 (100.0)
Color/race
Non-blacks	1 (2.86)	0.704	0 (0.00)	1.000	1 (3.45)	1.000	0 (0.00)	1.000	2 (3.08)	0.542
Blacks	34 (97.14)		5 (100.00)		28 (96.55)		11 (100.0)		63 (96.92)
Total	35 (100.0)		5 (100.00)		29 (100.0)		11 (100.0)		65 (100.0)
Education
Up to 9 years	7 (20.00)	0.414	2 (40.00)	0.606	11 (37.93)	0.112	8 (72.73)	0.001	20 (30.77)	0.287
10 years or more	28 (80.00)		3 (60.00)		18 (62.07)		3 (27.27)		45 (69.23)
Total	35 (100.0)		5 (100.00)		29 (100.0)		11 (100.0)		65 (100.0)
Marital status
No stable relationship	16 (45.71)	0.083	2 (40.00)	0.664	8 (27.59)	0.531	7 (63.64)	0.044	27 (41.54)	0.090
Stable relationship	19 (54.29)		3 (60.00)		21 (72.41)		4 (36.36)		38 (58.46)
Total	35 (100.0)		5 (100.00)		29 (100.0)		11 (100.0)		65 (100.0)
Family income
<2 minimum wages ǁ	29 (82.86)	0.611	5 (100.00)	0.587	26 (89.66)	0.225	10 (90.91)	0.472	55 (84.62)	0.257
2 or more minimum wages ǁ	6 (17.14)		0 (0.00)		3 (10.34)		1 (9.09)		10 (15.38)
Total	35 (100.0)		5 (100.00)		29 (100.0)		11 (100.0)		65 (100.0)
No. of sexual partnerships in life
1 to 5	26 (76.47)	0.479	3 (60.00)	0.243	21 (75.00)	0.399	7 (70.00)	0.409	47 (75.81)	0.245
>5	8 (23.53)		2 (40.00)		7 (25.00)		3 (30.00)		15 (24.19)
Total	34 (100.0)		5 (100.00)		28 (100.0)		10 (100.0)		62 (100.0)
No. of sexual partnerships in the year
1	27 (77.14)	0.005	3 (60.00)	0.074	22 (75.86)	0.005	9 (81.82)	0.285	51 (78.46)	0.000
2 or more	8 (22.86)		2 (40.00)		7 (24.14)		2 (18.18)		14 (21.54)
Total	35 (100.0)		5 (100.00)		29 (100.0)		11 (100.0)		65 (100.0)
No. of pregnancies
Primigravida	21 (60.00)	0.017	3 (60.00)	0.652	13 (44.83)	0.693	5 (45.45)	0.780	29 (44.62)	0.551
Multigravida	14 (40.00)		2 (40.00)		16 (55.17)		6 (54.55)		36 (55.38)
Total	35 (100.0)		5 (100.00)		29 (100.0)		11 (100.0)		65 (100.0)
History of spontaneous abortion
Yes	2 (5.71)	0.024	1 (20.00)	1.000	5 (17.24)	0.709	1 (9.09)	0.699	9 (13.85)	0.170
No	33 (94.29)		4 (80.00)		24 (82.76)		10 (90.91)		56 (86.15)
Total	35 (100.0)		5 (100.00)		29 (100.0)		11 (100.0)		65 (100.0)
Preventive testing
Yes	25 (71.43)	0.008	3 (60.00)	0.144	21 (72.41)	0.025	6 (54.55)	0.002	50 (76.92)	0.016
Never done	10 (28.57)		2 (40.00)		8 (27.59)		5 (45.45)		15 (23.08)
Total	35 (100.0)		5 (100.00)		29 (100.0)		11 (100.0)		65 (100.0)
STI symptoms
Yes	17 (48.57)	0.034	2(40.00)	0.664	9 (31.03)	0.833	4 (36.36)	0.754	28 (43.08)	0.046
No	18 (51.43)		3 (60.00)		20 (68.97)		7 (63.64)		37 (56.92)
Total	35 (100.0)		5 (100.00)		29 (100.0)		11 (100.0)		65 (100.0)
Alcohol use
Yes	8 (22.86)	0.316	0 (0.00)	0.593	11 (37.93)	0.001	3 (27.27)	0.404	19 (29.23)	0.003
No	27 (77.14)		5 (100.00)		18 (62.07)		8 (72.73)		46 (70.77)
Total	35 (100.0)		5 (100.00)		29 (100.0)		11 (100.0)		65 (100.0)
Use of non-injectable illicit drugs
Yes	2 (5.71)	0.326	2 (40.00)	0.009	2 (6.90)	0.248	1 (9.09)	0.314	4 (6.15)	0.231
No	33 (94.29)		3 (60.00)		27 (93.10)		10 (90.91)		61 (93.85)
Total	35 (100.0)		5 (100.00)		29 (100.0)		11 (100.0)		65 (100.0)
Length of relationship with partner
No partner or <= 1 year	17 (48.57)	0.005	4 (80.00)	0.024	13 (46.43)	0.026	6 (54.55)	0.049	29 (45.31)	0.001
2 years or more	18 (51.43)		1 (20.00)		15 (53.57)		5 (45.45)		35 (54.69)
Total	35 (100.0)		5 (100.00)		28 (100.0)		11 (100.0)		64 (100.0)
Partner with a history of imprisonment
Yes	5 (16.13)	0.002	1 (25.00)	0.180	1 (3.57)	1.000	0 (0.00)	1.000	6 (10.17)	0.031
No	26 (83.87)		3 (75.00)		27 (96.43)		10 (100.0)		53 (89.83)
Total	31 (100.0)		4 (100.00)		28 (100.0)		10 (100.0)		59 (100.0)

• *N = Population size; ^†n = Result in each variable; ^‡% = Percentage; ^§p = Significance level; ^ǁMinimum wage R$1,212.00, 2022, Brazil; In the variables where the frequency in the cells was less than 5, the p-value was obtained from Fisher’s Exact Test. In the other cells with values equal to or greater than 5, the Chi-Square Test was used

In the multiple logistic regression analysis, the results showed a greater chance of STI infection among pregnant women aged between 15 and 24 when compared to those aged 25 or over (adjusted Odds Ratio/ORa= 5.39; 95% Confidence Interval/CI - 2.23- 13.00); pregnant women with STI symptoms (ORa= 2.65; 95%CI - 1.15- 6.07); pregnant women without a partner or with a relationship of one year or less (ORa= 2.48; 95%CI - 1.07- 5.72); and pregnant women with a partner with a history of imprisonment (ORa= 6.81; 95%CI -1.77- 26.25) (Table 4).

With regard to NG infection, not having a partner or having been in a relationship for a year or less (ORa= 13.02; 95%CI - 1.25- 135.47) and the use of illicit non-injectable drugs (ORa= 31.83; 95%CI - 3.62- 279.79) were significantly associated. On the other hand, pregnant women who reported using alcohol were three times more likely to be infected with MG (ORa= 3.41; 95%CI -1.46- 7.93); pregnant women who had never had a preventive examination (ORa= 2.62; 95%CI - 1.04- 6.59) and who had had more than one sexual partner in the last year (ORa= 3.80; 95%CI - 1.41- 10.22) were also significantly associated (Table 4).

A significantly higher chance of TV infection was found among pregnant women with up to nine years of schooling (ORa= 7.75; 95%CI - 1.98- 30.37), the only statistically associated variable. With regard to infection with at least one STI, it was significantly associated with younger pregnant women, age between 15 and 24 years (ORa= 2.06; 95%CI - 1.16- 3.67), presence of STI symptoms (ORa= 1.99; 95%CI = 1.10- 3.60), not having a partner or having been in a relationship for less than or equal to one year (ORa= 2.64; 95%CI - 1.45- 4.78) (Table 4).

Table 4-
Multivariate analysis (final adjusted model) of factors associated with infection with Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium, Trichomonas vaginalis and having at least one STI*, among pregnant women (N^† = 302) followed up in primary healthcare units. Salvador, BA, Brazil, 2022-2023

	ORa ‡	95% CI §	P| |
Chlamydia trachomati s
Age group
15 to 24 years	5.39	2.23 - 13.00	0.000
≥ 25 years	*
STI symptoms*
Yes	2.65	1.15 - 6.07	0.021
No	*
Length of relationship
No partner or ≤1 year of relationship	2.48	1.07 - 5.72	0.033
2 years or more	*
Partner with a history of imprisonment
Yes	6.81	1.77 - 26.25	0.005
No	*
Neisseria gonorrhoea e
Length of relationship
No partner or ≤1 year of relationship	13.02	1.25 - 135.47	0.032
2 years or more	*
Use of non-injectable illicit drugs
Yes	31.83	3.62 - 279.79	0.002
No	*
Mycoplasma genitaliu m
Had a preventive exam
Yes	*		0.040
Never had a preventive exam	2.62	1.04 - 6.59
No. of sexual partners in the year
1	*		0.008
2 or more	3.80	1.41 - 10.22
Alcohol use
Yes	3.41	1.46 - 7.93	0.004
No	*
Trichomonas vaginali s
Education
Up to 9 years of study	7.75	1.98 - 30.37	0.003
10 years or more	*
At least 1 STI*
Age group
15 to 24 years	2.06	1.16 - 3.67	0.014
≥ 25 years	*
STI symptoms*
Yes	1.99	1.10 - 3.60	0.022
No	*
Length of relationship			0.001
No partner or ≤ 1 year of relationship	2.64	1.45 - 4.78
2 years or more	*

• Note: Model adjusted from backward strategy; Chlamydia trachomatis, goodness of fit test 0.0651, ROC = 0.7928; Neisseria gonorrhoeae, goodness of fit test 0.2250, ROC = 0. 8044; Mycoplasma genitalium, goodness of fit test 0.4065, ROC = 0.7172; Trichomonas vaginalis, goodness of fit test 0.7162, ROC = 0.8039; At least 1 STI*, goodness of fit test 0.8645, ROC = 0.6782
  *STI = Sexually Transmitted Infection; ^†N = Population size; ^‡ORa = Adjusted Odds Ratio; ^§IC = Confidence Interval; ^||P = Significance Level

Discussion

This study showed a high prevalence of non-viral and curable STIs (CT, NG, MG and TV) in pregnant women. Approximately 21.5% (65) of the participants had at least one of these infections. International literature reports significant variations in the prevalence of these STIs in pregnant women. In the Netherlands, one study reported a rate of 2.4% ( ²² ), while in Tanzania, 12.5% of pregnant women were infected ( ²³ ). In South Africa, a study found a prevalence of 27.0% among HIV-negative pregnant women and 40% among those living with the virus ( ²⁴ ). In the south of Brazil, a study of pregnant women treated at Santa Casa and SUS primary care center found a cumulative prevalence of STIs (including CT, NG, TV, syphilis and HIV) of 23.5% ( ¹⁴ ).

Among the STIs evaluated, CT infection was the most prevalent in this study, with a positivity rate of 11.6% (35). However, the rate of CT infection shows great global variability. Studies of pregnant women in China reported a prevalence of 6.7% ( ²⁵ ), while in Iran the rates were higher, reaching 15.5% ( ⁶ ). In South America, a study in Córdoba (Argentina) identified a rate of 6.9% ( ²⁶ ), lower than that observed in two hospitals in Lima, Peru (10.0%) ( ²⁷ ).

In the Brazilian context, a study of pregnant women in Manaus, Amazonas, found a prevalence of CT similar to that found here (11%) ( ¹⁵ ). In Coari, also in the state of Amazonas, a recent study of pregnant women followed up at the PHC revealed a prevalence of 18%, with variations depending on the type of sample used: 15% in urine and 11% in cervical-vaginal samples, analyzed by RT-PCR (real-time polymerase chain reaction) ( ¹⁶ ). These findings are consistent with those of the present study, which also used vaginal samples and molecular tests with high sensitivity, considered the gold standard by the WHO ( ²⁸ - ²⁹ ).

Still in the north of the country, a study of parturients attending a public maternity hospital in Belém (Pará) found a prevalence of 18% in urine samples from the first jet ( ³⁰ ). In the south of Brazil, in Pelotas, CT infection was identified in 12.3% of pregnant women aged up to 29 ( ¹⁷ ), while in Porto Alegre, among pregnant women treated at Santa Casa and PCC, the rate was 9.0%; both studies used vaginal samples ( ¹⁴ ).

NG infection had a prevalence of 1.7% (5) in this study, a result similar to that of investigations carried out in countries such as Japan, Kenya, Botswana, Gambia, Iran, Congo and also in Brazil, which reported rates of between 1.0% and 1.8% ( ⁶ , ¹² , ¹⁴ , ³¹ - ³⁴ ). In some regions, however, detection was lower than 1% ( ²² , ³⁵ ), including the absence of pregnant women with positive vaginal samples, according to a study carried out in Nepal and France ( ³⁶ - ³⁷ ). On the other hand, high rates were found in Papua New Guinea (11.2%) and Ethiopia (4.3%) ( ³⁸ - ³⁹ ).

Information on MG in pregnant women is still scarce, reflecting the lack of systematic screening for this agent, even in countries with consolidated prenatal CT and NG screening policies, such as the United States ( ⁴⁰ - ⁴¹ ); and the lack of extensive research investigating this STI in pregnant women. In this study, the prevalence of MG was 9.6% ( ²⁹ ), lower than that identified in two North American studies with young pregnant women (13-29 years old), in which rates of 17.0% and 18.0% were observed ( ⁴¹ - ⁴² ).

In South Africa, a study conducted in Cape Town revealed a prevalence of GDM of 12% among HIV-negative pregnant women, a percentage that doubled among those living with HIV ( ⁴³ ). Also in South Africa, rates of 13.3% were found among HIV-negative pregnant women and 22.2% among HIV-positive pregnant women ( ⁴⁴ ). In Papua New Guinea, the frequency observed was similar, with 12.5% of pregnant women testing positive for MG ( ⁴⁵ ). Discrepant results were found in Tanzania (2.1%) ( ²³ ), France (0.8%) ( ³⁷ ), and in a meta-analysis conducted in China (4.9%) ( ⁴⁶ ).

In a study conducted with women at a public university in Maringá, in the state of Paraná, Brazil, the prevalence of MG was 0.5% ( ⁴⁷ ). Recently, the first Brazilian study to screen pregnant women for GDM reported a prevalence of 7.8% ( ¹⁸ ). In a systematic review, a variation of 0.1 to 19.2% in the prevalence of MG in women was described, with most of the studies focusing on at-risk populations, with or without symptoms, attending STI clinics or living with HIV ( ⁴⁰ ). Further research is therefore needed to determine the prevalence and factors associated with this infection among pregnant women.

The TV rate obtained in the group studied was 3.6% (11), lower than that observed in studies in Africa, whose prevalence has varied between 5.0 and 7.4% ( ²³ - ²⁴ , ³³ - ³⁴ ). Most of these studies used PCR as a laboratory technique, which ensures high sensitivity and specificity in detecting infectious agents. In southern Brazil, a prevalence of TV of 5.0% in pregnant women was reported ( ¹⁴ ), a figure similar to that found in African countries.

Data compatible with that of the present study were identified in Ethiopia and Burkina Faso, with prevalences of 3.1% and 3.2%, respectively. In Ethiopia, vaginal samples were analyzed by PCR, while in Burkina Faso, urine microscopy and vaginal swabs were used ( ³⁹ , ⁴⁸ ). There is a significant frequency of TV in Papua New Guinea, where the prevalence rates were 37.6% ( ³⁸ ) and 20.1% ( ⁴⁵ ), in Haiti, with 27.7% ( ⁴⁹ ) and in sub-Saharan Africa (13.8%) ( ⁵⁰ ), showing significant regional disparities in the epidemiological profile of this infection. It should be noted that most of the research investigating this etiological agent in pregnant women is concentrated in Africa, with limited information available in the rest of the world, including Brazil.

In this study, the only variable with predictive power for TV was educational level. Pregnant women with up to nine years of schooling were seven times more likely to be infected. A similar finding was reported in a national study, in which pregnant women with incomplete primary education were twice as likely to contract STIs ( ¹⁴ ). Limited access to education can compromise understanding of the mechanisms of transmission and prevention of these infections. Less schooling is often associated with lower income, which in turn can have a negative impact on living conditions and access to health services ( ⁵¹ ). This study found that 78.8% (238) of pregnant women had an income of up to 1.9 minimum wages. However, no stratified analyses were carried out for smaller economic subgroups, nor were sources of income exclusively from social programs considered.

In terms of symptoms, 56.9% (37) of the pregnant women who tested positive for an STI were asymptomatic, and if they had been assessed using the syndromic approach alone, they would not have been diagnosed or treated properly, resulting in risks to maternal and fetal health. On the other hand, 71 women (30.0%) without infection and with symptoms suggestive of an STI, under the syndromic approach, would have been mistakenly treated. A similar scenario was described in a study in South Africa, where 70% of HIV-negative and 76% of HIV-positive pregnant women had STIs without clinical manifestations ( ²⁴ ). In southern Brazil, around 59% of infected pregnant women were also asymptomatic ( ¹⁴ ). In the Republic of Congo, it was observed that uninfected women had more symptoms than those who were actually infected, which resulted in unnecessary treatment for 110 pregnant women with negative tests, while 65% of infected women remained untreated due to the absence of clinical signs ( ³¹ ).

In the present study, despite the predominance of asymptomatic cases among the STI-positive pregnant women, there was a statistically significant association between the presence of symptoms and STI positivity, in line with the scientific literature which points to the presence of vaginal discharge, pain on urination, dyspareunia and other symptoms as increasing the likelihood of infection among pregnant women ( ³⁹ , ⁵² ). In this study, the presence of symptoms twice increased the chance of infection by CT or at least one STI.

The “juvenilization” (the shift of infections toward younger age groups) of infections reported in many studies ( ¹⁴ , ²² , ³⁵ , ⁵³ ) was also observed in this study. Being between the ages of 15 and 24 increased the chance of having an STI by twofold and the positivity of a CT infection by fivefold, affecting 22.6% of women in the 15-24 age group. In the USA, the prevalence of CT was 7.4% in puerperal women in Central Alabama and almost doubled (14.6%) when stratified by age under 25 ( ⁵³ ). In Canada, the prevalence of CT among pregnant women was low (2.0%), but rose to 9.8% among those under 25 ( ³⁵ ). In the Netherlands, pregnant women aged between 18 and 30 had a prevalence of CT of 1.8%, and 12.5% among those aged up to 20 ( ²² ). In the south of Brazil, the overall prevalence of CT was 9.0%, and 16.0% among pregnant women aged 18 to 24 ( ¹⁴ ).

The literature shows that a pregnant woman’s age under 25 is the main predictor of CT infection in various populations around the world ( ²² , ²⁷ , ³⁰ , ³⁵ , ⁵³ - ⁵⁴ ). Cervical ectopia, a common condition in sexually active young women, has also been associated with increased susceptibility to STIs ( ⁵⁵ - ⁵⁸ ).

With regard to vulnerability to STIs, social and gender characteristics lead to a low perception of risk. Having a steady partner and a stable relationship give women a sense of protection, associating STIs with promiscuous sexual behavior. In addition, the difficulty of negotiating condom use due to social and economic issues exposes women even more to STIs ( ⁵⁹ - ⁶⁰ ).

The results show that not having a partner, or having been in a relationship for up to a year, increases the chance of STI infection twice and NG 13 times. In another Brazilian study, a relationship duration of less than one year was associated with an increased chance of CT/STI infection ( ¹⁴ ). In Japan, a study showed an association between partner absence and CT infection ( ⁵⁴ ).

On the other hand, other authors have reported that having had two or more partners in the last year was the main association with CT positivity ( ¹⁶ ), and was also associated with NG infection ( ¹⁹ ). Here, having two or more partners in the last 12 months was associated with an almost four-fold increase in the chance of MG infection. This association was also reported in a review study of sexually active women ( ⁴⁰ ). This scenario of affective-sexual relationships reveals that condom use does not seem to be a consistent choice, regardless of the length of the relationship and the number of sexual partners.

In relation to infections in pregnant women with a partner who has a history of imprisonment, there is a six-fold increase in the chance of CT infection. In an investigation conducted with female partners of inmates in the three largest prison units in the state of Paraná, based on self-reported information regarding current and/or previous medical diagnosis of any STI, a prevalence of 41.2% was found ( ⁶¹ ). Although high, this percentage may represent a conservative estimate of the real magnitude of the problem, since the participants were not submitted to laboratory tests to detect STIs during data collection, and these could be asymptomatic infections, making diagnosis based on individual perception impossible.

Although having a partner in prison seems to increase women’s vulnerability to STIs, no other studies were found that describe this association with pregnant women. Therefore, future research should investigate the partner’s prison situation in more detail in relation to STI positivity in pregnant women.

It is assumed that the consumption of alcohol and/or other drugs can compromise judgment, reducing the perception of risks associated with sexual behavior, such as not using condoms, which favors exposure to STIs. In this study, the use of alcohol and non-injectable illicit substances was shown to be a predictive factor for MG and NG infection, respectively. Drinking alcohol is associated with a three-fold increase in the likelihood of MG infection, while the use of drugs such as marijuana and/or cocaine increases the chance of gonococcal infection by 31 times. In another study, despite the higher prevalence of GDM among pregnant injecting drug users (4.6%) compared to non-users (1.4%), the association was not statistically significant ( ¹⁹ ). Another study found a three-fold increase in NG positivity among pregnant women who consumed alcohol ( ⁶² ). No evidence has been found in the literature that directly explores the relationship between the use of alcohol or other drugs and MG infection ( ⁴⁰ , ⁴² - ⁴⁴ ).

Another relevant finding of this study was the association between MG infection and the absence of a Pap smear. It was found that 42 pregnant women (13.9%) had never had a Pap smear. The fact that this test is not carried out regularly, as recommended by public health guidelines, may indicate barriers to accessing health services or flaws in the organization of PHC, which often adopts a model centred on spontaneous demand. In this context, the initiative to seek the service falls to the woman herself, whether for prevention, early detection or health promotion, leaving those with less access and ties to health services more vulnerable, reducing the likelihood of receiving timely diagnosis and treatment for STIs.

This study differs in that it investigates the prevalence of curable STIs among pregnant women treated at PHC. Most international research on the pathogens CT, NG, MG and TV focuses on specific populations, such as people treated in specialized STI services, symptomatic individuals, or those living with HIV. There is a scarcity of studies that include as a target population pregnant women undergoing routine prenatal care in primary healthcare units, regardless of symptoms or history of STIs, which makes this profile an important proxy for the general population.

In this study, the use of laboratory methods that detect all four infectious agents from a single sample ensured a more effective diagnosis and appropriate treatment, and made it possible to identify infections in asymptomatic pregnant women who, in contexts where the management is exclusively syndromic, would not be diagnosed, increasing the risk of adverse gestational and neonatal outcomes, which have been widely described in the literature ( ⁴ , ⁸ , ³⁹ , ⁶³ ).

In Brazil’s current public health policy, prenatal screening in the SUS includes tests for syphilis, HIV and viral hepatitis ( ⁶⁴ ), but does not include molecular tests for the etiological agents analyzed in this study. The high frequency of curable STIs identified reinforces the need to expand the scope of tests offered to pregnant women to avoid complications in the gestational and neonatal periods. Although the data from this study showed a higher prevalence of STIs in women under 25, with symptoms, without a partner or with a shorter relationship duration, it is recommended that these tests be made universally available to all pregnant women. This approach could be more effective, both in clinical and economic terms, by preventing future complications that would generate greater costs for the health system.

In addition, there was a high level of acceptance of screening on the part of the participants. Selective strategies, based on social and behavioural markers, as well as presenting a risk of stigmatizing subgroups considered to be at higher risk, can reduce adherence to care. Therefore, universal provision during prenatal consultations appears to be the most appropriate strategy, enabling early detection of infections, timely treatment of pregnant women and their partners, and contributing to interrupting the chain of transmission.

There was no statistically significant association between STIs and variables such as history of miscarriage, marital status, family income and number of lifetime sexual partners. The study’s limitations include the lack of income stratification below 1.9 minimum wages, the failure to collect data on receipt of social benefits, the lack of information on condom use and the impossibility of longitudinal follow-up of the participants to assess adverse perinatal outcomes.

On the other hand, the study had important particularities, describing the prevalence and factors associated with infection by the four curable pathogens in pregnant women in a northeastern capital; including participants from all the health districts of the city of Salvador, increasing the representativeness of the sample; excluding pregnant women with a history of antibiotic use in the previous three months, which reduced the risk of false-negative results; and using diagnostic tests recognized for their high sensitivity. These findings help to raise the profile of curable STIs during pregnancy and can support the development of public policies aimed at screening and controlling these infections among pregnant women.

Conclusion

The findings of this study show that the high prevalence of curable non-viral STIs in pregnant women, especially among young women, is associated with sociodemographic and behavioral characteristics.

The study highlights the need for health education actions aimed at STI prevention, which would enable women to have more knowledge, greater decision-making capacity and behavioral changes, such as greater adherence to condom use. This study stands out because of the specific nature of the study sites, the population studied and the importance of PHC professionals working to improve the overall health of pregnant women.

Considering the morbidity and mortality of pregnant women and newborns as a result of these untreated infections during the gestational period, there is a need for public health policies that incorporate into Primary Care a screening program for curable STIs for all pregnant women, providing counseling, treatment, prevention, encouraging self-care, female empowerment, discussions on gender and social aspects that increase women’s vulnerability to STIs.

It is recommended that further national epidemiological studies be carried out to increase knowledge of the prevalence and risk factors for curable STIs, as well as the adverse maternal and fetal outcomes that have not been fully elucidated. It is hoped that this study will help to draw up screening protocols for non-viral STIs in prenatal care.

Acknowledgements

We would like to thank the Primary Health Care nurses for their collaboration during the data collection phase; Leilane Grazziela Nascimento Almeida for checking and typing the questionnaires; Olivete Borba dos Reis and Eneida Alves dos Santos for the logistics of transporting and packaging the samples collected at the Central Laboratory in Salvador; to Maria Luiza Bazzo and Marcos Schörner for the laboratory analysis of the samples collected and making the results available and to Angélica Espinosa Barbosa Miranda for her valuable contributions as external member of the examining commitee for the master's thesis defense.

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• Data Availability Statement
  All data generated or analysed during this study are included in this published article.
• *
  Paper extracted from master’s thesis “Infecções sexualmente transmissíveis não virais em gestantes do município de Salvador: prevalência e fatores associados”, presented to Universidade do Estado da Bahia, Salvador, BA, Brazil. Supported by Ministério da Saúde and Organização Pan-Americana da Saúde (OPAS/OMS), Grant # 22021/SCON2021-00018, Brazil.
• How to cite this article
  Souza DS, Figueiredo MAA, Travassos AGA. Non-viral Sexually Transmitted Infections in pregnant women in Primary Care: prevalence and associated factors. Rev. Latino-Am. Enfermagem. [cited]. Available from: https://doi.org/10.1590/1518-8345.7592.4695

Edited by

• Associate Editor:
  Omar Pereira de Almeida Neto

Data availability

All data generated or analysed during this study are included in this published article.

Publication Dates

• Publication in this collection
  27 Feb 2026
• Date of issue
  2026

History

• Received
  03 Dec 2024
• Accepted
  27 May 2025