Association between Prenatal Care Adequacy Indexes and Low Birth Weight Outcome

A total of 368,093 live term singleton births in the state of Rio de Janeiro (Brazil) from 2015 to 2016 were investigated using data from the Brazilian Live Birth Information System (Sistema de Informações sobre Nascidos Vivos, SINASC, in Portuguese). Seven PNC adequacy indexes were evaluated: four developed by Brazilian authors (Ciari Jr. et al., Coutinho et al., Takeda, and an index developed and used by the Brazilian Ministry of Health - MS) and three by authors from other countries (Kessner et al., the Adequacy of Prenatal Care Utilization index - APNCU, and the Graduated Prenatal Care Utilization Index - GINDEX). Adjusted odds ratios were estimated for the PNC adequacy indexes by means of multivariate logistic regression models using maternal, gestational and newborn characteristics as covariates.

Results

When the PNC is classified as “inadequate”, the adjusted odds ratios to the LBWoutcome increase between 42% and 132%, depending on which adequacy index is evaluated. Younger (15 to 17 years old) and older (35 to 45 years old) mothers, those not married, of black or brown ethnicity, with low schooling (who did not finish Elementary School), primiparous, with preterm births, as well as female newborns had increasing odds for LBW. The models presented areas under the receiver operating characteristic (ROC) curve between 80.4% and 81.0%, and sensitivity and specificity that varied, respectively, between 57.7% and 58.6% and 94.3% and 94.5%.

Conclusion

Considering all PNC adequacy indexes evaluated, the APNCU had the best discriminatory power and the best ability to predict the LBW outcome.

Keywords:
maternal and newborn health; low birth weight; prenatal care; perinatal epidemiology

Index	Criterion 1	Criterion 2
Brazilian Ministry of Health¹⁸18 Ministério da Saúde. Portaria No. 569, de 1° de junho de 2000. Estabelece o Programa de Humanização no Pré-natal e Nascimento. Diário Oficial da União Sect.. 2000;1:4-6	1^st visit until 4^th month	≥ 6 visits
Ciari Jr. et al.¹⁵15 Ciari C Jr, Santos JLF, Almeida PAM. [Qualitative evaluation of prenatal care]. Rev Saude Publica. 1972;6(04):361-370. Doi: 10.1590/S0034-89101972000400005 Portuguese. https://doi.org/10.1590/S0034-8910197200...	1^st visit until 3^rd month	≥ 5 visits
Kessner et al.²¹21 Kessner DM, Singer J, Kalk CE, Schlesinger ER. Infant death: an analysis by maternal risk and health care. Washington (DC): Institute of Medicine/National Academy of Sciences; 1973	1^st visit until 3^rd month	< 22 weeks: ≥ 3 visits < 26 weeks: ≥ 4 visits < 30 weeks: ≥ 5 visits < 32 weeks: ≥ 7 visits < 36 weeks: ≥ 8 visits > 36 weeks: ≥ 9 visits
Takeda¹⁷17 Takeda S. Avaliação de unidade de atenção primária: modificação dos indicadores de saúde e qualidade da atenção [Dissertação]. Pelotas: Universidade Federal de Pelotas; 1993	1^st visit until 5^th month	≥ 6 visits
Coutinho et al.¹⁶16 Coutinho T, Teixeira MTB, Dain S, Sayd JD, Coutinho LM. [Adequacy of the prenatal care process among users of the Unified Health Care System in Juiz de Fora-MG]. Rev BrasGinecolObstet. 2003;25 (10):717-772. Doi: 10.1590/S0100-72032003001000004 https://doi.org/10.1590/S0100-7203200300...	1^st visit until 4^th month^a	≥ 6 visits
Graduated Prenatal Care Utilization Index (GINDEX)²⁰20 Alexander GR, Cornely DA. Prenatal care utilization: its measurement and relationship to pregnancy outcome. Am J Prev Med. 1987;3(05):243-253	1^st visit until 3^rd month	According to the American College of Obstetricians and Gynecologists standards^b
Adequacy of Prenatal Care Utilization index (APNCU)¹⁹19 KotelchuckM. An evaluation of the Kessner Adequacy of Prenatal Care Index and a proposedAdequacyof Prenatal CareUtilization Index.Am J PublicHealth. 1994;84(09):1414-1420.Doi: 10.2105/ajph.84.9.1414 https://doi.org/10.2105/ajph.84.9.1414... ^c	1^st visit until 4^th month	No prenatal care: 0 visits Inadequate: < 50% of expected visits Intermediate: 50% to 79% of expected visits Adequate: 80% to 109% expected visits Adequate plus: ≥ 110% of expected visits

Characteristics (n = 368.093)	Total frequency (%)	Frequency (%) of low birth weight for each category
Age of the mother (years)
15–17	7.48	9.89
18–20	13.96	7.81
21–34	64.00	6.83
35–40	12.80	8.24
41–45	1.76	10.66
Marital status
Single	63.44	7.80
Married	31.36	6.76
Widowed	0.17	7.29
Legally divorced	1.34	7.95
Stable union	3.68	6.89
Schooling
No schooling	0.12	9.79
Incomplete Elementary School	3.17	9.16
Elementary School	24.30	7.94
High School	53.09	7.34
Incomplete Higher Education	5.28	7.20
Higher Education	14.04	6.67
Occupation
Housewife	23.73	7.47
Paid activity	17.08	7.22
Unemployed or data not available	55.99	7.40
Student	3.20	9.19
Ethnicity
White	35.17	6.99
Black	10.40	8.92
Yellow	0.23	7.20
Brown	54.14	7.46
Indigenous	0.06	5.50
Parity
Primiparous	41.77	8.40
1 previous delivery	30.50	6.31
2 previous deliveries	15.37	6.69
3 previous deliveries	6.82	7.05
4 or more previous deliveries	5.54	9.06
Pregnancy
Preterm	9.64	45.23
Term	88.24	3.44
Postterm	2.12	2.20
Pilgrimage
No	73.03	7.33
Yes	26.97	7.76
Robson classification
1	17.84	4.19
2	18.52	3.75
3	16.65	3.10
4	11.00	3.25
5	23.68	2.70
6	1.38	15.76
7	1.69	14.91
8	−	−
9	0.16	14.52
10	9.07	44.04
Birth weight
Low	7.44	100.00
Normal	87.36	0.00
Macrosomia^a	5.20	0.00
Gender
Male	51.01	6.67
Female	48.99	8.25

Index	Total frequency (%)	Frequency (%) of low birth weight for each category
Ciari Jr et al.¹⁵15 Ciari C Jr, Santos JLF, Almeida PAM. [Qualitative evaluation of prenatal care]. Rev Saude Publica. 1972;6(04):361-370. Doi: 10.1590/S0034-89101972000400005 Portuguese. https://doi.org/10.1590/S0034-8910197200...
Inadequate	23.79	10.33
Adequate	76.21	6.54
Takeda¹⁷17 Takeda S. Avaliação de unidade de atenção primária: modificação dos indicadores de saúde e qualidade da atenção [Dissertação]. Pelotas: Universidade Federal de Pelotas; 1993
Inadequate	19.12	13.75
Adequate	80.88	5.95
Coutinho et al.¹⁶16 Coutinho T, Teixeira MTB, Dain S, Sayd JD, Coutinho LM. [Adequacy of the prenatal care process among users of the Unified Health Care System in Juiz de Fora-MG]. Rev BrasGinecolObstet. 2003;25 (10):717-772. Doi: 10.1590/S0100-72032003001000004 https://doi.org/10.1590/S0100-7203200300...
Inadequate	27.30	11.18
Adequate	72.70	6.04
Brazilian Ministry of Health¹⁸18 Ministério da Saúde. Portaria No. 569, de 1° de junho de 2000. Estabelece o Programa de Humanização no Pré-natal e Nascimento. Diário Oficial da União Sect.. 2000;1:4-6
Inadequate	21.37	12.79
Adequate	78.63	5.99
Kessner et al.²¹21 Kessner DM, Singer J, Kalk CE, Schlesinger ER. Infant death: an analysis by maternal risk and health care. Washington (DC): Institute of Medicine/National Academy of Sciences; 1973
Inadequate	23.45	9.15
Intermediate	34.67	7.99
Adequate	41.88	6.04
Adequacy of Prenatal Care Utilization index (APNCU)¹⁹19 KotelchuckM. An evaluation of the Kessner Adequacy of Prenatal Care Index and a proposedAdequacyof Prenatal CareUtilization Index.Am J PublicHealth. 1994;84(09):1414-1420.Doi: 10.2105/ajph.84.9.1414 https://doi.org/10.2105/ajph.84.9.1414... ^a
No prenatal care	0.04	15.94
Inadequate	20.30	10.03
Intermediate	48.12	6.31
Adequate	27.47	6.47
Adequate plus	4.08	14.40
Graduated Prenatal Care Utilization Index (GINDEX)²⁰20 Alexander GR, Cornely DA. Prenatal care utilization: its measurement and relationship to pregnancy outcome. Am J Prev Med. 1987;3(05):243-253
No prenatal care	0.04	15.94
Inadequate	6.24	10.12
Intermediate	51.73	8.25
Adequate	41.30	6.03
Intensive	0.69	6.45

Models	Ciari Jr et al.¹⁵15 Ciari C Jr, Santos JLF, Almeida PAM. [Qualitative evaluation of prenatal care]. Rev Saude Publica. 1972;6(04):361-370. Doi: 10.1590/S0034-89101972000400005 Portuguese. https://doi.org/10.1590/S0034-8910197200...	Coutinho et al.¹⁶16 Coutinho T, Teixeira MTB, Dain S, Sayd JD, Coutinho LM. [Adequacy of the prenatal care process among users of the Unified Health Care System in Juiz de Fora-MG]. Rev BrasGinecolObstet. 2003;25 (10):717-772. Doi: 10.1590/S0100-72032003001000004 https://doi.org/10.1590/S0100-7203200300...	Takeda¹⁷17 Takeda S. Avaliação de unidade de atenção primária: modificação dos indicadores de saúde e qualidade da atenção [Dissertação]. Pelotas: Universidade Federal de Pelotas; 1993	MS¹⁸18 Ministério da Saúde. Portaria No. 569, de 1° de junho de 2000. Estabelece o Programa de Humanização no Pré-natal e Nascimento. Diário Oficial da União Sect.. 2000;1:4-6	Kessner et al.²¹21 Kessner DM, Singer J, Kalk CE, Schlesinger ER. Infant death: an analysis by maternal risk and health care. Washington (DC): Institute of Medicine/National Academy of Sciences; 1973	GINDEX	APNCU^b
Models	OR [95%CI]	OR [95%CI]	OR [95%CI]	OR [95%CI]	OR [95%CI]	OR [95%CI]	OR [95%CI]
Age of the mother (years)
15–17	1.09 [1.03–1.14]**	1.06 [1.01–1.12]*	1.05 [1.00–1.11]	1.05 [1.00–1.11]*	1.09 [1.04–1.15]**	1.09 [1.04–1.15]**	1.11 [1.05–1.17]***
18–34	1.00	1.00	1.00	1.00	1.00	1.00	1.00
35–45	1.22 [1.17–1.27]***	1.24 [1.19–1.29]***	1.25 [1.20–1.30]***	1.25 [1.20–1.30]***	1.23 [1.18–1.28]***	1.23 [1.18–1.28]***	1.21 [1.17–1.26]***
Marital status
Without partner	1.08 [1.05–1.12]***	1.06 [1.02–1.09]**	1.05 [1.01–1.08]**	1.05 [1.02–1.08]**	1.08 [1.05–1.12]***	1.08 [1.05–1.12]***	1.10 [1.07–1.14]***
With partner	1.00	1.00	1.00	1.00	1.00	1.00	1.00
Schooling
Incomplete Elementary School	1.20 [1.11–1.29]***	1.18 [1.09–1.27]***	1.17 [1.08–1.26]***	1.17 [1.08–1.26]***	1.20 [1.11–1.29]***	1.20 [1.11–1.29]***	1.21 [1.12–1.30]***
Complete Elementary School	1.00	1.00	1.00	1.00	1.00	1.00	1.00
Ethnicity
White	1.00	1.00	1.00	1.00	1.00	1.00	1.00
Non-white	1.12 [1.08–1.16]***	1.10 [1.07–1.13]***	1.09 [1.06–1.13]***	1.10 [1.06–1.13]***	1.10 [1.07–1.14]***	1.10 [1.07–1.14]***	1.13 [1.09–1.16]***
Parity
Primiparous	1.00	1.00	1.00	1.00	1.00	1.00	1.00
1–3 previous deliveries	0.69 [0.67–0.71]***	0.68 [0.66–0.70]***	0.67 [0.65–0.69]***	0.67 [0.65–0.69]***	0.69 [0.67–0.71]***	0.69 [0.67–0.71]***	0.70 [0.68–0.72]***
≥ 4 previous deliveries	0.81 [0.76–0.86]***	0.78 [0.73–0.83]***	0.76 [0.71–0.81]***	0.77 [0.72–0.82]***	0.81 [0.76–0.87]***	0.81 [0.77–0.87]***	0.83 [0.78–0.88]***
Duration of the pregnancy (weeks)
≥ 37	1.00	1.00	1.00	1.00	1.00	1.00	1.00
< 37	23.46 [22.80–24.13]***	22.93 [22.28–23.59]***	22.25 [21.62–22.90]***	22.52 [21.88–23.17]***	23.72 [23.05–24.40]***	23.72 [23.06–24.41]***	23.48 [22.81–24.17]***
Gender of the newborn
Male	1.00	1.00	1.00	1.00	1.00	1.00	1.00
Female	1.41 [1.38–1.45]***	1.42 [1.38–1.46]***	1.42 [1.38–1.46]***	1.42 [1.38–1.46]***	1.42 [1.38–1.46]***	1.42 [1.38–1.46]***	1.41 [1.37–1.45]***
Adequacy of the prenatal care
No prenatal care	−	−	−	−	−	2.52 [1.42–4.32]**	1.34 [1.29–1.40]***
Inadequate	1.42 [1.37–1.46]***	1.61 [1.56–1.66]***	1.89 [1.83–1.96]***	1.79 [1.74–1.85]***	1.43 [1.38–1.48]***	1.57 [1.48–1.66]***	2.32 [1.30–3.97]***
Intermediate	−	−	−	−	1.34 [1.29–1.38]***	1.35 [1.31–1.40]***	1.10 [1.06–1.14]***
Adequate	1.00	1.00	1.00	1.00	1.00	1.00	1.00
Intensive/adequate plus^a	−	−	−	−	−	1.05 [0.88–1.26]	1.16 [1.09–1.23]***
Sensitivity (%)	58.6	57.7	57.7	57.7	58.0	58.6	58.0
Specificity (%)	94.3	94.5	94.5	94.5	94.4	94.3	94.4
Area under the curve (%)	80.5	81.0	80.7	80.7	80.4	80.5	81.0

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[1] Address for correspondence Conceição Christina Rigo Vale, Coppe/UFRJ, Programa de Engenharia Biomédica, Caixa Postal 68510, Cidade Universitária, Rio de Janeiro, Rio de Janeiro, RJ, 21941-972, Brazil (e-mail: chrisrigov@peb.ufrj.br).