Prevalence and temporal trend of prematurity in Brazil before and during the COVID-19 pandemic: a historical time series analysis, 2011-2021

Alberton, Marcos; Rosa, Vanessa Martins; Iser, Betine Pinto Moehlecke

doi:10.1590/S2237-96222023000200005

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Brasil

Epidemiologia e Serviços de Saúde

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ORIGINAL ARTICLE • Epidemiol. Serv. Saúde 32 (2) • 2023 • https://doi.org/10.1590/S2237-96222023000200005 copy

Prevalence and temporal trend of prematurity in Brazil before and during the COVID-19 pandemic: a historical time series analysis, 2011-2021

Prevalencia y tendencia temporal de la prematuridad en Brasil antes y durante la pandemia de COVID-19: análisis de la serie histórica de 2011 a 2021

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Objective:

to measure the prevalence of prematurity according to the Brazilian macro-regions and maternal characteristics over the past 11 years; to compare the proportions during the COVID-19 pandemic (2020-2021) with those of the historical series (2011-2019).

Methods:

this was an ecological study, with data from the Live Birth Information System; the prevalence was calculated according to year, macro-region and maternal characteristics; time series analysis was performed using Prais-Winsten regression model.

Results:

the prevalence of preterm birth in 2011-2021 was 11.1%, stable; the average in the pandemic period 11.3% (95%CI 11.2;11.4%) was similar to that of the base period 11.0% (95%CI 10.6;11.5%); the North region (11.6%) showed the highest proportion between 2011 and 2021; twin pregnancy (56.3%) and pregnant women who had 4-6 prenatal care visits (16.7%) showed an increasing trend (p-value < 0.001); the highest prevalence was observed for extremes of maternal age, pregnant women of Black race/skin color, indigenous women and those with lower level of education.

Conclusion:

preterm birth rates were highest for socially vulnerable pregnant women, twin pregnancies and in the North; stable prevalence, with no difference between periods.

Keywords:
COVID-19; Preterm Birth; Premature Baby; Time Series Studies; Brazil

Brazil and macro-regions	Average prevalence (%)	Point prevalence (%)			Trend from 2011 to 2021
Brazil and macro-regions	2011-2021	95%CI^a	2011	2021	β Coeff^b	95%CI^a	p-value	Interpretation
Brazil	11.1	10.7;11.4	9.8	11.3	0.46	-0.85;1.77	0.448	Stable
North	11.6	11.2;12.1	9.9	11.8	0.78	0.96;2.53	0.338	Stable
Northeast	11.0	10.8;11.2	10.5	11.2	0.16	-0.63;1.05	0.656	Stable
Southeast	10.9	10.5;11.3	9.3	11.3	0.72	-0.48;1.93	0.209	Stable
South	11.1	10.6;11.5	9.4	11.3	0.47	-1.34;2.28	0.570	Stable
Midwest	10.8	10.6;11.1	10.0	11.3	0.69	-0.22;1.58	0.114	Stable

Maternal and gestational characteristics	Average prevalence (%)	Point prevalence (%)			Trend from 2011 to 2021
Maternal and gestational characteristics	2011-2021	95%CI^a	2011	2021	β Coeff^b	95%CI^a	p-value	Interpretation
Mother’s age (in full years)
10-19	12.6	12.2;13.0	11.2	12.4	-0.04	-1.76;1.67	0.954	Stable
20-29	10.0	9.7;10.3	8.9	10.1	0.23	-1.01;1.48	0.677	Stable
30-39	11.6	11.2;12.0	10.3	12.2	0.86	-0.35;2.07	0.141	Stable
≥ 40	14.9	14.5;15.4	13.2	15.8	1.56	0.13;3.00	0.095	Stable
Mother’s schooling (in complete years of study)
1-3	12.9	12.4;13.4	10.9	13.8	1.47	-0.11;3.05	0.065	Stable
4-7	12.2	11.8;12.6	10.4	12.7	0.99	-0.67;2.66	0.211	Stable
8-11	10.7	10.4;11.1	9.4	11.1	0.64	-0.61;1.89	0.277	Stable
≥ 12	10.8	10.5;11.2	9.6	11.1	0.48	-0.56;1.53	0.324	Stable
Mother’s race/skin color
White	11.0	10.6;11.4	9.3	11.3	0.71	-0.81;2.23	0.316	Stable
Black	11.8	11.6;12.1	11.7	11.7	-0.62	-1.43;0.18	0.110	Stable
Mixed race	11.0	10.7;11.3	10.0	11.1	0.27	-0.97;1.50	0.631	Stable
Asian	11.2	10.9;11.6	10.0	11.6	0.71	-0.75;2.37	0.300	Stable
Indigenous	14.4	13.7; 15.0	14.3	14.2	-0.59	-4.07;2.88	0.706	Stable
Type of pregnancy
Single	10.1	9.8;10.4	9.0	10.2	0.17	-1.16;1.51	0.078	Stable
Twin	56.3	54.1;58.6	50.5	61.2	9.81	8.82;10.81	< 0.001	Increase
Number of prenatal care visits
1-3	21.8	21.3;22.3	196.3	21.9	1.15	-1.02;3.33	0.260	Stable
4-6	16.7	15.9;17.6	136.2	18.5	3.54	2.13;4.97	< 0.001	Increase
≥ 7	8.0	7.7;8.4	6.7	8.5	0.82	-0.36-2.01	0.149	Stable
Type of delivery
Vaginal	11.0	10.6;11.4	10.0	10.6	-0.52	-2.20;1.15	0.498	Stable
Cesarean section	11.1	10.7;11.5	9.7	11.9	1.23	0.13;2.34	0.093	Stable

Variables	Average prevalence (%) Pre-pandemic period: 2011-2019	95%CI^a	Average prevalence (%) Pandemic period: 2020-2021	95%CI^a
Brazil	11.0	10.6;11.5	11.3	11.2;11.4
North	11.6	11.0;12.1	11.9	11.5;12.2
Northeast	11.0	10.8;11.2	11.2	10.6;11.8
Southeast	10.8	10.3;11.3	11.3	11.0;11.6
South	11.0	10.4;11.6	11.3	10.7;11.9
Midwest	10.8	10.5;11.0	11.2	10.9;11.6
Mother’s age (in full years)
10-19	12.6	12.1;13.1	12.5	11.6;13.3
20-29	10.0	9.5;10.4	10.1	10.0;10.2
30-39	11.5	11.1;11.9	12.1	11.5;12.8
≥ 40	14.8	14.3;15.3	15.7	14.6;16.8
Mother’s schooling (in complete years of study)
1-3	12.7	12.2;13.3	13.6	10.9;16.3
4-7	12.1	11.6;12.6	12.6	12.1;13.1
8-11	10.7	10.2;11.1	11.1	11.0;11.2
≥ 12	10.8	10.4;11.2	11.1	10.9;11.3
Mother’s race/skin color
White	10.9	10.4;11.4	11.3	10.8;11.8
Black	11.8	11.5;12.2	11.7	11.6;11.8
Mixed race	11.0	10.6;11.3	11.2	10.9;11.4
Asian	11.1	10.7;11.6	11.7	10.9;12.5
Indigenous	14.4	13.6;15.3	14.1	12.7;15.4
Type of pregnancy
Single	10.1	9.6;10.5	10.2	10.1;10.3
Twin	55.4	53.2;57.5	60.8	54.9;66.7
Number of prenatal care visits
1-3	21.9	21.2;22.5	21.6	17.9;25.3
4-6	16.4	15.5;17.4	18.0	12.7;23.4
≥ 7	7.9	7.5;8.3	8.5	8.0;8.9
Type of delivery
Vaginal	11.1	10.5;11.6	10.7	9.4;12.0
Cesarean section	11.0	10.6;11.4	11.8	10.7;12.9

Variables	2011	2012	2013	2014	2015	2016	2017	2018	2019	2020	2021
Brazil	9.8	11.9	11.5	11.2	10.8	11.1	10.9	11.0	11.1	11.3	11.3
North	9.9	12.5	12.1	11.8	11.4	11.5	11.4	11.6	12.1	11.9	11.8
Northeast	10.5	11.3	11.3	11.1	10.9	11.3	10.9	10.8	10.8	11.3	11.2
Southeast	9.4	12.2	11.7	11.2	10.8	11.0	10.9	11.0	11.0	11.2	11.3
South	9.3	11.8	11.0	10.9	10.6	11.0	10.8	11.0	11.1	11.2	11.3
Midwest	10.0	11.3	11.0	10.8	10.7	10.7	10.5	10.9	11.0	11.2	11.3
Mother’s age (in full years)
10-19	11.2	13.6	13.3	12.9	12.5	12.8	12.5	12.4	12.4	12.5	12.4
20-29	8.9	10.8	10.4	10.1	9.8	10.1	9.8	9.9	9.9	10.1	10.1
30-39	10.3	12.3	11.8	11.5	11.3	11.6	11.5	11.6	11.7	12.1	12.2
≥ 40	13.2	15.4	15.1	14.7	14.5	14.7	14.9	15.1	15.4	15.6	15.8
Mother’s schooling (in complete years of study)
1-3	10.9	13.3	13.0	12.9	12.6	13.1	12.9	13.1	12.7	13.4	13.8
4-7	10.4	12.9	12.6	12.3	12.0	12.3	12.1	12.2	12.2	12.6	12.7
8-11	9.4	11.4	11.1	10.8	10.4	10.8	10.7	10.7	10.8	11.1	11.1
≥ 12	9.6	11.6	11.0	10.9	10.7	10.9	10.6	10.8	11.0	11.1	11.1
Mother’s race/skin color
White	9.3	11.9	11.4	11.0	10.7	11.0	10.9	11.0	11.1	11.3	11.3
Black	11.7	12.7	12.3	12.0	11.5	11.9	11.5	11.5	11.5	11.7	11.7
Mixed race	10.0	11.8	11.5	11.1	10.8	11.0	10.8	10.9	11.0	11.2	11.1
Asian	10.0	11.8	11.7	11.4	11.0	11.4	10.5	11.2	11.4	11.7	11.6
Indigenous	14.3	15.9	16.1	15.2	14.4	14.0	13.5	12.9	13.6	14.0	14.2
Type of delivery
Single	9.0	11.0	10.6	10.3	9.9	10.2	9.9	9.9	10.0	10.2	10.2
Twin	50.5	53.8	53.2	54.6	54.7	56.3	57.1	58.6	59.5	60.3	61.2
Number of prenatal care visits
1-3	19.6	22.4	21.9	21.8	21.7	22.2	22.3	22.3	22.3	21.3	21.9
4-6	13.6	16.4	16.1	16.1	16.2	16.9	17.1	17.5	18.1	17.6	18.5
≥ 7	6.7	8.6	8.2	8.0	7.7	8.0	7.8	8.0	8.2	8.5	8.5
Type
Vaginal	9.9	12.2	11.8	11.5	10.9	11.1	10.8	10.7	10.6	10.8	10.6
Cesarean section	9.7	11.6	11.2	11.0	10.8	11.2	11.1	11.2	11.4	11.7	11.9

Secretaria de Vigilância em Saúde e Ambiente - Ministério da Saúde do Brasil SRTVN Quadra 701, Via W5 Norte, Lote D, Edifício P0700, CEP: 70719-040, +55 61 3315-3464, Fax: +55 61 3315-3464 - Brasília - DF - Brazil
E-mail: ress.svs@gmail.com

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[1] Correspondence:
Betine Pinto Moehlecke Iser.
E-mail:
betinee@gmail.com