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This article is part of the supplement: The Lives Saved Tool in 2013: new capabilities and applications

Open Access Review

The associations of birth intervals with small-for-gestational-age, preterm, and neonatal and infant mortality: a meta-analysis

Naoko Kozuki1, Anne CC Lee12, Mariangela F Silveira3, Cesar G Victora3, Linda Adair4, Jean Humphrey15, Robert Ntozini5, Robert E Black1, Joanne Katz1* and Child Health Epidemiology Reference Group Small-for-Gestational-Age-Preterm Birth Working Group1

Author affiliations

1 Department of International Health, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe St., Baltimore, MD 21205, USA

2 Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115, USA

3 Programa de Pós-graduacao em Epidemiologia, Universidade Federal de Pelotas, Rua Marechal Deodoro 1160, 3o piso, Centro, CEP 96020-220, Pelotas, RS, Brazil

4 University of North Carolina School of Public Health, 135 Dauer Drive, Chapel Hill, NC 27599, USA

5 Zvitambo, No 1 Borrowdale Road, Borrowdale, Harare, Zimbabwe

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Citation and License

BMC Public Health 2013, 13(Suppl 3):S3  doi:10.1186/1471-2458-13-S3-S3

Published: 17 September 2013

Abstract

Background

Short and long birth intervals have previously been linked to adverse neonatal outcomes. However, much of the existing literature uses cross-sectional studies, from which deriving causal inference is complex. We examine the association between short/long birth intervals and adverse neonatal outcomes by calculating and meta-analyzing associations using original data from cohort studies conducted in low-and middle-income countries (LMIC).

Methods

We identified five cohort studies. Adjusted odds ratios (aOR) were calculated for each study, with birth interval as the exposure and small-for-gestational-age (SGA) and/or preterm birth, and neonatal and infant mortality as outcomes. The associations were controlled for potential confounders and meta-analyzed.

Results

Birth interval of shorter than 18 months had statistically significant increased odds of SGA (pooled aOR: 1.51, 95% CI: 1.31-1.75), preterm (pooled aOR: 1.58, 95% CI: 1.19-2.10) and infant mortality (pooled aOR: 1.83, 95% CI: 1.19-2.81) after controlling for potential confounding factors (reference 36-<60 months). It was also significantly associated with term-SGA, preterm-appropriate-for-gestational-age, and preterm-SGA. Birth interval over 60 months had increased risk of SGA (pooled aOR: 1.22, 95% CI: 1.07-1.39) and term-SGA (pooled aOR: 1.14, 95% CI: 1.03-1.27), but was not associated with other outcomes.

Conclusions

Birth intervals shorter than 18 months are significantly associated with SGA, preterm birth and death in the first year of life. Lack of access to family planning interventions thus contributes to the burden of adverse birth outcomes and infant mortality in LMICs. Programs and policies must assess ways to provide equitable access to reproductive health interventions to mothers before or soon after delivering a child, but also address underlying socioeconomic factors that may modify and worsen the effect of short intervals.