Effect of active-duty military service on neonatal birth outcomes: a systematic review

Introduction: Increasing numbers of women serve in the armed forces in countries worldwide. Stress experienced during pregnancy is associated with adverse birth outcomes including preterm delivery (PTD) and low birth weight (LBW). Several characteristics of military employment and lifestyle can increase stress acting on active-duty servicewomen (ADSW) and hence may increase the risk of adverse neonatal outcomes. This paper reviews the prevalence of PTD, preterm labour (PTL), LBW and stillbirth in babies born to ADSW in the armed forces.

Methods: This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol. Medline, EMBASE, Web of Science, Global Health and CINAHL Plus databases were searched from inception to July 2021 (November 2023, EMBASE) using subject heading and keyword searches for English language journal articles on babies born to ADSW in any military branch and any country. The Joanna Briggs Institute prevalence critical appraisal tool assessed risk of bias in included papers. Studies were paired with a comparator non-active-duty population to generate a prevalence ratio as the effect measure. A narrative synthesis was conducted.

Results: 21 observational studies fulfilled the eligibility criteria. They were all conducted in the US military, involved a total of 650 628 participants, and were published between 1979 and 2023. Their results indicate increased LBW in ADSW compared with non-service women. There was insufficient evidence to conclude or rule out whether ADSW have increased rates of PTD or PTL.

Conclusions: ADSW may be at increased risk of having an LBW baby. However, caution is needed if seeking to generalise the findings beyond the US context. This review highlights a growing need for female-specific research in other armed forces and, specifically, into reproductive health. Such research is necessary to inform military maternity pathways and policies in ways that safeguard mothers and their babies while enhancing military readiness.