Study reveals higher risk of low birth weight in babies born to active-duty servicewomen

By Tarun Sai LomteReviewed by Lily Ramsey, LLMApr 22 2024

In a recent study published in BMJ Military Health, researchers evaluated the prevalence of preterm labor (PTL), low birth weight (LBW), preterm delivery (PTD), and stillbirth among active-duty servicewomen (ADSW).

Study: Effect of active-duty military service on neonatal birth outcomes: a systematic review. Image Credit: Bumble Dee/Shutterstock.com

Background

Females have increasingly served in the armed forces across multiple countries over the past decades. For instance, 11.5% of the United Kingdom (UK) armed forces were female by April 2023, and 16.5% of Canadian reserve and regular troops were female in 2023.

These figures are slated to grow in the future. In the United States (US), over 14,500 children were born to ADSW between 2003 and 2014. Several studies suggest a higher frequency of PTD and LBW in ADSW.

Many premature newborns are at risk of long-term disability, with neurodevelopmental disability being the most common. Further, evidence suggests that stress before and during pregnancy can have a negative impact on birth outcomes.

The military lifestyle exposes service persons to diverse stressors that may influence birth outcomes. Adverse outcomes can impact the development and health of newborns and cause occupational, emotional, and emotional challenges for parents.

About the study

In the present study, researchers reviewed the evidence on the impact of active military service on PTL, PTD, stillbirth, and LBW frequency in ADSW. They searched the Web of Science, Medline, Global Health, the Cumulative Index to Allied and Nursing Literature (CINAHL) Plus, and EMBASE databases for relevant studies.

Eligible studies included pregnant females serving in marine, land, maritime, or air military forces. High-risk pregnancies and studies on military reservists and veterans were excluded.

Titles/abstracts were screened, and full texts were reviewed. Relevant data were extracted using a structured form and Cochrane Handbook methods.

The studies included were appraised using the Joanna Briggs Institute prevalence critical appraisal tool.

The outcomes were PTD (delivery before 37 gestational weeks), LBW (birth weight < 2500 g), PTL (labor before 37 gestational weeks), and stillbirth (baby with no signs of life who died after 23 gestational weeks). The researchers performed a narrative synthesis as studies were highly heterogeneous.

Findings

Database searches identified 2342 records, and 42 were selected for full-text reviews. Overall, 21 studies were eligible for inclusion. These studies, with 650,628 participants, were published between 1979 and 2023 and were conducted in the US military. Ten studies included non-serving control populations.

Active-duty service persons’ wives constituted the most common control group. For studies without non-active-duty controls, National Vital Statistics data were used. Fifteen studies, with 273,015 births, reported PTD; eight indicated a lower prevalence of PTD in ADSW, while six indicated a higher prevalence.

Further, eight studies described LBW frequency; three reported a decreased frequency of LBW in ADSW, and five reported an increased frequency. PTL was reported in nine studies, but none defined it, preventing meaningful comparison and interpretation; PTL frequency in ADSW ranged from 2.1% to 17.7%.

Of the four studies reporting stillbirths, three were excluded. The only remaining study reported a stillbirth frequency of 0.3% in ADSW during 2003–14.

Overall, the evidence reviewed in this analysis was consistent with no increased PTD frequency in ADSW. Contrastingly, the risk of an LBW child was higher in ADSW, with 62% of studies supporting this conclusion.

A rudimentary assessment showed no relationship between the branch of service and higher PTD risk. Further, 38% and 53% of studies on LBW and PTD lacked controls, respectively; thus, a proxy control group from national data was required. As such, using the general population as a control likely skew the results toward the null hypothesis.

Conclusions

This systematic review suggested that LBW may be more prevalent in ADSW than in non-active-duty populations. Meanwhile, there was no evidence of increased stillbirths, PTL, or PTD in ADSW. All included studies were conducted in the US military, which limits generalizability.

Moreover, the high methodological heterogeneity between studies limits the generation of meaningful and robust conclusions.