Tuesday, April 23, 2024

WOMAN'S HEALTH

Active military service may heighten women’s risk of having low birthweight babies


Findings highlight need for more female-specific research in armed forces, say study authors



BMJ





Active military service may heighten a woman’s risk of having a low birthweight baby, suggests a review of the available scientific evidence published online in the journal BMJ Military Health.

 

The findings highlight the need for more research specifically focused on women in the armed forces, and their reproductive health in particular, conclude the study authors.

Worldwide, increasing numbers of women are on active service in their country’s armed forces. The UK Armed Forces, for example, has set a target of 30% female representation by 2030. And more and more countries are deploying women in combat units, and in other challenging environments, such as submarines, note the study authors.

Mounting evidence suggests that stress experienced during pregnancy is associated with birth complications, such as preterm delivery and low birthweight. And a military career and lifestyle expose service personnel to a wide range of physical, mental, and environmental stressors that could potentially influence pregnancy outcomes.

The study authors therefore wanted to explore the potential impact of active military service on the risks of preterm labour and birth, low birthweight, and stillbirth.

They scoured research databases for relevant studies, and included 21 that met all the eligibility criteria in their analysis. The studies, which involved 650,628 women serving in the US military, were all published between 1979 and 2023.

Ten of the studies included a comparison group—usually the wives of active service personnel. By way of a proxy for those that didn’t include a comparator, the study authors drew on national data from the US National Vital Statistics for any given year.

Analysis of the study results indicated no heightened risk of preterm birth among pregnant active service women. But there were significant methodological differences; most studies had a moderate to high risk of bias; and several included only small sample sizes, caution the study authors.  

There was no observed association between branch of military service and increased risk of preterm birth, although again this should be interpreted cautiously as 5 studies included mixed service samples and the study design varied considerably, say the study authors.

There was no clear evidence for an increased risk of stillbirth among women on active military service, either.

But nearly two thirds (62.5%) of the studies concluded that women on active service may be at heightened risk of having a low birthweight baby, including one study with the lowest risk of bias. And 4 of the 5 studies that included a comparison group also indicated an increased risk of low birthweight.

Seven of the 8 studies reporting on low birthweight were carried out in single-service settings. Both of those from the US Air Force suggested a higher prevalence of low birthweight babies born to active duty military personnel.

But some 53% and 38% of the studies reporting on preterm birth and low birthweight, respectively, didn’t have a matched comparison group and relied on a proxy drawn from national statistical data. 

This introduces a risk of systematic error as the baseline characteristics of the two groups are inherently different, caution the study authors.

Women on active military service will also be medically screened before any tours of duty and will have fewer co existing conditions, while national data will include high risk and multiple pregnancies, they explain.

Only observational studies were included in the review, and the data collection methods and/or adjustment for influential factors varied, acknowledge the study authors. Only 8 studies reported on smoking status despite a high prevalence of smoking in the military and the fact that smoking is associated with several health issues before and during pregnancy.

The data also focused exclusively on the US military, which although unsurprising given that it is one of the largest in the world, this does limit the generalisability of the findings to armed forces personnel elsewhere, highlight the study authors.

Nevertheless, they conclude: This review highlights a need for more female-specific research in armed forces, beyond the US military setting, to inform military maternity pathways and policies in ways that safeguard mothers and their babies while enhancing military readiness.”

 

Excessive pregnancy weight gain and substantial postpartum weight retention common in military health care beneficiaries



THE OBESITY SOCIETY





ROCKVILLE, Md.— Compared to their civilian counterparts, excessive pregnancy weight gain is more frequent among military health care beneficiaries, in particular active duty personnel, and is associated with costly maternal/neonatal complications. Women in this sample with excessive pregnancy weight gain were also three times more likely to have substantial postpartum weight retention, according to a new study published in the journal Obesity, The Obesity Society’s (TOS) flagship journal.

Substantial weight retention at 12 months postpartum was also more common among military health care beneficiaries in this sample than previously documented in civilian samples. Postpartum weight retention is a key concern for the United States military because it impacts active duty women’s ability to pass their fitness tests and is also associated with long-term maternal overweight and obesity.

“These results emphasize the importance of weight management before, during and after pregnancy for military populations, given the high health care costs of weight-related health complications affecting the mother and baby as well as the importance of maintaining fitness in the active duty population,” said Rebecca Krukowski, PhD, professor, Department of Public Health Sciences, School of Medicine, University of Virginia, Charlottesville, Va. Krukowski is the corresponding author of the study.

Data for military health care beneficiaries were obtained from the Military Health System Data Repository. More than 48,000 women who had given birth in 2018 and 2019 were included. Researchers examined relationships among overweight and obesity, pregnancy weight gain, maternal and neonatal complications and substantial postpartum weight retention.

Pregnancy weight gain was determined by the amount of weight gained between a measured pre-pregnancy weight to a delivery weight. The amount of pregnancy weight gain was then compared to the national guidelines for pregnancy weight gain from the National Academy of Medicine. For body mass index, women were classified into four categories: underweight, healthy, overweight, and obesity based on the pre-pregnancy weight and height. Substantial postpartum weight retention was defined as retention of at least 10 pounds at 12-months postpartum compared with pre-conception weight. Clinical outcomes potentially related to pregnancy weight gain and body mass index were abstracted from the maternal and neonatal health care records. For maternal clinical outcomes, cases of preeclampsia, pregnancy-induced hypertension, gestational diabetes and caesarean delivery were identified. For neonatal outcomes, researchers identified infants who experienced intrauterine growth restriction, were small or large for gestational age, had low birth weight and had a neonatal intensive care unit admission.

Results showed that 75% of TRICARE beneficiaries had excessive pregnancy weight gain. Military spouses and other family members were less likely than active duty women to have excessive pregnancy weight gain. Those with excessive pregnancy weight gain and/or overweight or obesity were more likely to have maternal complications such as pregnancy-induced hypertension and cesarean delivery. The findings also showed that 42% of the military beneficiaries had substantial postpartum weight retention. Additionally, women with excessive pregnancy weight gain were three times more likely to have substantial postpartum weight retention. Researchers add that pregnancy-related weight gain above the national guidelines and substantial postpartum weight retention may make it challenging to regain the required fitness levels for active duty women and for these women (who want to serve their country) to maintain their career in the military. 

Other authors of the study include Wen You and Carol Copeland, Department of Public Health Sciences, School of Medicine, University of Virginia, Charlottesville, Va. Copeland is also with the 59th Medical Wing, Clinical Health Psychology, Joint Base San Antonio, Texas. Erin Solomon, Department of Psychology, University of Memphis, Memphis, Tenn.; Juan Lang, Department of Biostatistics, College of Public Health, University of Kentucky, Lexington, Ky.; Emily Stone, Geneva Foundation, Bethesda, Md.; Rosemary Estevez Burns, 59th Medical Wing, Clinical Health Psychology, Joint Base San Antonio, Texas; Zoran Bursac, Department of Biostatistics, Florida International University, Miami, Fla.; Marion E. Hare, Department of Preventative Medicine, University of Tennessee Health Science Center, Memphis, Tenn.; and Teresa M. Waters, Augusta University, Institute for Public and Preventative Health, Augusta, Ga.

The authors declared no conflicts of interest.

The study, titled “Overweight/Obesity, Gestational Weight Gain, Postpartum Weight Retention and Maternal/Neonatal Complications in the Military” will be published in the May 2024 issue of Obesity.

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The Obesity Society (TOS) is the leading organization of scientists and health professionals devoted to understanding and reversing the epidemic of obesity and its adverse health, economic and societal effects. Combining the perspective of researchers, clinicians, policymakers and patients, TOS promotes innovative research, education and evidence-based clinical care to improve the health and well-being of all people with obesity. For more information, visit www.obesity.org.

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