Maternal obesity, with and without other risk factors, is associated with an increased risk for stillbirth, according to a study published online March 4 in CMAJ, the journal of the Canadian Medical Association.
Naila Ramji, M.D., from Dalhousie University in Halifax, Nova Scotia, Canada, and colleagues examined the relationship between prepregnancy maternal body mass index (BMI) and stillbirth in a retrospective cohort study using the Better Outcomes Registry and Network for singleton hospital births in Ontario between 2012 and 2018. The direct and indirect effects of BMI on stillbirth through major common-pathway complications were examined using mediator analyses.
Data were included for 681,178 births between 2012 and 2018; 1,956 were stillbirths. The researchers found that the incidence of stillbirth was increased in association with class I obesity (adjusted hazard ratio, 1.55). This association was stronger for class III obesity and strongest for class II obesity (adjusted hazard ratios, 1.80 and 2.17, respectively). Compared with those with normal BMI, those with obesity, with and without other risk factors, had a marked increase in the relative odds for stillbirth beyond 37 weeks of gestation. Minimal impact was seen for potential mediators.
According to 2014 study in The Journal of Maternal-Fetal & Neonatal Medicine, 27.1 percent of pregnant Black women were obese, and in a 2016 study in Obstetrics & Gynecology, 30 percent of maternal obesity deaths were Black women.
“Our results showed that maternal obesity was associated with an increased risk of stillbirth, particularly at term,” the authors write. “This association remained strong after partial adjustment for additional risk factors for stillbirth known to be prevalent in the obese population.”