Obesity Increases Stillbirth Risk, Especially at Term

Obesity stands as a perilous factor for stillbirth risk, with its threat escalating as pregnancy progresses toward term, as revealed by an extensive study unveiled in the esteemed CMAJ (Canadian Medical Association Journal).

The overall likelihood of stillbirth during pregnancy hovers at approximately 0.4% in Canada. “Our discoveries intimate that advancing the delivery date might mitigate the risk of stillbirth among expectant individuals grappling with obesity,” expressed lead author Dr. Naila Ramji, a specialist in high-risk pregnancies based in Fredericton, New Brunswick, and an adjunct professor at Dalhousie University. She was joined by co-authors from The Ottawa Hospital and senior author Dr. Laura Gaudet, a high-risk pregnancy specialist and associate professor at Queen’s University.

While the correlation between obesity and stillbirth remains widely acknowledged, scant attention has been paid to investigating the nexus between obesity and stillbirth risk across different stages of gestation or the ramifications of severe obesity grades.

To bridge this void, the investigators scrutinized data from the Better Outcomes Registry and Network encompassing 681,178 singleton births, including 1,956 stillbirths, transpiring in Ontario from 2012 to 2018. After adjusting for other stillbirth risk factors like diabetes and hypertension, the researchers unearthed that individuals with class I obesity (BMI 30–34.9 kg/m²) confronted double the risk of stillbirth at 39 weeks’ gestation compared to those with a normal BMI (18.5–24.9 kg/m²). For those categorized under obesity classes II and III (BMI 35–39.9 kg/m² and BMI 40 kg/m² and above, respectively), the risk of stillbirth at 36 weeks was 2 to 2.5 times higher than that of individuals with a normal BMI. This peril augmented with advancing gestational age, escalating to more than a fourfold risk at 40 weeks.

“Unlike other medical conditions elevating the risk of stillbirth, which warrant delivery at 38 or 39 weeks, it’s intriguing that the risk thresholds for those ailments are comparatively lower than the risks tethered to obesity. We are concerned that latent prejudices against individuals grappling with obesity may be undermining the gravity of risks they confront,” voiced Dr. Ramji.

Furthermore, the authors explored whether stillbirths transpired before or during delivery, unearthing a heightened risk of antepartum stillbirths among individuals with class I and II obesity.

They anticipate that these revelations will enhance care for this vulnerable demographic.

“Pregnant people with obesity, especially those with additional risk factors may benefit from timely referral and greater surveillance closer to term, and the presence of additional risk factors may warrant earlier delivery.” – Dr. Naila Ramji, Lead Author

In a related editorial, CMAJ editor Dr. Naomi Cahill urges that health care providers take a nuanced approach in prenatal counselling of patients with obesity.

“Focusing on weight during communications of risk may reinforce weight bias, weight stigma, and discrimination for pregnant people,” writes Dr. Cahill, a registered dietitian. “Negative weight-related attitudes, beliefs, assumptions, and judgments prevalent in society, and harmful social stereotypes that are held about people living with obesity, are associated with adverse physical and mental health consequences.” She ends by saying that pregnant people living with obesity “….should receive respectful prenatal care, free from stigma, that realizes the goals of both health care providers and patients to ensure positive maternal and fetal outcomes.”

For more information: The impact of isolated obesity compared with obesity and other risk factors on risk of stillbirth: a retrospective cohort study, Canadian Medical Association Journal, https://www.cmaj.ca/lookup/doi/10.1503/cmaj.221450