Obesity a risk factor for stillbirth, especially at term: Study

New Delhi, March 4

Obesity is a risk factor for stillbirth, especially as the pregnancy advances to term, according to a large study conducted in Canada.

The findings, published in the Canadian Medical Association Journal (CMAJ), suggest that an earlier delivery date may help reduce the risk of stillbirth for pregnant people with obesity.

The researchers analysed data from the Better Outcomes Registry and Network on 6,81,178 (over 6.8 lakh) singleton births, 1,956 of which were stillbirths, in Ontario, Canada between 2012 and 2018.

After adjusting for other stillbirth risk factors like diabetes and high blood pressure, they found that people with class I obesity—with body mass index (BMI) 30–34.9 kilograms per square metre (kg/m2) — had double the risk of stillbirth at 39 weeks’ gestation compared to those with normal BMI (18.5–24.9 kg/m2).

For those in obesity classes II and III (BMI 35–39.9 kg/m2 and BMI 40 kg/m2 and higher, respectively), stillbirth risk at 36 weeks was 2 to 2.5 times that of people with normal BMI, the researchers said.

This risk associated with increased BMI, a measure of body fat based on height and weight, further increased with gestational age, with a more than fourfold risk at 40 weeks, they said.

“For other medical conditions that increase the risk of stillbirth, there are guidelines that recommend delivery at 38 or 39 weeks. Interestingly, the risk thresholds for those conditions are lower than the risks we found associated with obesity,” said study lead author, Naila Ramji, an assistant professor at Dalhousie University, Canada.

“We worry that implicit biases against people with obesity may be causing the medical community to take the risks they face less seriously,” Ramji said in a statement.

The researchers also looked at whether stillbirths occurred before or during delivery and found a higher risk of stillbirths occurring before delivery in people with class I and II obesity.

They hope that these findings will improve care for this at-risk population.

“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,” Ramji added.