Back to: Introduction to Evidence Synthesis

Process: The investigators searched for published research about maternal obesity and pregnancy complications. From that evidence, they selected studies that:

1. Included data indicating a mother was obese or overweight based on her weight before she became pregnant.

2. Included a comparison group of women who were not overweight or obese before they became pregnant.

3. Presented data that could be used to calculate a mother’s level of obesity and her likelihood of cesarean delivery.

Researchers took the remaining studies and extracted the data that were related to a mother’s weight and her likelihood of cesarean delivery. They then combined the data from all of the studies to calculate an overall estimate of the likelihood an overweight, obese, or severely obese woman would get a cesarean section compared to a pregnant woman in the normal weight range.

Answer: Once researchers combined and analyzed the data, they found that the risk of getting a cesarean section was:

1.47 times higher if mother was overweight

2.05 times higher if mother was obese

2.89 times higher if mother was severely obese

From these findings, the investigators were able to generalize that “the likelihood of a cesarean delivery is about two and three times higher, respectively, among obese and severely obese compared with normal weight pregnant women.”

Based on these results and the current rate of cesarean sections in the United States, each 1% decrease in the number of birthing women who are obese would lead to 16,000 fewer cesarean sections a year. That’s useful knowledge for any policy makers or clinicians hoping to decrease the overall rate of cesarean sections.