Among women with a cerclage, pre-pregnancy BMI was not a significant predictor of SPTB <35 weeks.
There was a non-significant trend toward increased rates of SPTB at all gestational age cutoffs.
Morbidly obese women consistently had worse outcomes than obese and normal/overweight women.
Compared to normal/overweight, GA at delivery decreases by 1 week for obese and 2 weeks for morbidly obese women.
Suhag, MD, A.; Seligman, MD, N. S.; and Berghella, MD, V., "Body Mass Index and Cerclage Success" (2010). Department of Obstetrics and Gynecology Faculty Papers. Paper 14.