Body mass index is linked to cervical length and duration of pregnancy: An observational study in low risk pregnancy.

In this prospective cohort study, one hundred participants were allocated into four groups according to their body mass indices. Vaginal ultrasound was performed at enrolment to measure cervical length. The shortest cervical measurement was recorded. Overweight and obese groups had significantly longer mean cervical length than women in the normal weight group when measured at 20-22 weeks of gestation (p < .001). Underweight women had the shortest mean cervical length. The incidence of preterm delivery was the highest in underweight women (RR; 1.5). The incidence of post-term delivery was 10% in total in overweight and obese women. Underweight women were more likely to have short cervical length and subsequent preterm delivery compared to overweight and obese women.