Maternal obesity in prolonged pregnancy: Labor, mode of delivery, maternal and fetal outcomes

Obesity is currently not a medical indication for elective induction of labor although obese patients may not be eligible for expectant management after 41 W G. Few data on labor and complications in this population undergoing prolonged pregnancy are known. The objective of our study was to evaluate labor, mode of delivery, maternal and fetal outcomes in prolonged pregnancy in obese patients compared to normal body mass index (BMI).

It was a retrospective cohort study in patients who, after prolonged pregnancy gave birth to a single fetus, in cephalic presentation, between the first of January 2002 and December 31, 2018 in the Caen University Hospital Center. Patient's characteristics were compared within each BMI class using uni- and multivariate analysis with regression logistics models.

Overall, 9159 patients were included. Term of birth and spontaneous labor calculated rates were significantly increased in case of obesity (p < 0.001). The adjusted Odds Ratio (ORa) for induced labor in class III obesity was 1.73 [1.13-2.66]. After induction of labor, 83.0 % patients with normal BMI delivered vaginally versus 61.8 % in case of class III obesity (p < 0.001). The ORa for an emergency cesarean was 3.39 [2.04-5.63] and 1.78 [1.06-2.99] for neonatal morbidity in class III obesity.

Morbid obese patients do not belong to a low risk patient's group when pregnancy is prolonged. Elective induction in case of morbid obesity may entail less risk than allowing the pregnancy to progress after 41 W G or even 39 W G. Further randomized prospective studies are nevertheless required.