Rates of recurrent preterm birth by maternal body habitus in women receiving 17α-hydroxyprogesterone caproate

Abstract

Objective: To examine the influence of maternal pre-pregnancy body mass index (BMI) on the rates of recurrent spontaneous preterm birth (SPTB) in women receiving 17α-hydroxyprogesterone caproate (17P).

Methods: Retrospective analysis of a cohort of 6253 women with a singleton gestation and prior SPTB enrolled in 17P home administration program between 16.0 and 26.9 weeks. Data were grouped by pre-pregnancy BMI (lean <18.5 kg/m², normal 18.5–24.9 kg/m², overweight 25–29.9 kg/m² and obese ≥30.0 kg/m²). Delivery outcomes were compared using χ² and Kruskal–Wallis tests with statistical significance set at p < 0.05.

Results: SPTB<28 weeks was significantly lower in normal weight women. Rates of recurrent SPTB<37 weeks were highest in the group with BMI<18.5 kg/m². Lean gravidas were younger, more likely to smoke, and less likely to be African–American than those with normal or increased BMI. In logistic regression, after controlling for race and prior preterm birth <28 weeks, the risk of SPTB<37 weeks decreased 2% for every additional 1 kg/m² increase in BMI.

Conclusions: Recurrent spontaneous preterm delivery<37 weeks in patients on 17P is more common in lean women (BMI<18.5 kg/m²), and less common in obese women (BMI ≥30 kg/m²) suggesting that the current recommended dosing of 17 P is adequate for women with higher BMI.

• 17α-hydroxyprogesterone caproate
• obesity
• prematurity

Notes

*Presented at the 29th Annual Scientific Meeting of the Society for Gynecologic Investigation, San Diego, CA, USA, March 2012.