Does 17-alpha hydroxyprogesterone caproate prevent recurrent preterm birth in obese women?
OBJECTIVE
We sought to determine if maternal weight or body mass index (BMI) modifies the effectiveness of 17-alpha hydroxyprogesterone caproate (17OHP-C).


METHODS
We performed a secondary analysis of the Maternal-Fetal Medicine Units Network Trial for the Prevention of Recurrent Preterm Delivery by 17-Alpha Hydroxyprogesterone Caproate. Binomial regression models were estimated to determine the relative risk (RR) of preterm birth (PTB) in women randomized to 17OHP-C vs placebo according to BMI category and maternal weight. Adjusted models considered inclusion of potential confounders.


RESULTS
In all, 443 women with complete data were included. 17OHP-C is effective in preventing PTB <37 weeks only in women with prepregnancy BMI <30 kg/m(2) (RR, 0.54; 95% confidence interval, 0.43-0.68). Above this BMI threshold there is a nonsignificant trend toward an increased risk of PTB (RR, 1.55; 95% confidence interval, 0.83-2.89) with 17OHP-C treatment. When analyzing by maternal weight, a similar threshold is observed at 165 lb, above which 17OHP-C is no longer effective.


CONCLUSIONS
The effectiveness of 17OHP-C is modified by maternal weight and BMI, and treatment does not appear to reduce the rate of PTB in women who are obese or have a weight >165 lb. This finding may be due to subtherapeutic serum levels in women with increased BMI or weight. Studies of adjusted-dose 17OHP-C in women who are obese or who weigh >165 lb are warranted, and current recommendations regarding the uniform use of 17OHP-C regardless of maternal BMI and weight may deserve reassessment.
Department of Obstetrics and Gynecology, Denver Health and Hospital Authority, Denver, CO; Department of Obstetrics and Gynecology, University of Colorado Denver, Denver, CO. Electronic address: kent.heyborne@dhha.org.
Kent D
KD
Heyborne
University of Colorado School of Public Health, Aurora, CO.
Amanda A
AA
Allshouse
Department of Obstetrics and Gynecology, Denver Health and Hospital Authority, Denver, CO; Department of Obstetrics and Gynecology, University of Colorado Denver, Denver, CO.
J Christopher
JC
Carey
D000077713:17 alpha-Hydroxyprogesterone Caproate; D000328:Adult; D015992:Body Mass Index; D005260:Female; D005865:Gestational Age; D006801:Humans; D006908:Hydroxyprogesterones / Q000627:therapeutic use*; D009765:Obesity / Q000150:complications*; D011247:Pregnancy; D047928:Premature Birth / Q000517:prevention & control*; D045167:Progesterone Congeners / Q000627:therapeutic use*; D012008:Recurrence
D006908:Hydroxyprogesterones; D045167:Progesterone Congeners; D000077713:17 alpha-Hydroxyprogesterone Caproate
17-alpha hydroxyprogesterone caproate; body mass index; obesity; prematurity; preterm birth; progesterone