Trial of Progesterone in Twins and Triplets to Prevent Preterm Birth (STTARS)

Women with multifetal gestation face numerous risks in excess of those faced by women with singleton gestation. Preterm birth is by far the most common and the most significant of these problems, yet no intervention or approach has served to reduce this risk. The prevalence of preterm birth has risen dramatically in recent years, in large part due to Assisted Reproductive Technologies. Consequently, the problem of preterm birth has assumed an even greater role in contributing to perinatal morbidity and mortality. The recently completed trial by the NICHD sponsored Maternal Fetal Medicine Units (MFMU) Network has, for the first time, demonstrated a treatment (i.e. progesterone therapy) that substantially reduces the rate of preterm birth in women at high risk for preterm delivery because of a prior spontaneous preterm birth . Preterm birth was reduced by 35% among progesterone-treated women when compared with women receiving placebo. Given this dramatic benefit and the extremely high risk of preterm birth in women with multifetal gestation, a trial to evaluate the benefit of progesterone in women with multifetal pregnancy is appropriate and timely. This protocol outlines a randomized, double-masked clinical trial comparing weekly treatment by injection of 17 alpha-hydroxyprogesterone caproate (17P) with placebo in women with twin or triplet gestation. In an ancillary study, the pharmacokinetics and pharmacodynamics of 17P in multifetal gestation will be studied. This trial aims to enroll six hundred women with twin gestation and one hundred twenty women with triplet gestation between 16 weeks 0 days to 20 weeks 6 days. At the initial screening evaluation, and after signing the informed consent form, the patient will receive an injection of the placebo (1 ml inert castor oil). She will be asked to return after three days for randomization. During this compliance test period, an ultrasound exam will be scheduled, if not previously done. When the patient returns and if she still meets the inclusion criteria, she will be randomized to one of two treatments: * 17 a-hydroxyprogesterone caproate: weekly 1 ml injections containing 250 mg of 17P * Placebo: weekly injections of 1 ml placebo inert castor oil Treatment will be given through 34 weeks 6 days gestation or delivery. At the time of consent to the main study, the patient will also be asked to participate in an ancillary study. If she agrees, she will have 30 cc of blood drawn at 24-28 weeks and at 32-35 weeks gestation. A pelvic exam will be done at the same two times to collect vaginal specimens and to determine Bishop score.