The causes of high-order multiple gestation.
Most recent reviews of multiple gestations have reported that the major cause of triplet and quadruplet pregnancy is therapy with human menopausal gonadotropin (hMG). In an attempt to decrease the number of high-order multiple gestations due to hMG, serial ovarian ultrasound evaluation was introduced in the mid-1970s. To assess the impact of changing technology on the causes of high-order multiple gestation, we reviewed the experience at our institution from 1983 to 1987. During this time period, 35,119 deliveries were performed, including 13 triplet and 2 quadruplet deliveries. Of the triplet and quadruplet pregnancies, 3 (20%) patients conceived spontaneously, 11 (73%) conceived in association with ovulation induction, and 1 (7%) conceived during an IVF cycle. Of the pregnancies associated with ovulation induction, 9 (82%) were associated with clomiphene therapy and only 2 (18%) with hMG therapy. Of the clomiphene patients, 6 (67%) conceived at a dose of 50 mg per day for five days and 5 (55%) conceived during the first cycle. At the present time, in our institution, hMG therapy is no longer the major cause of triplet and quadruplet pregnancies. It is possible that serial serum estradiol and ovarian ultrasound monitoring of hMG cycles has contributed to the low number of hMG-induced triplet and quadruplet pregnancies that we observed.