Low dose recombinant FSH treatment may reduce multiple gestations caused by controlled ovarian hyperstimulation and intrauterine insemination.

Objective: To evaluate the rate of multiple pregnancies in intrauterine insemination cycles stimulated with a minimal dose of recombinant follicle stimulating hormone (rec-FSH).
Design: Retrospective study.
Setting: University Medical Center.
Population: A total of 1256 patients underwent 3219 consequent intrauterine insemination cycles with minimal ovarian stimulation.
Methods: Patients received 50 or 75 IU of rec-FSH from day four to day seven. The dose was adjusted according to oestradiol (E(2)) levels in order to achieve a maximum of two follicles on the day of hCG administration.
Main Outcome Measures: Peak E(2) levels, the number of follicles >15 mm and pregnancy rates were calculated. The predictive value of E(2) levels for multiple gestations was also estimated.
Results: Of 3219 cycles, 334 resulted in pregnancies (10%). Of these, 238 (91%) were singletons, 28 (8%) twins and 1 (0.3%) was a triplet. The cumulative overall pregnancy rate was 43%. Patients over 40 years old had a significantly lower pregnancy rate per cycle and overall live birth rate (P < 0.05). Most pregnancies (83%) occurred during the first three cycles. Pregnancy rates per cycle varied from 8% for tubal factor to 14% for anovulation infertility.
Conclusions: Minimal FSH stimulation in intrauterine insemination cycles may reduce the rates of twins and high order multiple pregnancies without affecting overall pregnancy rates.