In vitro fertilization: diurnal and seasonal variation in luteinizing hormone surge onset and pregnancy rates.

The authors studied 740 consecutive in vitro fertilization (IVF) cycles over a 3-year period to compare the results of cycles in which an endogenous luteinizing hormone (LH) surge occurred with cycles in which human chorionic gonadotropin (hCG) was administered for induction of follicular maturation. Clomiphene citrate (100 to 150 mg daily on cycle days 5 to 9) and human menopausal gonadotropin (hMG; 75 to 150 IU daily from cycle day 6) were used for stimulation. Embryo transfer (ET) occurred in 164 (81.2%) of the LH surge cycles and 452 (84%; P = not significant [NS] of the hCG cycles. The first urinary rise in LH was detected in the 6 or 9 A.M. collections in 78 (47.3%) of the LH surge cycles, a greater number (P less than 0.01) than expected if LH surge onset was random. A total of 107 pregnancies was achieved, for an overall pregnancy rate of 17.4% per ET. The pregnancy rate in the hCG-stimulated cycles was 13.9% per ET (63/452) and, in spontaneous LH surge cycles, was 28.8% (44/166; P less than 0.001). The spontaneous abortion rate was 9.1% in LH surge cycles, compared with 25.4% in hCG-triggered cycles (P less than 0.001). The result was a 2.4 times increase in live births for LH surge cycles compared with cycles in which hCG was administered. In this program, occurrence of an LH surge is a favorable event, associated with higher pregnancy and live birth rates than hCG-stimulated cycles, and usually occurring in the early morning, allowing oocyte retrieval during normal working hours.