Relationship of follicle numbers and estradiol levels to multiple implantation in 3,608 intrauterine insemination cycles

Abstract

Objective: To determine the relationship of follicle numbers and estradiol (E 2) levels to multiple implantations in human menopausal gonadotropin (hMG) and clomiphene citrate (CC) cycles. Design: Fifteen-year prospective study. Setting: Private infertility clinic. Patient(s): Women who underwent 3608 cycles of husband or donor intrauterine insemination (IUI). Intervention(s): Ovulation induction (OI) with CC, hMG, or CC+hMG. Main Outcome Measure(s): Pregnancy and multiple implantations. Result(s): Triplet and higher-order implantations—but not twin implantations—were related to age, E 2 levels, and number of follicles ≥12 mm and ≥15 mm, but not number of follicles ≥18 mm, in hMG and CC+hMG cycles. For patients less than 35 years old, three or more implantations tripled when six or more follicles were ≥12 mm, in CC, hMG, and CC+hMG cycles, and when E 2 was ≥1000 pg mL in hMG and CC+hMG cycles. For patients 35 or older, pregnancy rates in hMG and CC+hMG cycles doubled when six or more follicles were ≥12 mm, or E 2 levels were >1000 pg mL, whereas 3 or more implantations were not significantly increased. Conclusions: Withholding hCG or IUI in CC, hMG, and CC+hMG cycles when six or more follicles are ≥12 mm may reduce triplet and higher-order implantations by 67% without significantly reducing pregnancy rates for patients under 35 years of age.