Preclinical abortions: incidence and significance in the Norfolk in vitro fertilization program.

Clinical and prognostic significance of preclinical abortions in assisted reproduction is ill defined. Strict diagnostic criteria include a transient and synchronous elevation of serum beta-human chorionic gonadotropin (hCG), estradiol, and progesterone levels 13 days after hCG administration, ending in a bleeding episode no more than 14 days after the missed period. The preclinical abortion study group (54 patients, 178 cycles) was compared with matched control groups A (54 patients, 132 cycles) and B (54 patients, 155 cycles), representing normal term pregnancies and all outcomes, respectively. Control group C included the overall population during the study period. The abortion rate per transfer (preclinical abortion and total miscarriage rates) and total pregnancy wastage in the study group were significantly higher; the ongoing pregnancy rate was significantly lower. Preclinical abortion should be considered as a true reproductive failure with similar implications.