Risk factors for pregnancy loss apparent at conception in infertile couples.

Charts of 206 consecutive pregnancies occurring in couples seen because of infertility were analyzed in an attempt to identify factors, apparent at the time of conception, which may impose risks on pregnancy outcome. These factors were compared in 34 spontaneous abortions and 172 full-term pregnancies. Although the mean age was similar in both groups, women 35 years or older had a significantly higher incidence of spontaneous abortion than younger women. Menstrual history, gravidity, and parity and incidence of previous induced abortions were not different in the spontaneous abortion and term groups. Data collected from basal body temperature charts suggested a slightly higher risk for spontaneous abortion in women with previous anovulatory cycles. The mean follicular phase in the conception cycle was 16 days in both groups. However, a twofold increase in abortion rate was noticed in conceptions with follicular phases shorter than 12 days or longer than 16 days, in comparison with those with follicular phases of 13-15 days' duration. The mean daily temperature increment in the early luteal phase was the same in both groups. No relation between sperm count or motility and spontaneous abortion was observed. Different treatment modalities during the conception cycle had no effect on abortion rate, except for a trend toward lower spontaneous abortion incidence in women who received only prednisone.