Prospective evaluation of luteal phase length and natural fertility

Abstract

To evaluate the impact of a short luteal phase on fecundity. Prospective time-to-pregnancy cohort study. Not applicable. Women trying to conceive, ages 30-44years, without known infertility. Daily diaries, ovulation prediction testing, standardized pregnancy testing. Subsequent cycle fecundity. Included in the analysis were 1,635 cycles from 284 women. A short luteal phase (≤11days including the day of ovulation) occurred in 18% of observed cycles. Mean luteal phase length was 14days. Significantly more women with a short luteal phase were smokers. After adjustment for age, women with a short luteal phase had 0.82 times the odds of pregnancy in the subsequent cycle immediately following the short luteal phase compared with women without a short luteal phase. Women with a short luteal length in the first observed cycle had significantly lower fertility after the first 6months of pregnancy attempt, but at 12months there was no significant difference in cumulative probability of pregnancy. Although an isolated cycle with a short luteal phase may negatively affect short-term fertility, incidence of infertility at 12months was not significantly higher among these women. NCT01028365.