Effect of short follicular phase on conception outcome

Abstract

A retrospective study was conducted to determine if having a short follicular phase despite attaining a mature follicle (18–24 mm by ultrasound and serum estradiol (E2) >200 pg/mL), is associated with reduced fecundity. The demonstration of lower pregnancy rates (PRs) prompted a prospective matched controlled study (based on age, duration of infertility, and type of follicular phase medications used). All patients were treated with progesterone (P) in the luteal phase. Early ovulation was considered as oocyte release demonstrated by day 11. Women with early follicular phase serum FSH levels >11 mIU/mL were excluded. The retrospective study (n = 21 women) revealed only 8 pregnancies in 66 cycles (12.1% per cycle) but the viable PR was only 4.6% (3/66). The PR per cycle for the 12 early ovulators in the matched controlled study was 9.0% (3/33) with a viable PR of 3.0% (1/33). The control group (later ovulators) had a 28.5% PR/cycle (14/49) and a viable rate of 18.1% (9/49). There were 13 cycles in the early ovulator group where an ovulation did occur past day 11. Four (30.7%) achieved a pregnancy and the viable PR per cycle was 23%. In the matched controlled study the mean pre-ovulatory endometrial thickness was 8 mm compared to 10.2 mm for late ovulators. These data clearly show that when a woman ovulates before day 11 she has less chance of conceiving than a woman ovulating later than day 11 even if follicular maturation is achieved and luteal phase P support is given. The fact that the PR per cycle in women from the early ovulator group, who in some cycles ovulated after day 11 was comparable to the late ovulator group suggested that the reduced fecundity was related to the short follicular phase per se and not intrinsic to conditions leading to early ovulation.