To determine if a short follicular phase despite attaining a mature follicle is associated with a lower pregnancy rate. Furthermore the study would determine if delaying the maturation of the follicle by the use of ethinyl estradiol could improve the pregnancy rate.The clinical and viable pregnancy rates of 32 infertile patients were matched to 32 similar controls who ovulated at or past day 11. After 2-3 cycles of demonstrating ovulation before day 11 some patients were treated with ethinyl E2, 20 mcg daily, from day 2 of the cycle until ovulation.Clinical and viable pregnancy rates for the normal ovulators (84.4%, 59.3%) were significantly higher than the rates for early ovulators (21.8%, 9.3%). However, the pregnancy rates were 83.3% and 66.7% for the subset of early ovulators who were made to ovulate later by ethinyl E2.The short follicular phase per se reduces fecundity.