Table I. Differences in etiology of infertility are compared by day of transfer.

	Etiology of infertility
	Day 3	Day 5	p-value
Male factor	41.5% (447)	41.1% (897)	NS
Ovulatory disorder	17.7% (191)	28.1% (613)	< 0.001
Tubal	19.0% (205)	17.3% (378)	NS
Endometriosis	14.7% (158)	13.4% (293)	NS
Uterine	10.3% (111)	10.1% (221)	NS
Diminished reserves	30.1% (324)	12.1% (265)	< 0.001
Unexplained	5.1% (55)	3.3% (72)	< 0.05
Other	9.1% (98)	15.1% (330)	< 0.001