Table 5.

Percentage of Cycles That Reached Peak Fertility on a Cycle Day Within Standardized Windows Based on Cycle Length Out of All Cycles That Reached Peak Fertility According to the Fertility Monitor Used in the BioCycle Study, Buffalo, New York, 2005–2007

	Cycle 1 (n = 189)		Cycle 2 (n = 180)
	No.	%	No.	%
Fixed cycle days method (days 13–15)	77	40.7	66	36.7
Luteal-phase method (15–13 days from end of cycle)
Self-reported cycle length	73	38.6	66	36.7
Actual cycle lengtha	108	57.1	83	50.3
Midpoint method (midpoint of cycle ±1 day)
Self-reported cycle length	76	40.2	67	37.2
Actual cycle lengtha	94	49.7	73	44.2

^aCycle 2 calculations were based on the 165 women whose actual cycle length was known.