Every Woman Ovulates on Day 14 of her Menstrual Cycle -- Right?

by Ann Douglas

MYTH
"Ovulation occurs on day 14 of your menstrual cycle."

FACT
If the female reproductive cycle was this predictable,
pinpointing the timing of ovulation
would be a total no-brainer.
You'd simply pull out your calendar and
circle your date with destiny with a big, juicy, fertile "O"
(as in ovum, ovulation, orgasm – the usual mid-cycle words).

Unfortunately, Mother Nature likes to be a woman of mystery. Rather than using your current menstrual cycle to determine the timing of ovulation, she ties that all-important date to your next menstrual cycle. (She counts backwards from the first day of your next menstrual cycle and then tells you when you ovulated a half-cycle ago.)

Exactly how many days that half-cycle represents is a very individual matter. Rather than sticking with a one-size-fits-all 14-day luteal phase length, Mother Nature offers options ranging from 11 to 16 days for 95 percent of women. 

That's not to say every woman's reproductive system chugs along with clockwork precision, never missing a beat. A luteal phase can experience the occasional hiccup, losing or gaining a day. Still, that's nothing compared to the 7 day cycle-length swing that over 42 percent of women have experienced at some point (with most of those days being lost or gained on the follicular side of the cycle). And that "typical" 28.9 day cycle arrives a week earlier or later, regardless of what the calendar says.
 

Ann Douglas is the author of numerous books about pregnancy and parenting, including The Mother of All Pregnancy Books.