"Women Make New Eggs Each Cycle"

by Ann Douglas

MYTH:
“Women make new eggs every cycle.”

FACT:
While males set up an in-body manufacturing operation to meet ongoing demand for sperm, females employ a different egg-readiness strategy.
They pack all the eggs they’re going to need for their entire reproductive journey before they are even born.

“Females have 200,000 and 300,000 primordial egg cells at the time of birth,” says Bruce Young, MD, founder of the Division of Maternal and Fetal Medicine at NYU Medical Center; and author of Miscarriage, Medicine, and Miracles: Everything You Need to Know about Miscarriage (Bantam). “They remain in a resting state until puberty.”

That’s when things start to get exciting from a biological standpoint. During each menstrual cycle, a number of eggs begin to ripen. Your body chooses one (sometimes more than one) as the ovulatory front runner: “Your body has a way of deciding which egg is the quality egg.” 

Remember, your body is programmed to think about the long-term survival of your progeny, and that means finding the very best egg to represent your biological interests in this cycle.

Lucky for you and your reproductive odds, Mother Nature has factored a lot of excess capacity into the system. An average women releases 400 eggs through ovulation during her lifetime: less than 0.1 percent of the eggs with which she was born.

Worth noting: While there has been some rather heated debate lately about whether, in fact, a group of scientists in Shanghai may have found a way to generate mice eggs from stem cells  -- and whether that knowledge might some day be applicable to humans -- one thing isn’t open for debate: the eggs you were  born with are precious and worth protecting from every conceivable threat, including the ticking of the biological clock.

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