The Ticking Clock: What’s True (and False) About Female Fertility?

Women have been bombarded by the idea that they have a better chance of space travel than conceiving over 35. Taunted by such convictions when she reached her 30s, Jean Twenge, a psychology professor at San Diego State University, scoured medical studies, quickly learning that most “facts” regarding women’s childbearing age derive from near-ancient data. The notion that a woman’s chances of conceiving are nearly nil in her late 30s, for example, derives from French birth records collected from 1670 to 1830—years before the advent of antibiotics, folic acid–fortified foods, or fertility treatments, and when few women lived past age 40. No studies Twenge found cited contemporary data, and expert organizations—including the American Society for Reproductive Medicine—cite no research for their well-promoted female fertility statistics.

“Most people assume these numbers are based on large, well-conducted studies of modern women,” Twenge wrote in a recent article published in The Guardian, “but they are not.”

Panic over the ticking biological clock intensified in 2002, upon publication of economist Sylvia Ann Hewlett’s book, Creating a Life: What Every Woman Needs to Know About Having a Baby and a Career. In it, Hewlett advises women to bear children while young or risk remaining remorsefully childless. Forty-two percent of the professional women she interviewed for the book were childless at age 40. Hewlett stated that only 14 percent of the interviewees chose not to have children, giving the impression that the remaining majority simply waited until it was too late, regrettably. She failed to mention that the 14 percent referred to how many women knew during college that they didn’t want children later on. And she failed to ask participants the most obvious question: Are you pleased with your decision? While she received criticism for these flaws, the misperceptions and panic the book triggered remained. Paired with misconstrued data and the media’s mega-microphone, it’s no wonder anxiety regarding female fertility runs rampant.

“The concern of being able to have children is significant enough that many women are willing to have a child before a committed relationship or marriage,” says Charles Shutt, MD, an obstetrician/gynecologist in Sturgeon Bay, Wisconsin. It’s the fearful motivation that’s the problem here. In fact, the concern about not being able to conceive, he says, is prevalent enough that women under age 35 account for 45 percent of doctor visits regarding reproductive assistance.

Such fear can work against women, making conception more difficult. Under duress, the body enters survival mode, a state that interferes with ovulation. A 2010 fertility and sterility study showed that women attempting impregnation with high levels of stress-related enzymes were 12 percent less likely to conceive than women with low stress markers.

Women without the desire to have kids don’t need to feel like their biological clock is broken, or may suddenly impel urges to procreate—turns out maternal inclinations guide those feelings more than science.

The most common myth regarding the biological clock is that women’s desire to have children is purely instinctual, says Amy Blackstone, PhD, an associate professor and chair of sociology at the University of Maine. “The key force behind the desire to have kids is socialization,” she says. “Children are taught from a very young age that one of the most important things they can do when they grow up is become parents.”

Girls in particular are taught that they are natural caretakers and encouraged to parent, she says. Yet no evidence indicates that women’s drive to have children is physiological, nor does a biological process exist that prompts such desire. “Children should be raised to understand that while parenthood is an important role, it isn’t the only possible important role open to them,” she adds.