WASHINGTON, June 28, 2013 – A widely read article by Jean Twenge in the latest issue of The Atlantic magazine questions the science and facts behind the popular belief that women can and should not have children over the age of 35. As it turns out, many of the studies this advice is based on are outdated and unreliable.
So, is there hope for the over 35 to have one or—dare we dream?— more children?
In the “Luck be an Old Lady” episode of Sex and the City, the women travel to Atlantic City to celebrate Charlotte’s 36th birthday. Toward the end, Carrie drifts toward a roulette table and wonders what number to place her bet on (1-36).
When se can’t decide, she asks, “What happens after 36?”
“I don’t know,” says the dealer. “I guess you fall off the table.”
Carrie places her bet on 36—and loses.
When it comes to having children, many women wonder the same thing: in terms of pregnancy, what happens after 36? Do we literally fall off the table?
Popular and scientific wisdom for years have agreed that, in general, women who haven’t had children before 35 are not likely to have them at all, or at least have a very difficult time doing so.
“About one-third of couples in which the woman is older than 35 years have fertility problems,” according Centers for Disease Control and Prevention’s (CDC) webpage on fertility. “Aging not only decreases a woman’s chances of having a baby but also increases her chances of miscarriage and of having a child with a genetic abnormality.”
In her now popular article, Twenge debunks many of the myths associated with the possibilities, outcomes, and rates of conception after the dreaded three-five.
However, not all women are cheering.
The problem with the statistic
There is a highly publicized statistic that one in three women between the ages of 35 and 39 will be unsuccessful in getting pregnant after one year of trying; in other words, less than 67% of these women will get pregnant.
However, Twenge points out that this information is based on a 2004 article by Henri Leridon in the journal Human Reproduction using data from birth records dating from 1670 to 1830 in France.
Moreover, Twenge highlights three recent studies that place success rates in women 35 to 39 between 78 and 82%, just four to six percentage points below the success rates of 24 to 34-year-olds.
In other words, women have been making important life decisions, putting off career and other opportunities, based on information about women who never saw a light bulb, antibiotics, or even had a steady supply of food.
A difficult measurement
Fertility decrease due to age may be overrepresented by the methods used to measure it, according to Twenge. For one thing, estimates of fertility and age based on In Vitro fertilization (IVF) success rates may be misleading because only about one percent of babies born in the U.S. every year are a result of IVF, 80% of IVF patients are 40 or younger, and most women who seek IVF have other issues including blocked fallopian tubes or male infertility (both independent of the mother’s age).
Besides several other limitations to measuring fertility, according to Twenge, because highly fertile women are more likely to have accidental pregnancies when they are younger or get pregnant as soon as they start trying (regardless of age), women over 35 who are trying to get pregnant for the first time may be less fertile than the average over-35 woman and therefore skew the data.
Miscarriage and birth defects
Beyond the ability to get pregnant, older women are often told that their risk of miscarrying and giving birth to a child with birth defects increases dramatically over age 35.
In her article, Twenge takes an optimistic view of the statistics, “even for older women, the likelihood of a pregnancy’s continuing is nearly three times that of having a known miscarriage,” she writes.
Twenge also takes an optimistic view of the risk of chromosomal abnormalities increasing with maternal age. The article quotes early fetus testing showing that only one percent of fetuses in pregnant 35-year-old women show abnormalities and three percent of fetuses in 40-year-old pregnant women.
In the end, Dr. Twenge suggests that women plan to have their last child by age 40, in effect giving some women a four-year reprieve. But not everyone sees it that way.
Feeling relieved? Not so fast
Despite all the buzz the article received, it has also attracted criticism.
“I want every doctor, scientist and researcher to read these statistics and stop referring to any woman over 35 as of ‘advanced maternal age,’” writes Amy Klein in The New York Times. “On the other hand, because of my history, I am afraid Dr. Twenge is giving women the rope with which to hang themselves.”
In Klein’s case, the problem was not getting pregnant; it was staying pregnant. While she had no trouble conceiving at 41, Klein had two subsequent miscarriages.
Klein says that by raising the age after which women should not have children from 35 to 40, women may think that they have more time than they really do to discover and deal with problems in conception or carrying the pregnancy to term.
Klein gives a face to the statistics quoted by Twenge from the National Vital Statistics Reports (NVSR). According to the NVSR, miscarriages occur in 15% of women 20 to 34, 27% in women 35 to 39, and 26% in women 40 to 44. So while it is true that the likelihood of a successful pregnancy is nearly three times that of a miscarriage in older women, it is also true that the probability of having a miscarriage nearly doubles after 35.
What the Twenge article fails to take into consideration is that addressing this and other problems will require time that some women may not have if they delay pregnancy from 35 to 40.
“I’m not sure what to do with this information,” writes Johnna Kaplan at the Jewish Daily Forward. “I imagine that mid- to late-30s women who are currently in a position to have children but who had put it off due to financial or logistic concerns might be thrilled to find that their choices are not as limited as they feared. But for single women (who do not want to be single mothers) the happiness of ‘My eggs are still good!’ segues quickly into ‘Four more years to find a man!’ The inward pressure and outward judgment were already there, but introducing that second chance – which is really a last chance - does nothing to quell them and perhaps even makes them worse.”