When Virginia Woolf was told that female brains were smaller than male brains and therefore less capable, she retorted that science was infected with the patriarchal virus. For centuries, this virus not only rendered female brains unworthy of study, it also influenced medical and popular attitudes about pregnancy and motherhood.
Not that long ago, delaying motherhood to pursue work or an education was viewed with skepticism, if not outright hostility. Concerned grandmothers were likely to take an aspiring careerist aside and stage-whisper that, if she put off babies for her work -- or God forbid, an advanced degree -- her ovaries might just shrivel up. In the early part of this century, medics intimated that delaying motherhood could lead to all kinds of nervous diseases, including false or hysteric pregnancies known as "puff" babies. Teddy Roosevelt singled out mothers of big families as the ultimate role models for young women. In a 1903 presidential address, he claimed that any woman who balked at having children was a "criminal against the race" and an "object of contemptuous abhorrence."
Women can heave a collective sigh of relief that sociocultural mores about late motherhood have changed, thanks largely to the women's movement. Still, some gray-haired mothers who find themselves panting after toddlers may still wonder what shape they'll be in when their kids hit the teen years. After all, don't young mothers sail unscathed through pregnancy and the postpartum period with rubber band waists, while their older counterparts face a higher incidence of varicose veins, high blood pressure, gestational diabetes and other complications? Is early motherhood better for your body? Not necessarily, according to a series of recent studies on aging and reproduction. They suggest that it behooves women to do what growing numbers of them are doing anyway: Have children late and infrequently.
European researchers, drawing on 12 centuries of genealogical records of the British aristocracy, have shown a clear tradeoff between early childbearing and longevity. In an article published last December in Nature, two gerontologists at the University of Manchester found that women who delay having children until their 30s and 40s, and then have only one or two, are more likely to live into their 80s, 90s and beyond. Female longevity, they say, is linked to the number of children a woman has and her age at the birth of her first child. This study comes in the wake of another carried out in the Boston area by a team of Harvard researchers led by Thomas T. Perls. It showed that centenarians are four times more likely than the general population to have had their first child in their 40s.
Consider the late Madame Jeanne Calment of Arles, France. Despite eating two pounds of chocolate a week and smoking until the age of 117 (when she reportedly stopped because she could no longer light up unaided), she managed to make it to a record-breaking 122 years. University of Georgia gerontologist Daniel Promislow speculates that her long life may well have been due, at least in part, to her having only one child.
Reading these studies, I also found myself thinking of my 80-year-old mother, who is still out on the tennis court lobbing backhands past opponents half her age. In the past, I had attributed her seemingly eternal youth to her hardy Swiss genes -- though her parents died young and looked their age. But maybe the answer lies more in my belated entrance into her life: She had me at the age of 45.
It turns out that the experience of my mother and the British noblewomen confirm the findings of studies of Drosophila fruit flies, those pesky nuisances of
college biology labs. Studies have found that flies selectively bred for longevity have fewer young, and flies selected for late fertility live longer and are more resistant to stress and disease. These studies point to a genetic link
between bearing offspring early and dying young. Older mothers should not get too smug, however: Both male and female flies prevented from mating at all live the longest. And, like the flies, childless women on average do live longer, despite a higher rate of breast and endometrial cancer. Nearly half of the British aristocrats who lived into their 80s and 90s had no children, while less than a third of women who lived only into their 50s and 60s were childless. Since they were all married, we can happily assume that, unlike the female flies, it was not celibacy that accounted for their longevity.
To any mother who has struggled through sleepless nights or
battled a steady onslaught of baby-born viruses or nursed a sick child, the link between number of children and parental life span seems intuitively
obvious. We only have so much energy and each child obviously requires a substantial investment of this scarce commodity. That life span should be correlated to age at first birth seems less intuitive, however. Researchers are careful to point out that older mothers do not necessarily live longer just because they have fewer kids. Indeed, the
precise reasons for the importance of age are unclear.
It could be that if a woman is able to have children in the 11th hour, she is clearly one of the genetic elect. As the authors of the
Boston study put it, the ability to have kids after a certain age, say
40, may simply be a marker for longevity: Late pregnancy implies
late menopause, which in turn implies the later onset of age-related
disease such as Alzheimer's, heart disease and stroke. According to yet
another study, led by Jonathan L. Tully of Massachusetts General Hospital and published last month in Nature Genetics, when the ovaries of geriatric mice are engineered to grow eggs and secrete estrogen into
advanced old age -- the equivalent of delaying menopause in humans -- they remain strikingly youthful and robust.
It is also plausible that the timing of first pregnancy resets, or at
least plays interference with, a woman's biological clock. Mrs. Shandy
of the 18th century novel "Tristram Shandy" may have been the first to connect conception with timepieces: "Pray, my dear," she
inopportunely asked her aging husband, "have you not forgotten to wind up
the clock?" Winding up our biological timepiece sooner could trigger
early menopause and winding it up late in life could delay menopause and
rejuvenate middle-aged parents. If so, older mothers who serenely assert
that their children keep them young may be right.
Sadly, for men, one of the sacred tenets of evolutionary psychology -- that men are naturally more promiscuous in order to propagate the species -- may also be fatal. Married men with decreased fecundity live longer, and their longevity is in fact correlated to that of their spouse. And like their fruit fly counterparts, those men who invest heavily in reproduction while young can expect, on average, shorter lives. We always knew men should share in the costs and benefits of parenthood; now the British study confirms they do, in a somatic sense.
"Wee kill our selves to propagate our kinde," wrote 17th century poet John Donne. He was actually
alluding to orgasm, the "little death," which at the time was believed to
take years off men's lives. Read literally, however, Donne was expressing a
form of Darwinian logic avant la lettre.
As with most scientific research, the results of these studies will no doubt be modified. They are based on statistical associations, not the analysis
of deterministic processes. They imply that a marriage of nature and
nurture is involved in longevity -- and probably a big helping of chance.
Certainly there are women -- Rose
Kennedy and Queen Victoria immediately come to mind -- who have
huge broods at an early age and live to ripe old age.
And waiting until midlife to conceive is not necessarily the best way to ensure a successful pregnancy.
Besides, doing so also risks missing out on a few more IQ points! Another recent study, reported on at a meeting of the Society for Neuroscience in Los Angeles last November, suggests that women may get
smarter during pregnancy and lactation -- that is, if they are anything
like lab animals. Studies performed on rats showed that
brain structures called dendrites double during pregnancy and lactation, thus making learning more efficient. According to the team of researchers, led by Craig Kinsley of the University of Richmond, mothering rats learn mazes more quickly, make fewer mistakes and retain the new knowledge longer. The changes appear to mark the brain for a lifetime, suggesting that women's brains may be far more capable of change than those of men. Of course, some mothers have always believed this to be true.
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