Health

Racing the biological clock

Doctors re-examine the health risks of postponing motherhood

SHARON DOYLE DRIEDGER January 26 1998
Health

Racing the biological clock

Doctors re-examine the health risks of postponing motherhood

SHARON DOYLE DRIEDGER January 26 1998

Racing the biological clock

Doctors re-examine the health risks of postponing motherhood

SHARON DOYLE DRIEDGER

Dorothy Liehr did not feel ready to have children until she was nearly 40. For the first several years of their marriage, Liehr and her husband, Ralf, worked long hours to establish their careers as computer analysts. “We wanted to be more settled, more financially stable before we had children,” says Liehr, who lives in a small community 50 km north of Toronto.

But after she decided it was time to start a family, Liehr learned about the risks of a late pregnancy and wondered if she had waited too long. “Once I saw the statistics, I became worried,” she says.

“You look at the charts and say, ‘Oh.’ At 42, the chances were as high as 1 in 40 of a genetic defect—that scares you.” Liehr did suffer complications during her first pregnancy, but she gave birth to a healthy son, Raymond, in February, 1993, and a daughter, Eleanor, three years later.

‘We’re glad we waited,” says Liehr. “We can provide for the kids and we can handle things better than when we were in our 20s.”

Never before have so many women delayed parenthood until middle age. And never before have so many older women—seemingly more of grandmother age—become mothers: last week, the British press reported that 60-year-old Elizabeth Buttle of Wales became pregnant without the use of fertility drugs and gave birth to a healthy boy, Joe, on Nov. 20, making her Britain’s oldest mother. While such cases are still extreme, Statistics Canada says that in 1995 mothers over the age of 35 accounted for 12 per cent of live births, compared with fewer than five per cent in 1975. The trend flies in the face of conventional wisdom, and some current medical texts, which dangle 35 as the magic age limit for a first child. But an increasing number of women, facing a complex mix of social and economic pressures, wonder if they can safely postpone pregnancy well into their 40s. And now, some experts are beginning to say that the reproductive alarm need not be sounded so early. “In the olden days when women had 11, 12 and 13 children, women had babies right up until menopause,” says Dr. Kofi Amankwah, professor

of obstetrics at the University of Toronto.

One recent B.C. study shows that, although older mothers experience a higher incidence of caesarean sections, miscarriages and other complications, many of the problems are not caused by age. “The risk factor of age alone has been overstated,” says Dr. Jon Barrett, a specialist in maternal fetal medicine at Toronto’s Women’s College Hospital. “Much more important is the state of a woman’s health, family and genetic history.” It is a fact, he adds, that older women are more likely to have medical conditions that could lead to complications. But a healthy older woman is at less risk obstetrically than a younger woman who has an underlying disease.

Still, there is no question that a woman’s chances of giving birth to a baby with abnormal chromosomes increase with age. The risk of Down’s syndrome—one of several possible congenital defects—rises dramatically from 1 in 600 at age 30, to 1 in 285 at age 35 and 1 in 40 at age 42. Women over 35 are generally offered an amniocentesis—a procedure that involves injecting a needle into the womb and removing fluid that can be tested for genetic abnormalities. Why 35? “In a younger woman, whose risk of having an abnormal baby is 1 in 1,000, it doesn’t make much sense to have a procedure with a risk of miscarriage that is 1 in 200,” explains Barrett.

But some women, like Deborah Walden —who became pregnant for the first time two years ago at the age of 41—refuse to have an amniocentesis, because they do not want to lose what may be their only chance to have a child. "We talked and talked about it,” recalls Walden, who opted instead for a maternal blood screen, which is a blood test taken at 16 weeks of pregnancy that picks up about 60 per cent of Down’s syndrome babies. The former Toronto computer worker faced several anxious months of waiting after the genetic test indicated that her baby might have Down’s syndrome. “It isn’t definite,” says Walden. “It only gives you the odds, so we decided to hang in there. It was a miracle to start, and we thought it could end with a miracle, too.” In February, Walden gave birth to Melody, a sound and healthy baby girl.

In the B.C. study, researchers found that mothers over the age of 35 suffer an increased incidence of hemorrhage, diabetes, multiple births, prolonged labor and hypertension. They also tend to have more premature births and low-weight infants. ‘The most disturbing issue to me is the high risk of caesarean section,” says Ying MacNab, a statistician with the British Columbia Vital Statistics Agency and one of the authors of the paper. “It is quite an astounding ratio—1 in three women over the age of 35.”

MacNab reports that a follow-up study found “no good reason” for the high rate. “We see a gradual decrease in the late ’90s,” she adds. “So we are hoping the rate will go down.” Other experts are also at a loss. “Where there is no difference in complications,” says Barrett, “yet you’ve got a higher C-section rate, somebody is too anxious—probably the doctor and the patient.” Nor should older mothers necessarily suffer other complications, he says—if they are healthy. The problem, doctors say, is that as women age they tend to develop high blood pressure, diabetes and other medical conditions that could lead to a difficult pregnancy. “I feel better about a healthy 48-year-old patient who is pregnant, than a 26-year-old with diabetes who is pregnant,” says Amankwah.

Most doctors continue to monitor older patients very carefully. “There is unease and uncertainty when you get to the age of 45,” says Barrett. “Most would be sent to specialists who check blood pressure and watch the baby’s growth.” And researchers continue to study the effects of parents’ age on their offspring. “It seems babies born to older couples have a higher incidence of Alzheimer’s,” says Amankwah, pointing to new lines of research. “And children of an older father seem to have some increased risk of inherited diseases.” More positively, researchers found evidence suggesting that women who bear children after the age of 40 tend to live longer.

So what’s a woman to do if she wants to postpone baby-making? “Keep fit, eat a normal diet, don’t smoke and don’t drink too much,” advises Barrett. “If you keep yourself healthy and limit medical risk, then I don’t believe your pregnancy will be a much more serious risk than a younger mother.” But he also cautions that fertility decreases with age—most women may find that it takes longer to become pregnant. A few may not be able to conceive. “I have seen women who decided to delay having a family because of a career and then can’t fall pregnant,” he adds. “That is a tragedy.” Cautious couples might keep track of their fertility with sperm counts for potential fathers and hormone tests to ensure that a woman is ovulating normally. But they may want to monitor their energy levels, too. “Kids keep you active,” advises Liehr. “But you start to feel your age and can’t take those midnights.”