Older Mothers Have Higher Risk of Miscarriage

From the WebMD Archives

June 26, 2000 --Three and a half years ago, the country was shocked by news from California that a 63-year old woman had given birth after undergoing fertility treatments and lying about her age. She claimed to be 50.

Although it serves as an extreme example, more and more women in the U.S. and elsewhere are choosing to become pregnant later in life than ever before, either naturally or through the use of fertility drugs.

But experts caution that women over age 35 are at a serious biological disadvantage compared with younger women and face more pregnancy-related risks.

"This is a dangerous trend, and women quite often have unrealistic expectations about fertility," says Mark Perloe, MD, director of reproductive endocrinology, infertility, and in vitro fertilization at Georgia Baptist Medical Center in Atlanta.

A new study in the June 24 issue of the British Medical Journal provides some sobering statistics to back up the warnings. The study of more than 600,000 women in Denmark who had a pregnancy between 1978 and 1992 shows a steady age-related rise in rates of miscarriage -- from 9% among women in their early to mid-20s to a whopping 75% among women age 45 and older. The risk of ectopic pregnancy -- a dangerous condition in which the fertilized egg implants outside the uterus -- and stillbirth also increased dramatically with increasing age of the mother.

"Our study shows an important increase in the risk of [miscarriage] and other types of fetal loss among women aged more than 40 years and that the increase is already considerable among those in their 30s," writes lead study author Anne-Marie Nybo Andersen of the department of epidemiology research at the Danish Epidemiology Science Centre in Copenhagen.

"Everybody knows someone who had a baby in their 40s ... but the curve from this study and others really shows that not only does the fertility rate drop dramatically beginning at age 38, the miscarriage rate rises, so that just getting pregnant is only half the battle," Perloe tells WebMD.

He says stories about celebrities such as Jane Seymour having children in their 40s may seem encouraging, but they disguise the fact that the majority of women in this age group who attempt pregnancy are unsuccessful. The average pregnancy rate for women age 40 and up is much smaller than the rate for women in their 20s. Also, the amount of time that a woman has been trying to get pregnant is a major factor and is often an indicator of problems that can impair fertility, such as endometriosis. The longer a woman waits to find out if there is a problem, the more her chances of pregnancy decline.

Perloe says blood tests are available for women age 38 and above to help them determine their likelihood of getting pregnant either on their own or with fertility treatments. Such tests can actually help predict the chance of age-related miscarriages so that women have a realistic idea of what they can expect. But, for many women, even hearing that their chance of a successful pregnancy is very low is not enough to discourage them from trying.

But could there be benefits to having kids at an older age that outweigh the biological disadvantages? Some experts think so.

"We think they are in a position to be better mothers because they know more and they pay more attention, etc," Mervyn Susser, MB, BCh, tells WebMD. Susser and colleague Zena Stein, MD, say teen-age mothers have a biological advantage because younger age is associated with better pregnancy outcomes, but compared with women in their 30s and 40s, teen-agers and even women in their 20s are usually not as mature or as financially stable as older women.

The reasons why women wait to have children are diverse, but many cite pursuit of higher education, busy careers, and lack of time to build solid relationships.

Naomi Pelzig, MD, didn't get married until she was 38. She had her first child six years ago at age 42 and her second at age 46.

"I realize in retrospect that I was really lucky," says Pelzig, now 48, a doctor who practices acupuncture and holistic medicine in Nyack, N.Y. She says though there is no question that plenty of women do get pregnant in their 40s, she thinks some women justify delaying pregnancy by looking to the well-publicized celebrity pregnancies and assuming they will have the same success.

"We need to let younger women know that they can't wait as long as we thought," Pelzig says. "Even though it's often not our fault, we have to make relationships and family as least as important as career."

But statistics confirm that women are indeed waiting longer than ever before to have children. Just last week, the state of Massachusetts released figures showing that in 1998 the majority of women who gave birth were age 30 and over. The state says this is the first time women over 30 have outdistanced younger women in birth statistics. In 1980, three times as many women who gave birth were under, rather than over, age 30. It is not known if the trend is as prevalent in other parts of the country as it appears to be in the northeast.

Andrea Kott, a 42-year old medical writer in Sleepy Hollow, N.Y, who had both of her children in her late 30s, says she thinks some women wait because they want to be in the best possible place in their lives before starting a family and want to feel that they have reached their career potential.

"For me, having kids was a reflection of being in a good personal place," she says. "Where I live, I'm not in a minority; most of my peers with young kids are around the same age as me." But she admits that staying fit and healthy is a priority when you're over 40 and have small kids.

Perloe, the fertility specialist, says while pregnancy at any age is a very personal choice, women need to know their risks and their chances of success early enough that they can keep all their options open.

"There are benefits for women who want to have kids early and there are benefits for women who want to have kids late, as well as disadvantages," he says. "But I think anyone entering into this ought to consider the ramifications of putting off having kids."

For more information from WebMD, visit our -->Diseases and Conditions pages on pregnancy.