Older Mothers Have Higher Risk of Miscarriage
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.