Pregnancy in women aged 40 and older

SUMMARY Counseling patients about pregnancy at advanced maternal age is a difficult process. This is true both because our knowledge of the attendant risks is incomplete and still evolving, and because of the difficulties of assigning risks and addressing counterbalancing benefits for individual patients. There are a number of social and personal considerations involved in a decision to become a parent after the age of 40. Generally, older parents tend to be more mature, to be in stable and healthy marriages, and to have more financial and family resources to assist with the process of child rearing. Parents in their fifth decade, however, may complain of having less energy to devote to young children or may be at a stage in their careers in which they have less time for family participation than when they were younger. Also, grandparents, who can play a critical role in early childhood development, often have become too old to participate in that role or have died. All of these issues must be considered by parents contemplating late childbearing. A great deal has been written, much of it positive, even enthusiastic, about the quality of pregnancy and childbirth among older women. Nevertheless, much of the literature is difficult to interpret because of problems in controlling for confounding variables. In addition, much of the focus on so-called older women has been on those older than 35 years. In fact, the great majority of the medical literature concerning late childbearing relates to women between the ages of 35 and 40. The data that directly concern women in their fifth decade suggest that risks that began to accelerate after the age of 35 become considerably greater and increase more rapidly after the age of 40. Obviously, couples must decide what risks they are willing to accept and how these potential risks might be countervailed by the presumed advantages of parenthood relatively late in the reproductive years. There is convincing evidence to show that fecundity is decreased with advancing maternal age, and various forms of early pregnancy loss are increased. Thus, to delay childbearing results in a significant decrease in the likelihood of becoming pregnant or carrying a pregnancy to term. The possibility of genetic disorders is, as has been discussed previously, relatively easy to quantitate, and most age-related anomalies are amenable to prenatal diagnosis. It seems clear that women with underlying medical diseases, particularly hypertension and diabetes mellitus, contribute heavily to the excess morbidity and mortality associated with late childbearing. An unfortunate inference is often made from this information. That is, if a woman does not have any medical diseases at age 35, it is reasonable to delay childbearing further, based on the assumption that her risks will not increase. This is fallacious for two reasons. First, the likelihood of developing diabetes, hypertension, or other diseases that potentially complicate pregnancy increases with age, and if one is not diabetic at age 35, it does not mean one will not be at age 40 or 42. Second, some of the complications that contribute to risk are not identifiable until pregnancy or even labor begins. Consequently, some of the risk is not easily predicted by the state of prepregnancy health. A final issue in this regard must be addressed and that is the question of whether a woman older than 40 years who is in good health, has no history of infertility, does not smoke, and has favorable sociodemographic features is still at increased risk. Surely such a patient has a lower risk of adverse pregnancy outcome than a woman who embarks on gestation with a medical illness, a history of infertility or other gynecologic problems, smokes, or uses other drugs. Nevertheless, the best information available20 suggests that the healthy individual is still at increased risk on the basis of advanced age itself. Thus, the available data support the idea that pregnancy after the age of 40 is associated with decreased fecundity and fertility. The latter is contributed to by increased early pregnancy loss (probably due primarily to genetic abnormalities) as well as to maternal morbidity and mortality, low birth weight delivery, and other features of poor perinatal outcome. Although the existence of prepregnancy medical conditions clearly increases these risks, they appear to accrue even to women who are healthy, well nourished, and highly motivated before pregnancy. This notwithstanding, the great majority of pregnancies attempted after the age of 40 do eventuate in the term delivery of healthy fetuses. Each individual must be counseled so that she may make an informed decision about whether the potential risks of childbearing after the age of 40 are outweighed for her by the potential social and personal benefits.