Epidemiological Aspects Of Parenthood: A National Survey Of Family Growth
From a presentation at a symposium titled, "Infertility in the Older Male Desiring Children" held at the annual meeting of the Society for the Study of Male Reproduction.
Presenter: Paul Shin, MD,
Urologic Surgeons of Washington,
In recent years, the media have profiled several high-wattage celebrities in their late 30s and early 40s who are having children. The trend toward delayed marriage and parenting does not appear limited to Hollywood. Data from the 2000 census and the most recent National Survey of Family Growth (NSFG) reflect this pattern as well.
Adults aged 35-44 account for the largest portion (16%) of the population stratified by age. Together with adults aged 45-54 (13.6%), they represent the tail end of the “baby boom” generation. These are the ages when fertility problems are likely to become manifest.
Begun in the 1960s, the NSFG provides a comprehensive look at families and relationships across racial and socioeconomic lines. Between 1970 and 2002, when the last survey was done (12,571 respondents), the average age at first marriage for women has increased by almost five years. The average maternal age at first birth jumped from 21.4 years to 25.1 years.
Additionally, the percentage of first-time mothers aged 30 or older leaped from 3.9% to 25.1%. This shift has been accounted for by the increasing numbers of women completing their education, entering the workforce, and establishing careers.
With data showing an overwhelming trend toward an aging population trying to conceive, the intuitive argument would be that fertility rates would be falling because of advancing maternal age. The opposite, however, appears to be the case.
Stephen and Chandra recently published a paper showing that the fertility rate, as defined by the NSFG, is falling. Further muddying the waters is that the impaired fecundity rate appears to be on the rise. Why the difference? Both data points (fertility rate vs. impaired fecundity) are derived from the questions in the NSFG.
According to the survey, a woman is infertile if she has: A) not conceived in the past 12 months, B) is between the ages of 15-44, C) is married, D) is not surgically sterilized, E) is sexually active and has not been using contraception in the past 12 months. By using this definition, the rate of infertility in the United States dropped from 8.5% in 1982 to 7.4% in 2002.
It should be noted that the infertility rate according to these criteria is a constructed measure, i.e., there is no question in the survey that directly poses the question of whether or not the participant is trying to conceive.
A woman is defined as having impaired fecundity if: A) she has a prolonged (36-month) period of infertility, B) it is physically impossible for her or her partner to achieve a pregnancy, and C) it is physically possible for the couple to achieve pregnancy, but difficult. When taking these criteria into account, the rate of infertility (15%) seems to be on the rise and is also more consistent with what would be expected.
Regardless of how infertility is defined, the overall population data are clear—as a society we are getting married and starting families later in life. Urologists must remain aware of how the patient population is evolving and, above all, tailor treatment options for the individual couple.