A recent article in Adolescent & Family Health (AFH) asserts that increased abstinence accounted for most, and in some cases all, of the declines during the early 1990s in pregnancy rates and birthrates among women aged 15-19.1 Authors of the AFH article, and materials in support of the article’s conclusions produced and widely distributed by The Physicians’ Consortium, claim that this new analysis compensates for “errors” contained in earlier research on this subject by The Alan Guttmacher Institute (AGI) by relying on a more sophisticated methodology than that used by AGI.
AGI stands by the conclusions of its analysis that roughly one-fourth of the drop in teenage pregnancy rates between 1988 and 1995 resulted from increased abstinence, and approximately three-fourths resulted from more effective contraceptive use among sexually experienced teenagers.2 AGI’s methodology for measuring the factors contributing to pregnancy rate declines follows the consensus reached at a meeting convened by the National Institute of Child Health and Human Development (NICHD) to examine this very issue. This meeting involved researchers from AGI, the National Center for Health Statistics (NCHS), the Urban Institute, Child Trends and the National Campaign to Prevent Teen Pregnancy. And despite The Physicians Consortium’s charge that AGI’s study was not externally reviewed, it was in fact reviewed and revised based on comments from researchers at NICHD, Child Trends and NCHS.
A variety of researchers, using different time periods, data sets and approaches, have examined teenage pregnancy declines and, like AGI, all conclude that both increased abstinence and improved contraceptive use played significant roles. Indeed, even the AFH study, if read closely enough, shows that both reduced levels of sexual activity and reduced pregnancy rates among sexually active young women contributed to the decrease in teenage pregnancy rates and birthrates.
However, the AFH study’s bottom-line conclusion—that increased abstinence is responsible for the entire decline in birthrates among unmarried teenagers and most of the decline in pregnancy rates—is inaccurate and misleading because of at least four significant methodological flaws in its analytical approach:
1) Separating teens by marital status ignores when and why teenagers marry and leads
to inaccurate conclusions: The AFH article and its presentation by The Physicians
Consortium inappropriately treat unmarried teenagers as a separate population from
married teenagers, with distinctly different behaviors and birthrates and pregnancy rates.
In fact, these are not independent groups of teenagers: Many teenagers marry while they
are pregnant, so that nonmarital conceptions become marital births. As a result, changes
in the behavior of unmarried women (fewer pregnancies, or fewer pregnant women
deciding to get married before giving birth) can appear as changes in marital birthrates
and pregnancy rates—even when there is no change in behavior among already married
women. AGI researchers discussed these interrelationships and appropriately did not
separate teenagers by marital status in their analysis.
2) Analyzing birthrates alone ignores the impact of abortion and obscures declines in
unintended pregnancy: The birthrate analyses presented in the AFH article are
inadequate because they do not take into account changes in the proportion of
pregnancies ending in birth vs. abortion, which obscure improved prevention of
pregnancy by sexually active teenagers. The Physicians Consortium presents the
apparent rise in birthrates among sexually active unmarried teenagers as evidence of a
failure of contraceptive use when, in reality, it results from fewer abortions among
unmarried pregnant teenagers and fewer marriages among those who are giving birth.
AGI researchers tested the impacts of decreasing proportions of teenage pregnancies
ending in abortion and appropriately focused further analysis on factors accounting for
the changes in the underlying teenage pregnancy rate.
3) Using data collected in 1995 for 1991 behavior may introduce recollection bias: In
order to compare behavior in 1991 and 1995, the AFH study relies on women’s
recollection of sexual behavior extending as far back as four or more years, and places
those reports on an equal footing with data collected in 1995 about recent experiences.
However, many people report an earlier age for their first sexual experience in
retrospective reports than they do when interviewed closer to the time of the event. Such
a reporting bias would create the illusion that the decrease in sexual activity among
unmarried teenagers between 1991 and 1995 was larger than it actually was. In contrast,
the AGI analysis focused on survey data from 1988 and 1995 in order to take advantage
of information gathered in similar ways at both points in time, and relied on a relatively
short recall time, ensuring greater accuracy.
4) Ignoring available data and failing to investigate possible changes in sexual behavior
and contraceptive practice among sexually experienced teenagers weakens
conclusions: Whereas AGI’s analysis measures the impact of abstinence (defined as
never having had sex) as well as four different measures of the frequency and continuity
of sexual behavior, the AFH study focuses simply on changes in the proportions of
teenagers who had had sex within the past year. Further, the AGI analysis assesses
the contributions of various measures of contraceptive use towards declines in the teenage
pregnancy rate among sexually experienced young women. The AFH analysis ignores
available data and does not investigate the reasons behind those declines. In contrast,
AGI’s analysis estimates the relative contributions of both abstinence and behavior
change among those who had had sexual intercourse, including the frequency of sexual
intercourse, levels of contraceptive use and the types of methods used.
Future research, relying on newer data, will shed light on whether and how these patterns may have changed in the late 1990s and the current decade. The AGI analysis, however, currently offers appropriate and more complete answers regarding why teenage pregnancy rates and birthrates have declined.
For a background document providing a more in-depth analysis of the AFH article, please contact Rebecca Wind at 212-248-1953.