jumping from a mechanistic decomposition to a policy recommendation ignores
the underlying causes of any changes in behavior. Why did contraceptive use rise
in the United States? Why are sexually active teens in Europe more likely to use
contraception? It is not obvious that teens in the United States have more information
or better access now than they used to. Nor is it obvious that information
or access is better for teens in Europe. If we randomly assigned some U.S. teens
to have greater access to contraception, would it affect the rate of childbearing
among these teens? Perhaps not. To understand more fully what is driving the
patterns in teen fertility that we observe, we need to go further and understand
why teens in some places or in some years are more or less likely to use contraception
or to abstain from sex.
Standard Models, Prescriptions, and Evidence
The standard economic model of childbearing considers an individual
who maximizes utility over children and other consumption subject to a budget
constraint (for example, Becker and Lewis 1973). Preferences are generally
assumed to be fifi xed, and explanations have focused on differences in constraints,
like policies making welfare more or less attractive, policies making abortion more
or less readily available, and policies increasing access to low-cost contraception.
Moffifi tt (1998, 2003) reviews the evidence on the link between welfare benefifi ts
and nonmarital childbearing, including teen childbearing. The general consensus
is that more generous welfare benefifi ts have a modest positive effect on rates of
nonmarital childbearing. However, the lower rate of teen childbearing in Europe
with its much more generous welfare system provides a counterexample and prima
facie case against the hypothesis that social support is largely to blame for high rates
of teen childbearing in the United States. It also appears that the redesign of welfare
reform in 1996 had only minor effects on rates of teen childbearing, at best (for
example, Kearney 2004; Grogger and Karoly 2005).
Levine (2004) reviews the evidence on the link between abortion policy and
fertility outcomes and fifi nds that restrictive abortion policies such as parental notififi
cation laws or mandatory delay periods are not associated with higher rates of
teen childbearing. In Kearney and Levine (2009), we examine expanded access to
Medicaid family planning services during the 1990s and early 2000s. We fifi nd that
it led to statistically signififi cant reductions in teen childbearing, on the order of a
4 percent reduction. But this effect is not suffifi ciently large such that one could
conclude that limited access to free contraception is a primary driver of teen
childbearing rates or that expanding access further would drive the rates down to
European levels, for example.