Indiana University SPEA Edward J. Bloustein School of Planning and Public Policy University of Pennsylvania AIR American University

Panel Paper: The Intensive and Extensive Margins of Contraceptive Use

Thursday, November 12, 2015 : 9:30 AM
Merrick II (Hyatt Regency Miami)

*Names in bold indicate Presenter

Adam Thomas1,2 and Quentin Karpilow2, (1)Georgetown University, (2)Child Trends
It is well known that some contraceptive methods are better than others at mitigating the risk of pregnancy. However, few studies have rigorously examined the implications of this variation in contraceptive efficacy for the high rates of unintended and nonmarital pregnancy in the United States. As an example, while the risk of pregnancy during the first year of use is more than 20 times higher among women who rely upon the pill than among women who use long-acting reversible contraception (LARC), it remains unclear to what extent aggregate rates of unintended and nonmarital pregnancy would be affected if a portion of pill users were to begin using LARC methods. We address this gap in the literature by using the FamilyScape 3.0 simulation model to compare movements along two different margins of contraceptive use: the extensive margin, which captures the decision as to whether or not to use contraception; and the intensive margin, which captures the effects of using progressively more efficacious methods. In tracing out the intensive margin, we also study the effects of reductions in method discontinuation and improvements in the correctness and consistency of method use. Our simulation results suggest that movements along the extensive margin of contraceptive behavior are much more impactful than equally sized movements along the intensive margin. For instance, we find that, even under an unrealistically conservative set of assumptions, the number of nonmarital pregnancies would be reduced by more than twice as much if a share of unmarried non-contracepting women were to begin using condoms than if an equal number of unmarried pill users were to switch to LARC.  We also find that the impact on the nonmarital pregnancy rate would be only marginally larger if non-contracepting women were to begin using LARC than if they were to begin using the pill. These results suggest that, as they decide how to allocate scarce resources, policymakers and practitioners should bear in mind that increases in LARC use are likely to have significant impacts on fertility outcomes only if they are driven by meaningful reductions in noncontraception.