Association Between Women's Use of Long-Acting Reversible Contraception and Declining Abortion Rates in New Zealand

摘要

Background: To investigate the hypothesis that increased uptake of long-acting reversible contraception (LARC) by women played a role in the declining abortion rates observed in New Zealand between 2008 and 2014. Methods: This quantitative ecological study analyzed routinely collected national data pertaining to abortion numbers, contraceptive prescriptions, and census population estimates for the period 2004-2014. Annual prescription and prevalence rates (per 1000 women) were calculated for short- and long-acting methods to investigate changes over time. Poisson's regression was used to (1) test whether the abortion rate changed by year; (2) whether 2010 (when the contraceptive implant became subsidized) was a significant point of change; and (3) test the relationship between declining abortions and patterns of contraceptive use. Results: Estimated LARC prevalence increased from 2009 to 2014, with a corresponding decrease observed in prescription of short-acting methods. The declining abortion rate accelerated each year from 2008 to 2014 (with a faster decline from 2010 to 2014), but 2010 was not a significant point of change. Three factors had statistically significant associations with declining abortion rates (p < 0.01): year (acting as a surrogate for all social changes), women's use of the levonorgestrel (LNG)-implant, and the combined model: use of the LNG-implant and copper intrauterine device (CuIUD) had the best fit (using Akaike's Information Criterion), indicating that this variable explained more of the year-to-year variability in abortion rates. Conclusions: The shift toward women's increased use of the two publically funded LARC methods (LNG-implants and CuIUD) was significantly associated with the declining abortion rates in New Zealand.