Prevention of unintended pregnancies by using emergency contraception: the differences between levonorgestrel and ulipristal acetate. A theoretical model using data from a survey on the use of emergency contraception in Spain, 2017.

OBJECTIVE: To estimate the differences in unintended pregnancies avoided using either levonorgestrel (LNG) or ulipristal acetate (UPA) emergency contraception (EC).

DESIGN: Cross-sectional study.

SETTING: Survey carried out in Spain.

PARTICIPANTS: 1000 Spanish women reporting unprotected sex in 2017.

MAIN MEASUREMENTS: EC use, reasons for not using EC, calculation of the number of unintended pregnancies avoided.

RESULTS: 39% of Spanish women having had unprotected sex used EC. 61% of those women did not use EC and 11% did not know the existence of this resource. In 2017 the use of EC prevented 101,271 unintended pregnancies. If instead of using LNG every woman had used UPA another 15,979 additional pregnancies could have been prevented.

CONCLUSIONS: If all Spanish women having unprotected sex used EC we could expect a significant decrease in the number of unintended pregnancies and abortions. Using UPA instead of LNG would have a greater impact on that reduction with the corresponding benefit for women and society as a whole.