Q&A: How does the Pill affect long-term fertility?

In the mid-1970s, The Oxford-Family Planning Association (FPA), studied more than 17,000 women who stopped using the Pill, a diaphragm, or an IUD (intrauterine device) in order to get pregnant. The return to fertility was measured as the time until delivery of an infant. The study reported a significant delay in fertility of up to 42 months for women who had never been pregnant and up to 30 months for women who had been pregnant before starting the birth control pill. However, the results of this study were suspect because there was no association between duration of pill use and the chance for fertility delay. The formulation of birth control pills in the 60s and 70s was also quite different from those in use today.

In 2009, another study looking at the same issue found that after women stopped taking the Pill, the pregnancy rate was 57 percent at three months, 81 percent at 12 months, and 86 percent at 13 months. This rate of pregnancy is simlar to what is seen in women who did not use birth control pill.