Past Pill Use Doesn't Lower Fertility
Study: Pregnancy Rate Same for Past Users, Nonusers of Oral Contraceptives
May 8, 2007 (San Diego) -- Women who stop the birth control pill and then
try to get pregnant succeed just as quickly as women who have not taken oral
contraceptives before trying to conceive, a new study suggests.
The impact that using the birth control pill has on future fertility has
been debated for years. Some studies have shown women have difficulty getting
pregnant once they stop oral contraceptives, while other research has found
they have an easier time.
"Studies have been mixed," says Maureen Cronin, MD, PhD, a
researcher for the new study, presented at the 55th Annual Clinical Meeting of
the American College of Obstetricians and Gynecologists. "The majority of
studies suggest there is a slight delay in return to fertility after using
birth control pills," she says, "and that within 6 to 12 months
fertility is normalized."
But her study found no such lag and no substantial differences in pregnancy
rates between pill users and nonusers. "We did the study to lay the
question to rest," says Cronin, the head of global medical affairs for
women's health care for Bayer Schering Pharma in Berlin. The pharmaceutical
giant, which makes two types of birth control pills, Yasmin and Yaz, funded the
In the past, some experts have also suggested that after taking hormones
such as the pill a woman shouldn't or couldn't get pregnant right away after
stopping. A delay in trying to conceive, some say, allows the body to get back
to normal. Cronin says her study also proves that notion incorrect. "Your
body does not need to 'recover' from the pill," she says.
Cronin's team followed 2,064 women for two years; all were participating in
the European Active Surveillance Study on Oral Contraceptives and had stopped
taking birth control pills to become pregnant.
One cycle after stopping the pill, 21.2% of the women were pregnant, Cronin
found. This is comparable to the naturally occurring pregnancy rate per cycle,
which experts say is between 20% and 25%.
A year after stopping the oral contraceptives, 79.4% of the women were
pregnant; again the rate corresponds with those reported in women planning a
pregnancy who had not used the pill.
In the study, the median time to conception was three months after stopping
the pill (half the women got pregnant earlier, half conceived later).
"The effect of age [on fertility] was not amplified by oral
contraceptive use," Cronin tells WebMD.
Nor did long-term use of the pill have a major impact on fertility, Cronin's
team found. While 79.3% of women on the pill less than two years became
pregnant in the year after stopping it, 81% of women on the pill more than two
years got pregnant in the first year after stopping it.