Since the birth control pill was first approved for contraceptive use in 1960, it—and the other forms of birth control that have followed—has become a symbol of freedom for women who want to choose when and if they have kids. But what happens when you decide to try to get pregnant after years of taking birth control?

Although there is limited data on how many sexually active people are using birth control today, the CDC has found a rise in the amount of people who are reporting the use of birth control in general. From 2015-2017, the CDC found that nearly 65% of people with uteruses ages 15-49 were using some kind of birth control at the time they were interviewed—a 5% increase from the previous reporting. Hormonal contraceptives are not only highly effective, but they can also reduce the risk of uterine, ovarian, and colon cancers; reduce menstrual flow; and can reduce pain during periods.

But perhaps because of how well hormonal birth control works, there are often concerns about fertility following the use of contraceptives. If something is between 90-99% effective at preventing pregnancy, how does it affect our fertility and pregnancy when we stop using them?

If you’re worried about how birth control affects your fertility, we’ve got answers for all of your questions.

How does hormonal birth control work?

There are several different types of hormonal birth control, including oral contraceptives, injectable progestin, skin patches, vaginal rings, and in-uterine devices.

Although hormonal contraceptives come in different forms, they function in similar ways. After they’re taken or inserted, they release synthetic hormones that cause your body to maintain a consistent hormone level. Without the rise in estrogen that typically happens during a menstrual cycle, ovulation will not occur. Additionally, hormonal birth control also makes the mucus around the cervix thicker to prevent the sperm from entering the womb.

Hormonal birth control is anywhere from 90-99% effective. The lower rates in the range come from what is called “typical use.” Since people can be forgetful, they’ve accounted for those missed pills and skipped injection appointments. Since the IUD and birth control implant are inserted by a medical professional and can work for a set number of years before replacement or removal, their low maintenance makes them highly effective.

Related: How to reduce stress while trying to conceive

What are the downsides of taking hormonal birth control?

Despite the efficacy of hormonal birth control, there are also risks that prevent people from taking them or cause people to discontinue use. These include:

  • A slight increase of breast cancer rates
  • Short-term decrease in bone mass with progestin injection
  • Extremely rare risk of heart attack (heightened with age and smoking)
  • Very rare risk of stroke (heightened with age and smoking)
  • Very low risk of blood clots for those taking formulations including estrogen (heightened in people who have underlying conditions with risks of blood clots)

And although research into the pill’s effects on mental wellness remain extremely limited, there seems to be a small risk of developing depression while on the pill. As always, you should consult with your doctor if you notice yourself developing any side effects while using contraceptives.

Related: I was not prepared for the rollercoaster that is trying to conceive

How is fertility affected by hormonal birth control?

Approximately 90% of fertile couples conceive within twelve months of trying. But if you’ve been using hormonal birth control in any form before trying to conceive, you’re likely to experience a temporary delay in conception.

The American Society for Reproductive Medicine compiled various studies on couples who had used birth control prior to conception and found the following conception rates for the first twelve months:

Despite a limited amount of data, numerous studies have found that any delay in pregnancy following the use of oral contraceptives seems to be temporary and limited to the early months. If you’re trying to conceive and are currently on hormonal contraceptives, you should plan a preconception health visit to talk to your doctor about your fertility. Fertility is a complicated and under-researched topic, and arming yourself with knowledge and resources will help to prepare you for what lies ahead.

A version of this post was published July 12, 2021. It has been updated.