A cervical cap is a non-hormonal birth control method that you only use during sex - here's how it works

• A cervical cap is a method of birth control that you insert into your vagina to cover your cervix.
• You also need to line the cap with spermicide to kill any sperm that make it past the barrier.
• A cervical cap is about 86% effective, whereas the birth control pill can be up to 99% effective.

A cervical cap is a silicone device that's meant to block sperm from reaching your cervix in order to prevent pregnancy.

It's one of several examples of, what are called, "barrier method" birth controls that also include condoms, diaphragms, and sponges.

Cervical caps are relatively rare in the US - less than 1% of Americans have used one - and they're less effective than other, more common, forms of birth control.

Here's what you need to know about cervical caps and how to use them.

What is a cervical cap?

There are two main elements to a cervical cap:

1. The rubber cap - shaped like a dome with a thick brim around the edge - which you place over your cervix.
2. The spermicide cream - designed to kill any runaway sperm - that you use to coat the cap.

Spermicide: Spermicide is a substance made from chemicals like nonoxynol-9, which are designed to kill or immobilize sperm before they can enter your uterus.

You need to get a prescription from your doctor for a cervical cap. This is mainly because cervical caps come in different sizes and your doctor will need to do an examination to find out which size is best for you.

Cervical caps come in three different sizes, based on your birth history:

• Small: which is meant for people who've never been pregnant.
• Medium: for those who've had a miscarriage, abortion, or Cesarean section delivery.
• Large: for people who have undergone a vaginal birth.

How effective are cervical caps?

Cervical cap effectiveness varies depending on whether, or not, you've had a vaginal birth because giving birth stretches your cervix, making it harder to get a perfect fit. Here's the varying effectiveness of cervical caps and how they compare to other forms of birth control:

• Cervical caps: 86% effective if you've never given birth and 71% effective if you've had a vaginal birth
• Birth control pill: 99% effective when used correctly and 91% effective with average use (accounting for missed doses)
• Vaginal ring: 99% effective when used correctly and 91% effective with average use (accounting for mistakes like taking the ring out for too long)
• Condoms: 95% effective when used perfectly and 85% effective with average use (accounting for if it breaks or slips off during intercourse)

How to use a cervical cap

To properly insert a cervical cap, Frances Casey, MD, MPH, a professor of obstetrics and gynecology at Virginia Commonwealth University, recommends the following steps:

1. Wash your hands with soap and water.
2. Line the inside and brim of the cervical cap with spermicide. You should use about ½ teaspoon.
3. Get in a comfortable position with one foot on a chair, lying down or squatting.
4. Separate the lips of your vulva with one hand and with the other hand, squeeze the cap with the dome side and strap pointing downward.
5. Push the cap deep in your vagina and make sure your cervix is covered completely. You can do this by feeling around the edges of the cap.

You can insert a cervical cap right before sex. If you have sex more than once, leave the cervical cap in but put a new dose of spermicide in your vagina.

Also, be sure to leave the cap in for six hours after the last time you have sex so the spermicide can kill any remaining sperm that the cap may not have completely blocked.

"Do not leave it in for more than 48 hours," Casey says, as this can increase your risk of getting an infection like toxic shock syndrome.

The benefits and risks of a cervical cap

Like all forms of birth control, cervical caps have their pros and cons:

Benefits:

• You have complete control over how you use the cap, unlike other methods like condoms where your partner has more control.
• You don't need to keep refilling prescriptions, as each cap can last up to a year.
• You only need to use it when you have sex, unlike a daily pill that can be difficult to use perfectly if you're forgetful.
• You don't need to take any hormones, which may help you avoid side effects like mood swings or decreased sex drive.

Risks:

• Some people may have a hard time inserting and removing the cervical cap.
• They're less effective at preventing pregnancy than other birth control methods.
• Spermicide can cause vaginal irritation in some cases.
• It doesn't offer any protection against sexually transmitted infections.

Insider's takeaway

A cervical cap is a non-hormonal option for birth control that some people may prefer over other methods. However, it comes with higher risks of unwanted pregnancy and can be hard for some people to use.

The cervical cap can be a great option for someone who doesn't want to use hormones and wants to have control over their birth control method, Casey says.

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