For some women, choosing the right method of birth control is a simple process, while for others, the decision might feel overwhelming. Either way, understanding the pluses and minuses of each option is key, and obstetrician-gynecologists from Yale Medicine Family Planning are experienced at helping women decide which kind of contraception makes the most sense for them.

Broadly speaking, birth control can be broken into three categories in terms of how well it prevents pregnancy. The most effective methods are male or female sterilization, intrauterine devices (IUDs, placed inside the uterus), and the arm implant. Medium protection comes from the hormonal pill, patch, ring, or injection. Methods like condoms, spermicide, withdrawal, and the rhythm method offer lower protection.

Aileen Gariepy, MD, MPH, has a chart in her office that she often uses to go over the different forms of contraception with her patients. “We know from large studies of women that the most important piece of information is how effective each type of birth control is,” she says. “And our patients are the best deciders about what to use, when to use it, and when to stop using it. Our counseling is patient-centered.”

Effectiveness is typically the first “lens” doctors and patients work through when discussing contraception, but it is not the only one, says Nancy L. Stanwood, MD, MPH, chief of Family Planning. Managing a health complaint, such as heavy periods, might be the leading concern for some women—and certain methods of birth control can help with that. “Birth control is not one-size-fits-all. We focus on what each patient wants and what is most important to her,” Dr. Stanwood explains. “We share our expertise to find the right match.”

When you are discussing birth control, your health care provider will also talk with you about prevention of sexually transmitted infections (STI), which condoms offer, convenience (IUDs and implants are “set it and forget it” for several years), side effects, and the cost and availability of each method. 

It is important to remember that for some methods reliability depends on proper use. For example, oral contraceptive pills need to be taken daily (and at the same time of day). “We walk patients through the pros and cons of all the types, helping them choose what is best for their lifestyle and health,” Dr. Gariepy says.

Contraception, also known as birth control, is any activity, medicine, or device used to prevent pregnancy for people having heterosexual sex. Birth control works by preventing the fertilization of an egg by sperm (conception). Some methods do this with a barrier between the egg and sperm (condoms, tubal ligation, vasectomy), others by stopping egg release, also called ovulation (pills, patch, ring, injection, arm implant), and others change the cervix and uterus to prevent sperm from getting through to the egg (IUDs).

There are multiple factors that influence if and when a woman or couple is ready to start a family, says Dr. Stanwood. “Women or couples can delay pregnancy until they're ready, which is particularly important for women who have complicated medical conditions and might need to make sure they're as healthy as possible before they plan a pregnancy,” she says.

The most effective forms of contraception (a failure rate of less than 1 percent, or fewer than one pregnancy per 100 women in one year) are as follows: 

• Vasectomy: This surgical procedure is a form of permanent sterilization for men.
• Tubal ligation: Also known as having one’s “tubes tied,” this surgical procedure is a permanent form of birth control for women.
• IUDs: These are the most common form of reversible contraception currently used by women worldwide. Some work with a hormone progestin for up to seven years and others with the metal copper for up to 12 years.
• Arm implant: The implant is a thin rod about the size of a matchstick that is inserted under the skin of your upper arm. It releases progestin, which prevents ovulation for up to five years. 

The next most effective tier (failure rates up to 10 percent, resulting in up to 10 pregnancies per 100 women in one year) includes the following: 

• Hormonal injection or "shot": Women receive shots that contain progestin (preventing ovulation) from their doctor every three months. The injection is given in the arm or buttock.
• Birth control pill: Also called “the pill,” this oral medication, taken daily, contains hormones that prevent ovulation.
• Hormonal patch: Replaced weekly, this is a small (5 centimeters by 5 centimeters) patch worn on the lower abdomen, buttock, or upper body. It releases estrogen and progestin into your bloodstream to prevent ovulation.
• Vaginal ring: The vaginal contraceptive ring releases progestin and estrogen into your bloodstream. The ring is about 5 centimeters in diameter and is made of a soft, flexible material. You insert it yourself, leave it in for three weeks, remove it for the week of your period, then replace it with a new one.

The third tier of methods in terms of effectiveness (failure rates may be as high as 20 percent, resulting in 20 pregnancies per 100 women in one year) include barrier methods, which physically prevent sperm from reaching an egg. Condoms (male or female), as well as spermicides and sponges, can be purchased at drug stores, while the cervical cap and diaphragm require a fitting by a clinician and a prescription.

Here are more details: 

• Male condom: Worn on the penis, the male condom is made of a thin layer of latex or a natural material such as sheepskin. (Latex condoms help prevent pregnancy and STIs; natural kinds help prevent against pregnancy, but not necessarily STIs.) Condoms keep sperm from getting into a woman’s body and can only be used once.
• Female condom: Worn in the vagina, the female condom is a thin plastic pouch that helps prevent sperm from getting into a woman’s cervix. It is sold with a lubricant in drug stores and can be inserted up to eight hours before sexual intercourse. It also protects against STIs.
• Fertility awareness-based methods: Also known as natural family planning or the rhythm method, this method involves avoiding sex on the days you are most fertile. Ovulation prediction kits, monitoring body temperature, and watching for changes in cervical mucus (which can signify oncoming ovulation), as well as keeping track of the menstrual cycle, can help identify the most and least fertile days.
• Diaphragm and cervical cap: Placed in the vagina, these cover the cervix to stop sperm from reaching an egg. Both require having your doctor fit you for the right size; you’ll be given a prescription to pick up at your pharmacy. These barriers are most effective when used with a spermicide.
• Spermicide: These products, which are available as foam, gel, cream, suppository, or tablet, contain a chemical that kills sperm. They are placed inside the vagina no more than an hour before intercourse. You can use spermicide in addition to a diaphragm, cervical cap, or male condom.
• Sponge: The contraceptive sponge releases spermicide when inserted into the vagina. It works for up to 24 hours and must be left in the vagina for at least six hours after the last act of intercourse before being removed and discarded. 

Available in a variety of forms, hormonal contraceptives prevent pregnancy by preventing ovulation and thickening cervical mucus to help block sperm.

Here is more information about birth control pills: 

• Combined oral contraceptives: Often called “the pill,” these oral contraceptives contain the hormones estrogen and progestin. Combined in this way, they prevent ovulation and make the cervical mucus thick and sticky, so it is more difficult for sperm to navigate. The pill must be taken at the same time each day to be effective.
• Progestin-only pill: Also known as the “mini-pill,” this version contains progestin only. It is taken daily and thickens the cervical mucus, which prevents sperm from reaching the egg. The mini-pill is often used by mothers who are breastfeeding because it doesn’t contain estrogen, which can interfere with lactation.

Other forms of hormonal contraception include the patch, implant, injection, and vaginal ring.

Intrauterine devices must be placed inside the uterus through the cervix by your health care provider. They are typically about an inch and a half long. Your doctor can remove an IUD at any time, and you can get pregnant as soon as it is taken out.

Intrauterine devices fall into two main categories: 

• Hormonal IUDs: These devices (made of soft, flexible pieces of plastic shaped like a ‘T’) release progestin, which thickens the cervical mucus to prevent sperm from reaching an egg. Depending on the brand, one device can remain in place and offer protection for three to seven years.
• Copper IUDs: This type doesn’t contain hormones, is also flexible and ‘T’-shaped, but is coiled with a small amount of copper. The copper triggers a change in the cervix and uterus response that makes it difficult for the sperm to move. One device can offer protection for up to 12 years. 

When it comes to deciding which IUD is best, Dr. Stanwood says it depends on what women want their periods to be like. “Women with normal periods can safely use the hormonal IUD or the copper IUD, but if women have very heavy, crampy periods, they're better off with the hormonal IUD,” she says. 

“With the hormonal IUD, women generally find that their periods get lighter, shorter, and less crampy. Some of them might find that their periods stop. It’s totally safe to have a period stop when we know why.” 

Emergency contraception reduces the chance of pregnancy after you have unprotected sexual intercourse.

There are two main options: 

• Having your health care provider insert a copper IUD within five days of unprotected sex. The copper, which is released into the uterus and fallopian tubes, makes it hard for sperm to swim well enough to reach an egg.
• Taking a contraceptive pill (different from “the pill”) up to five days after unprotected sex. Several different types of emergency contraception pills are available in the U.S.; some are sold over the counter while others require a prescription.  

Most forms of birth control are generally considered safe, but women and couples should be aware of the various side effects and risks for each. For example, people with a latex allergy should avoid certain barrier methods (latex male condom), as they could cause a severe reaction. Oral contraceptives pose a small increased risk of developing blood clots, stroke, or heart attack, but these risks are lower than the risk of these complications in pregnancy.

“Birth control pills are extremely safe. It’s probably the best studied medicine ever in humanity,” Dr. Stanwood says. “Any medicine has some pros and some cons, and the benefits of the pill outweigh the risks for healthy women.”

IUDs are also safe and effective. “They're absolutely safe,” says Dr. Gariepy. “Not everybody likes them, and that's OK.” Some women mistakenly believe getting an IUD means it must stay in place for several years, which isn’t the case, she notes. 

“You can have it in for a month, and if you don't like it, we'll take it out. You can have it in for two years and then decide it's the right time to be pregnant and we can take it out. It doesn't affect future fertility.”

The obstetrician-gynecologists at Yale Family Planning are experienced and skilled at helping women and couples understand and choose the method of birth control that’s right for them. In particular, they see women who have complex medical conditions that can mean some contraceptives are not safe for them. Considering medical issues, patient values and past experience, Yale Family Planning physicians specialize in complex contraceptive counseling.

“A lot of patients come to us after having tried other methods of birth control they weren’t satisfied with and they're looking for an in-depth conversation. That’s one of our great joys—to help them understand what their safe choices are,” Dr. Stanwood says. “We're all about education and partnering with our patient to find the best method for her.”