How Does Birth Control Work?

The way birth control works depends on the method used. In general, birth control works by preventing sperm from joining with an egg—or fertilizing the egg. With contraceptives, such as the birth control pill and birth control implants, fertilization is avoided by preventing ovulation. Hormonal birth control also thickens the mucus on the cervix, which prevents sperm from reaching your egg, so pregnancy cannot occur. 

 

Some birth control methods work immediately, while others can take a few days or several weeks to take effect. That’s why it’s essential to talk with your doctor about your chosen birth control type so that you know what to expect and whether you need a secondary birth control method.

Birth Control Methods

• Physical Barriers – Physical birth control includes male condoms, female condoms, diaphragms, the birth control sponge, and cervical caps. Male condoms are most effective when used correctly, and they are usually easiest to use. Physical birth control methods range from 71-88% effective and should be used each time intercourse occurs. Both male and female condoms also offer some protection against STDs, while other physical barriers such as diaphragms do not.

• Birth Control Pill – The birth control pill is sold under many different brand names, but all work the same way. They contain hormones to stop ovulation. The pill must be taken every day at the same time each day to remain effective. When used correctly, birth control pills are 91% effective at preventing pregnancy. They can also offer numerous health benefits, such as lighter and more regular periods. In most states, a doctor’s prescription is required to obtain the birth control pill.

• Birth Control Patch – The birth control patch is a transdermal patch that is worn on the skin and replaced once weekly. It delivers the same medication as the pill, but may be more effective for women who often forget to take daily birth control.

• Birth Control Implant – With the birth control implant, or Nexplanon, you will have a small, matchstick sized implant placed in your arm. The implant releases hormones into the body over a period of up to 3 years. Maintenance is minimal, and the implant can be placed in a short in-person doctor’s visit. It is also one of the most effective birth control methods with up to 99% effectiveness in clinical studies. However, Nexplanon is more expensive than other birth control methods, usually costing about $400-$800.

 

• IUD – IUDs, or intrauterine devices, come in two different designs. Both fit into the uterus in the same way and provide long-term birth control, but one is a hormonal birth control method while the other is not. Hormonal IUDs last about 3-5 years and use the same hormones as the pill to block ovulation. Copper IUDs can last up to 12 years, and they prevent pregnancy with a physical barrier—sperm does not react well to copper, so they are effectively kept from fertilizing eggs. Copper IUDs can also serve as an emergency form of contraception. Both designs require an in-office procedure to be placed.

 

• Birth Control Shot – The birth control shot, also called Depo-Provera is administered by a nurse or doctor once every 3 months. It is immediately effective and works about 97% of the time. Many patients enjoy the shot, because it does not require daily upkeep and it can make periods much lighter—about half of users will get no periods at all while using the shot. However, there can be more side effects with Depo-Provera than other birth control methods, including weight gain, nausea, and headaches. It is also more expensive than the pill or the patch and requires quarterly trips to the doctor’s office.

 

• Surgery (Vasectomy and Tubal Ligation) – The only permanent methods of birth control are surgical. For men, the procedure is a vasectomy, which is a low-risk outpatient surgery in which the vans deferens (the tubes in the scrotum) are severed to keep sperm out of the semen. Men who have undergone vasectomies still experience normal arousal and ejaculation. Women may have tubal ligation surgery as a permanent form of birth control. During this procedure, the fallopian tubes are permanently blocked to prevent ovulation. However, this procedure is generally considered higher risk than a vasectomy. In addition, most women who opt for tubal ligation have already had children, since the procedure is irreversible.

 

• Emergency Contraception – Unfortunately, birth control isn’t always something that men and women think about until they need it. And sometimes, the heat of the moment can cause forgetfulness in utilizing proper birth control methods. Alternatively, birth control methods may fail when used improperly. For example, a woman may miss a dose of her birth control pill, making pregnancy more likely. That’s why emergency contraception is available in the form of the morning after pill. Emergency contraception can be obtained from the pharmacy without a prescription. It is effective in preventing pregnancy up to 48 hours after intercourse. For women over 165 pounds, however, the morning after pill may be ineffective. In these cases, the copper IUD may be the most effective form of emergency contraception, which can then serve as a long-term birth control method.

Conditions Treated with Birth Control

Some women will use birth control for reasons beyond pregnancy prevention. Many women with severe menstrual cramps, heavy periods, and irregular periods find that birth control helps to relieve these symptoms. In addition, hormonal birth control may be prescribed to manage the following conditions: 

• PCOS (Polycystic Ovary Syndrome)

• Endometriosis

• Severe Acne

• PMS (Premenstrual Syndrome)

Choosing Your Birth Control Type

The right type of birth control for your needs will depend on several factors. Because most birth control options will require a doctor’s prescription (or require a physical visit to the doctor to place the birth control device), you will likely work closely with your physician to determine what is best for your lifestyle and health needs as well as your budget. With most health insurance plans, the pill may be obtained without a copay, so it is often the most affordable option.

Possible Side Effects

Hormonal birth control is considered safe for long-term use in most women. However, women who smoke or have preexisting heart or circulatory conditions may need to consider alternatives, since hormonal birth control can increase the risk for blood clots, hypertension, and stroke. Still, the most common side effects of birth control are mild, and most will subside after using a selected birth control method for a few months. Some common side effects that you may experience with birth control include nausea, weight gain, sore or tender breasts, spotting between periods, lighter periods, and mood changes. In addition, most birth control methods will require some time to become effective. Therefore, you may need to utilize secondary birth control as you begin a new contraceptive type.