13 Things You MUST Know About Birth Control Pills If You Don’t Want to Get Pregnant — or Do!

Four of five sexually active women have used birth control pills. These are the facts their doctors hope they know.

1/13 View as List

How does birth control work?

There are basically two types of birth control pills, synthetic forms of the hormones progesterone and estrogen, which can be close to 100 percent effective at preventing pregnancy if used correctly. One type contains the female sex hormone progesterone and the other type contain a combination of estrogen and progesterone, explains Jill Rabin, MD, co-chief of the division of ambulatory care and Women's Health Programs-PCAP Services at Northwell Health in New Hyde Park, NY. The hormones work in different ways to prevent pregnancy. "Progesterone thickens the cervical mucus, making it difficult for sperm to penetrate, and it also makes the Fallopian tubes move slower so the egg and sperm don't get together quite as efficiently," she says. "It also makes the uterine lining hostile to implantation." A fertilized egg can't implant in a thin lining—it needs a soft cushy place to implant. Estrogen inhibits ovulation by suppressing the hormones responsible for ovulation. "If you interrupt this cycle, an egg won't come out and a steady state of estrogen interrupts it," Dr. Rabin says. Neither type of birth control pills protect against sexually transmitted diseases, which are on the rise (are you at risk for STDs?).

Are there any women who can't take combined birth control pills?

"A lot of people can't take estrogen," says Dr. Rabin, who is based in New Hyde Park, NY. The list includes women with a personal history of a blood clots, breast cancer, or heart disease, and smokers. Progesterone alone is safer in some women. These are the silent signs you're on the wrong birth control.

How long does it take for birth control to work?

"Some pills begin working within 72 hours and others may take three to five days to become effective," says Dr. Rabin. "I tell my patients to use condoms for the first week just to be safe." These are the secrets your vagina wishes you knew.

When should I take birth control pills?

This varies by type, Dr. Rabin says. "Progestin-only pills must be taken at the same time every day or your cervical mucus will start to thin and you could become pregnant," she warns. "You don't have to take combination contraceptives at the exact time every day, but doing so will make it become a habit." Many women find it helpful to keep their pill pack next to their toothbrush, so the two daily habits naturally happen at the same time. Ask your doctor or pharmacist for advice on when and how you should take your pill. (Here's how to save money on commonly used meds.)

What happens if I forget to take a pill?

"Take it as soon as you remember or take two the following day, and if you forget for two days in a row, it may be time to consider a long-acting form of contraception such as an IUD that doesn't rely on memory," says Dr. Rabin. And in the meantime, use condoms until you have another form of birth control in place. These are the clear signs you should switch to an IUD.

How effective is the birth control pill?

"When we talk about the effectiveness of the pill, there are two different answers," says Donnica Moore, MD, president of Sapphire Women's Health in Chester, NJ. "In a clinical trial or when women use it 100 percent correctly as directed, the pill is more than 99.9 effective. However when it comes to real-life effectiveness, the pill is about 91 percent effective," she says. "This means that 9 out of 100 pill users will get pregnant each year largely because it's tricky to remember to take a pill every single day."

Can anything interfere with the pill's effectiveness?

Certain antibiotics, anti-fungal drugs, and other medications including some so-called natural supplements such as St. John's Wort can affect how well the pill works, Dr. Moore says. "Any time you get put on medication or start taking a new supplement and are also on birth control, ask your doctor or pharmacist if there are any interactions with the new medication and birth control pill and if so, what they are," she says. If you have a stomach bug and have been vomiting or have diarrhea, birth control absorption can be affected. Back-up contraception may be required in these cases, according to Dr. Moore. (Here's why you might be getting chronic diarrhea.)

Does the pill have any side effects?

"The major side effects from too much estrogen are bloating and sore breasts, so if you notice that, talk to your gynecologist about a lower-dose estrogen pill," says Mary Jane Minkin, MD, Clinical Professor of Obstetrics & Gynecology at Yale University. "The major side effects from progestins (and there are a lot of different types out there) would be moodiness and irritability," she says. "If that happens, do talk to your gynecologist about switching to a different pill that would make you a bit less moody." These are the foods that boost your mood.

What should I do if I am on the pill and want to become pregnant?

Although you could just go off the pill, there are other considerations you'll want to discuss with your doctor. For example, you might not know your blood sugar runs high, and according to Dr. Rabin, the time to fix this is before you become pregnant. "You should also be taking prenatal vitamins even when still on the pill to maximize your health," she says. "Start prenatal vitamins, come off of the pill, see your doctor, and then get pregnant." Here's how to get pregnant, according to OB-GYNs.

How soon after stopping the pill can I try to conceive?

"Right away," says Michael Cackovic, MD, an obstetrician/gynecologist at Ohio State University Wexner Medical Center in Columbus. "As a matter of fact, we sometimes put women who are irregular and want to conceive on the pill to regulate their menses." The only way to know when you are ovulating is to get on a regular cycle, he adds. "Your fertility comes out kicking and screaming." Don't fall for these infertility myths.

1/13 View as List

Want to stay smart and healthy?

Get our weekly Health Reads newsletter

We will use your email address to send you this newsletter. For more information please read our privacy policy.