Popping the Pill: do you know how it works?

by Christie Matheson

More than 10 million women in the United States use birth control pills (also known as "the Pill"), according to a spokesperson for Planned Parenthood. Although women are grateful for this relatively simple form of contraception most of them readily admit that they don't know much about how the Pill actually works.

"A 'false pregnancy' was the old way of describing how birth control pills work, and that's still what many people say," says James McCarrick, MD, PhD, an obstetrician and gynecologist with the Palo Alto Medical Foundation. "But that's not accurate."

McCarrick explains that the "waxing and waning"of women's hormone levels causes the ovulation cycle. Birth control pills provide a steady level of hormones, and this steady hormonal state suppresses ovulation.

"The majority of women could use any Pill and be fine in terms of preventing pregnancy," McCarrick says. "There are dozens of effective Pills out there." Most birth control pills contain two hormones, estrogen and progestin.

Estrogen

The same kind of estrogen is in "all the low-dose pills, which 99.99% of [Pill-taking] women in the United States use," says Cheryl Walker, MD, assistant professor of gynecology and obstetrics at Stanford University Medical School. Walker says low-dose estrogen pills contain 20, 30, or 35 micrograms of estrogen. The exact dose of estrogen may have an impact on the kind of side effects you experience.

Some women should not take pills with estrogen, McCarrick advises. Women who are breastfeeding, have a history of blood clots, or have high blood pressure may be better off with a progestin-only pill, which has a slightly lower efficacy level than the combination pill.

Progestin

Different brands of the Pill may contain one of five progestins, says Walker. Because women differ in the kind of progestin found naturally in their bodies, McCarrick says, one variety of progestin can have different side effects on different individuals.

Monophasic vs. triphasic

Within the family of estrogen-containing pills there are two main types: monophasic and triphasic. As the names suggest, monophasic pills provide the same level of hormones throughout the pill cycle. Triphasic pills also induce a steady state of hormones, but at three different levels during the cycle. McCarrick says the preference for monophasic vs. triphasic Pills lies with the individual, and he stresses that they are equally effective for pregnancy prevention.

"Work with your doctor to figure out which one might be right for you," suggests Holly Hughes, RN, a staff nurse at the Brigham Ob-Gyn Group in Boston. "Just because someone else had a great experience with a certain kind of Pill doesn't mean you will."

\"There are fewer side effects now than there used to be because the Pill today contains a much lower level of estrogen,\" says McCarrick, who adds that the hormone levels in pills of yesteryear were \"five to twenty times greater than what they are today.\" Lower hormone levels usually mean fewer side effects, but side effects do still occur.

Negative side effects

\"The most common complaint I get is about breakthrough bleeding, which can be annoying,\" says Hughes. But, she reminds new Pill-takers, \"you are changing your hormone levels, so give a new type of Pill at least three months while your body adjusts.\"

Other possible side effects include headaches, nausea, breast tenderness, and bloating. If the negative side effects last for more than three months you should talk to your doctor and consider changing brands.

Positive side effects

Many people experience skin improvements.

\"I talk to my patients about the symptoms they are most concerned about and try to prescribe a kind of Pill that will minimize those symptoms,\" McCarrick says. But because of individual differences you can never be sure, he says. \"If you try one and it's not right for you, there are plenty of other options to try.\"

If, like many women, your monthly pill pack contains three weeks worth of active pills and one week of placebo pills, you have what seems like your period every month. "It's actually not a period; it's a bleeding event that occurs because you stop taking hormones," says McCarrick. Because ovulation has been suppressed for three weeks, you won't ovulate during that week. However, "if you waited 10-14 days before resuming taking active pills, your body would get ready to ovulate again."

You can decide to skip the placebo pills and continue taking active hormones, in which case you won't bleed each month. "That's a great option. You can tailor your pill schedule to fit your lifestyle," Walker says. "But you should try to bleed at least every three months or you may experience some discomfort," she adds.

Taking a week off after three weeks of active hormones is part of a normal Pill cycle, but skipping days in the middle of the three weeks is not a good idea. "If you have been taking active pills for four months and you miss a day or two, you won't ovulate," McCarrick says. But he says that if you skip a couple days in the middle of only three weeks of suppression, "you could have breakthrough ovulation."

When you take the Pill, it makes the lining of the uterus hostile to egg implantation and the mucus in the cervix tough for sperm to swim through. According to Walker, these benefits go away if you miss a day, increasing your risk for pregnancy.

If you do miss a Pill, take it as soon as you remember, and double up if you don't remember until the next day. Walker recommends using another method of contraception for at least two weeks if you do skip an entire day.

You can't get birth control pills without a prescription, so you have to see a doctor at some point. Be open with your physician so that you can make the best decision possible about birth control pills. Women with certain conditions should not take the Pill, and McCarrick reminds women to tell their doctors about any medications they take. "Don't just tell your doctor about your prescription medications," he says. "Mention any over-the-counter or herbal medications, too, because they might have an interaction with the Pill."

All birth controls on the U.S. market "are effective and safe," Walker says. "If you are on a Pill and you're happy, don't change it," she adds. But if you experience problems and side effects, speak up. There may be a Pill out there that's better for you.