Oral Contraceptive Myths and Facts Part 2: Scheduling Issues

Recently, we discussed the endocrine system, a system of glands that produce biochemical substances known as hormones. These include sex hormones, which play an important role, not only in pregnancy, but also in events leading to it. Oral contraceptives, also called birth control pills, consist of hormones that interfere with the signaling between hormones and the ovaries. In this series, we are discussing oral contraceptives from various angles, beginning with some common myths and the facts that resolve those myths. This is part two of the myths and facts component. Let’s start with the topic of the scheduling of birth control pills.

Myth: You must start a new packet of birth control pills on a particular day of the week, such as a Sunday, after completing your period.

Fact: Although you should start a new packet of birth control pills 28 days after you started the previous packet, and thus on the same day of the week as when you started the previous packet, your ovaries do not know which day of the week it is. If you are beginning oral contraceptives for the first time, or after a gap, you should start the first packet the day that the heaviest bleeding is beginning to subside. For many women this may be be the second or third day of the period. You should discuss the start time with your gynecologist.

Myth: You needs to stop taking birth control pills a few cycles before you plan to get pregnant, in order to clear your body of the oral contraceptive hormones.

Fact: Your body does not need time to “clear” itself of birth control hormones. Within days of stopping the pills, the normal communication between your ovaries and brain resume. If you stop the pills at the end of a packet, you will experience the normal withdrawal bleed, after which you could become pregnant. Although it’s common for it to take a few weeks to a couple of months before conception occurs, you cannot depend on that. If you do not wish to initiate pregnancy within a couple of weeks after stopping the pills, then you should begin using a different contraceptive method, such as condoms, until you are ready.

 Myth: You cannot take oral contraceptive for the entire span of your reproductive years. There is a time limit, beyond which the pill is unsafe.

Fact: There is no limit in terms of how many years you can be on the pill. Some women take oral contraceptives from their teens until menopause and pause only to get pregnant, then resume after each pregnancy. Some women never even pause, because they never decide to have children.

Myth: It doesn’t matter what time you take the pill, as long as you take it each day.

Fact: To prevent the hypothalamus from releasing GnRH and the pituitary from releasing gonadotropins, it is important that the concentrations of hormones from oral contraceptives never fall below certain levels. Thus, for oral contraceptives to work reliably in preventing pregnancy, you need to be extremely dedicated to taking them correctly. This means on the correct schedule, which is one pill per day, and, importantly, each day at the same time without varying more than an hour or so from that selected time. Taking one at, say 8:00 in the morning on Sunday and next one at 6:00 in the evening on Monday would elevate the risk of pregnancy, since the contraceptive hormone levels in your blood could dip low enough for your pituitary to send a burst of gonadotropins just at the wrong time.

Myth: You will gain a lot of weight, if you go on the pill

Fact: Side effects of oral contraceptives often include changes in weight, including weight gain, but notable increase in weight is fairly uncommon among those taking birth control pills. On average, women gain 0.5 to 1.0 kilogram, or 1 to 2 pounds, after going on the pill.

In our next segment, Oral Contraceptives Myths and Facts Part 3, we’ll address the issue of whether oral contraceptives are good for all women, or whether certain women should avoid these agents or take them just under certain circumstances.

David Warmflash
Dr. David Warmflash is a science communicator and physician with a research background in astrobiology and space medicine. He has completed research fellowships at NASA Johnson Space Center, the University of Pennsylvania, and Brandeis University. Since 2002, he has been collaborating with The Planetary Society on experiments helping us to understand the effects of deep space radiation on life forms, and since 2011 has worked nearly full time in medical writing and science journalism. His focus area includes the emergence of new biotechnologies and their impact on biomedicine, public health, and society.

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