How Do Birth Control Pills Work?

WorriedWilma (19) writes: Here’s my situation. I’m thinking I’m probably not pregnant, but I don’t completely understand how the pill works, I guess:
-I have been taking Desogen (specifically Apri), the birth control pill, for a year.
-I missed 1 pill on 12/12.
-I didn’t realized I missed it until a week later and therefore did not take an extra to make up for it like you are supposed to.
-My period started 12/6 and ended 12/09 (it was about 4 full days long, which is usual for me).
-I had unprotected sex on 12/10, 12/11, and 12/12.
-I took my regular pill beginning on 12/11 as directed, missing only 12/12.
-I’ve been having a lack of appetite for the last three days (12/23, 24, 25) and my abdomen does not hurt like when I get cramps, but feels clenched.

I have also been more emotional than usual.

The reason I’m concerned is mostly the sex on 12/10 because my period was over (the bleeding was over) but I wasn’t supposed to start my next pack of pills yet (and didn’t).

I am also concerned about the sex on 12/11, since I missed the pill that day.

Does the pill prevent me from ovulating strictly each day (like, pill A prevents ovulation on Day 1, pill B prevents it on Day 2, etc.) or is it a general taking it prevents ovulation overall (so if I miss 1 day I probably didn’t ovulate that day).

I’m not supposed to get my next period until January 3, so I can’t take a pregnancy test till around then and any insight is appreciated!

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Dear WorriedWilma,

You should be fine. If you’d skipped two pills back to back, then I would be worried. Yes, you should have taken two pills on the day after you missed the one, but you should still be “safe.” Birth control pills are a bit complicated. We can’t really say that one particular pill made anything not happen or made anything happen. It’s really more of the cumulative effect caused by taking regular birth control pills. Birth control pills are basically trying to disrupt the auto pilot control within your body, and they are trying to establish the “new norm.”

I would still recommend taking the pregnancy test – probably first thing in the morning of January 8 for best success.

Good luck!

Hannah

Ps: Here’s some basic information on how birth control pills work. Excuse the technical jargon :)

How Do Birth Control Pills Work?

Birth control pills prevent pregnancy through several mechanisms, primarily by stopping ovulation. If no egg is released, there is nothing for sperm to fertilize, and so you cannot get pregnant.

Most birth control pills contain synthetic (man made) forms of two female hormones: estrogen & progestin. These man made hormones stabilize a woman’s natural hormone levels and prevent estrogen from peaking mid-cycle. Without the monthly increase in estrogen, the pituitary gland is not triggered to release other hormones that would then cause the ovaries to release mature eggs. Thus, ovulation does not take place when you regularly take your daily birth control pills.

Synthetic estrogen in birth control pills works to:

(1) Stop the pituitary gland from producing follicle stimulating hormone (FSH) & luteinizing hormone (LH) in order to prevent ovulation
(2) Support the uterine lining (endometrium) to prevent breakthrough bleeding mid-cycle

Synthetic progestin in birth control pills works to:

(1) Stop the pituitary gland from producing luteinizing hormone (LH) in order to prevent egg release
(2) Make the uterine lining inhospitable to a fertilized egg (making birth control pills potentially abortifacient in the event that sperm successfully fertilized an egg)
(3) Partially limit the ability of sperm to fertilize the egg
(4) Thicken the cervical mucus to hinder sperm movement (although this effect may have little impact in preventing pregnancy from taking place)

In summary, birth control pills like Desogen use synthetic hormones to prevent ovulation and to thicken the cervical mucus — both of which help keep sperm away from an egg; in doing this, the birth control pills prevent pregnancy.

Technically speaking, there’s no need for menstruation if you’re on the pill. However, most birth control packs contain placebo pills (commonly sugar pills which lack any synthetic hormones) that trigger monthly bleeding similar to a period.

Here’s how a normal menstrual cycle works:

Normally, a woman’s menstrual cycle is regulated by the ebb and flow of several hormones. Each month, these hormones signal the uterus to grow an extra lining to possibly welcome a fertilized egg. If fertilization doesn’t occur, then the uterine lining, or endometrium, is shed as menstrual fluid. To a degree, your period is your body’s way of cleaning up the house in order to get ready for a possible pregnancy. The hormones in birth control pills prevent ovulation and also stop the uterine lining from growing.

Here’s why women taking birth control pills still appear to menstruate each month:

In 1958, two doctors named Gregory Pincus & John Rock modernized contraception with the first clinical trials of oral contraceptives. Pincus & Rock decided that the birth control pill would be more acceptable to women (and the Catholic Church) if the pill maintained women’s natural menstrual cycle. So, Pincus & Rock developed the birth control pill to replicate the typical 28-day menstrual cycle. Even today, most monthly birth control packets include 21 days worth of hormone pills and 7 days worth of sugar pills. By taking the placebo pills during the fourth week and cutting off the supply of synthetic hormones, bleeding is triggered within your body which is similar to menstruation. This bleeding, however, is not true menstruation, and it has nothing to do with whether an egg was ever released. Withdrawal bleeding tends to vary from typical periods by being lighter and usually shorter; this is because the uterine lining never thickened.

It’s believed that menstruation really serves no biological purpose when you are on birth control pills. It’s believed to be perfectly fine to skip the sugar pills and jump right into your next month’s hormonal pills when you reach day 22. In fact, manufacturers of birth control pills are finally catching on and letting women gain more control over when we experience our periods by providing larger packs of hormonal birth control pills with fewer placebo pills which let us have our periods only once every three months (or even less).