This week birth control pills have been in the news because there was a problem with a certain batch from Pfizer. I will give you information about the recall at the end of the article. Before I do I have a question for you.
Have you ever wondered how birth control pills work in the body?
Every year when I teach about female reproductive system I usually have at least one student ask how the process works. I thought I would take a few minutes to explain how birth control pills work to help understand why Pfizer had to recall Lo/Ovral®-28 and Norgestrel/Ethinyl Estradiol Tablets.
A women gets pregnant because she releases an egg from the ovary (this process is called ovulation) and it gets fertilized by sperm (this process is called fertilization) usually in the fallopian tubes or in the uterus.
In order to prevent pregnancy birth control pills are designed to prevent ovulation or fertilization. Both of these processes can be altered or stopped by using additional female hormones, estrogens or a combination of estrogen and progestins.
The estrogen is used to suppress ovulation. If the egg is never released from the ovary a woman will not get pregnant and she will have a period approximately two weeks later. The combination of estrogen and progestin pills also tries to suppress ovulation as well as alter the lining and mucus of the uterus.
The birth control pill thickens the cervical mucus in the uterus making it difficult for sperm to get into the uterus to fertilize an egg. The lining of the uterus is also affected so that a fertilized egg would not be able to implant and grow into a fetus in the uterus. The combination of these processes highly diminishes the likelihood of pregnancy.
Generally speaking, a woman will take active pills -- pills that contain female hormones for 21 days -- and then they will take inactive pills, pills that do not contain female hormones for 7 days. This keeps the cycle on a 28 day period.
Now that we have a general understanding of how birth control pills work in a woman’s body, let's understand why there was a need for a recall of several lots of birth control pills from Pfizer.