The hormones in the pill stop you from ovulating, which is what makes them effective birth control methods. If there is no egg released, there is nothing for sperm to fertilize and, therefore, no pregnancy.
The key to stopping ovulation with birth control pills is proper use. Understanding how each type of pill works can help you get a better understanding of your fertility.
This article discusses how different types of birth control pills affect ovulation.
How Birth Control Affects Ovulation
Ovulation occurs when one of your ovaries releases an egg. When ovulation happens, the egg can be fertilized by a sperm and pregnancy can occur.
If you aren’t using hormonal birth control, ovulation usually happens mid-cycle, or around 14 days before your menstrual period.
Sperm can live for three to five days in a woman’s reproductive organs and an egg lives for just 12 to 24 hours after ovulation. So you are most likely to get pregnant if you have sex in the two to three days before or on the day of ovulation.
If you are using hormonal birth control, that changes things. Generally speaking, hormonal birth control sends messages to your brain saying you’ve already ovulated. This stops ovulation from occurring. How this works depends on the method of birth control you are using.
Combination Birth Control Pills and Ovulation
Combination birth control pills contain both estrogen and progestin, a synthetic form of progesterone. They prevent ovulation by tricking your brain into thinking you’ve already ovulated.
During a natural menstrual cycle, when you’re not using hormonal birth control, levels of the hormones estrogen and progesterone rise and fall. These hormones communicate with the pituitary gland, which controls ovulation.
If you use combination birth control pills, the hormone levels remain fairly steady throughout your cycle. This tells the pituitary gland that ovulation is not necessary.
Progestin-Only Birth Control Pills and Ovulation
The hormone in the progestin-only birth control pill, or mini-pill, sometimes stops ovulation. The main way it prevents pregnancy is by thickening the mucus in the cervix. This prevents sperm from reaching an egg, even if you have ovulated.
When You Might Ovulate on the Pill
If you do not take your birth control pill every day at the same time, there may not be enough hormones in your body and ovulation may occur. The risk for ovulation increases if you miss more than one pill in a row.
As mentioned, ovulation is possible if using the mini-pill, but the egg will not become fertilized with proper pill use.
Summary
Combination birth control pills that contain estrogen and progestin keep your body from ovulating. Since there’s no egg for the sperm to fertilize, it prevents pregnancy.
The combination birth control pill keeps hormone levels steady in your body to send a message to your brain that you’ve already ovulated.
Progestin-only birth control pills may stop ovulation. However, the main way it prevents pregnancy is by thickening mucus in the cervix to keep sperm from reaching the egg.
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