Using birth control can potentially increase the size of your breasts. The hormones in certain types of contraceptives might cause your breast tissue to grow. Those hormones can also cause fluid retention that results in your breasts feeling larger during certain points in your menstrual cycle. If you stop taking the pill, the effects you experienced when you started birth control will likely go away. Also remember that other factors might affect your breast size besides hormonal changes tied to your birth control.
Birth Control’s Hormonal Effects
Most types of hormonal birth control contain two hormones: estrogen and progestin (though some options, like the mini pill, contain only progestin). These hormones help prevent pregnancy by stopping ovulation and keeping the sperm from fertilizing the egg.
However, these hormones can also have other effects on the body. Estrogen and progestin are also responsible for the physical changes that take place during puberty, including developing wider hips and larger breasts. In addition, the type of fat found in the breasts contains a high level of estrogen receptors. When birth control introduces more estrogen and progestin to the body, it can cause your breasts to grow as the fat cells increase in size (but not in number).
Estrogen and progestin can also cause edema, which is more commonly known as fluid retention. This can create a bloated feeling accompanied by larger and fuller-feeling breasts. When you reach the placebo pill week of your birth control regimen, you might notice that your breasts feel smaller as the fluid retention decreases. This cycle repeats the following month when you start a new pack of pills with active hormones.
Some women believe changes in breast size while on birth control are due to weight gain. However, researchers have found no conclusive evidence that weight gain is a side effect of taking the birth control pill.
Which Types of Birth Control Affect Breast Size?
Any type of hormonal birth control can potentially cause your breasts to increase in size, including:
- Intrauterine devices (IUDs).
Note that this list includes forms of birth control with both estrogen and progestin as well as progestin-only options. However, each brand of birth control within these categories can have different amounts of hormones. If your hormonal birth control contains higher levels of estrogen and progestin, you might be more likely to experience physical changes to your breasts.
Types of birth control that don’t use hormones to prevent pregnancy won’t cause changes to your breast size. These include:
- Copper IUDs.
- Male condoms.
- Female condoms.
- Cervical caps.
How Long Will My Breasts Be Bigger?
The effects of birth control on breast size can vary from one person to the next. Some people experience a noticeable change in their breasts while others don’t notice any differences.
Often, a change in breast size is most noticeable when starting a new contraceptive. However, after a few cycles, these changes might dissipate. If not, you will likely see any increases in breast size due to fat cell growth or fluid retention wear off if you decide to stop using your hormonal birth control.
If you’d like to avoid developing bigger breasts when using contraceptives, you can consider nonhormonal options or talk to your Nurx™ medical provider about low-dose birth control. Because high doses of hormones generally increase the likelihood that your breasts will grow, a progestin-only pill or a combination birth control pill with no more than 20 micrograms (mcg) of estrogen might better fit your needs.
Other Possible Causes for Changes in Breast Size
If you notice a change in breast size while using birth control, it’s important to remember that it might not be related to the pill. A number of other factors could potentially cause your breasts to increase in size, including:
- Taking certain medications besides birth control, such as a type of antidepressant called a selective serotonin reuptake inhibitor.
- Hormonal imbalances.
- Your menstrual cycle (breasts can increase in size right before your period whether you’re on birth control or not).
- Weight gain.
- Pregnancy (breasts can start growing as early as one to two weeks after conception).
Although it’s unlikely that pregnancy is the cause of a change in breast size while you’re on birth control, it’s important to remember that the pill is only 99% effective even with perfect use. If you miss your period or have other signs of pregnancy in addition to bigger breasts, take an at-home pregnancy test or schedule a blood test with your healthcare provider to find out if that’s the cause.
If you have any issues with changes to your breasts while on birth control, talk to your medical provider. He or she can help you find a contraceptive you’re comfortable with and rule out other possible causes for an increase in breast size.