Can your breast change after having sex for the first time
Nope! Having sex won’t change the shape or size of any part of your body in any way (unless pregnancy happens).
Puberty is what causes your body to change as you grow into an adult. For girls, this includes breasts growing and changing shape. Puberty can last up to age 20, and it happens in stages. If you’re having sex while you’re going through puberty, it may seem like sex is causing changes in your breasts, but it’s not.
While sex won’t change your breasts, hormonal birth control can cause breast changes for some people. Pregnancy can also cause breast changes. If you’ve had unprotected sex and missed a period, take a pregnancy test. Otherwise, you don’t have to worry about sex changing your breasts or body.
-Kendall at Planned Parenthood