The size of a woman’s breasts is largely determined by genetics and there is a huge variation between women. Breast size can also be affected by weight loss or gain and women who are on the Pill may experience an increase in breast size. Pregnancy and breastfeeding will also cause an increase in breast size. It is normal for women to have some difference in size and shape between their two breasts.
It is a good idea for females to check their breasts regularly from the teenage years onwards. This helps them become familiar with the normal shape and look of their breast and the changes that occur during the menstrual cycle. However, if you are not comfortable with examining your breasts then this can be left to a health professional. See a doctor immediately if you notice any lumps, thickenings, skin changes, tenderness, nipple discharge or any other changes.