Breast tissue is exposed to different hormone levels (oestrogen and progesterone) during menstruation, pregnancy, breastfeeding and menopause. This means that throughout life, but significantly during pregnancy and breastfeeding, your breast size and shape may change significantly. Many women fear that breastfeeding will make their breasts sag. But a study in 2007 showed that breastfeeding itself is not the culprit.

Factors that can change your breast appearance more than breastfeeding include:

  • Body mass index (BMI) a measure of your percentage of body fat
  • Number of pregnancies
  • Large pre-pregnancy breast size
  • Ageing
  • Smoking
  • Genetics
  • weight gain during pregnancy

Breastfeeding can however leave one breast looking different to the other. Breast tissue swells with milk and then shrinks again after breastfeeding, which can cause the contours of your bust to change

It's possible for one breast to return to its pre-pregnancy size after breastfeeding while the other stays larger, or droops, or flattens more. Some women end up with one breast a full cup size smaller or larger than the other after breastfeeding, which can be a cosmetic concern but is quite normal. Any dimpling or puckering of the breast, however, could be a sign of a breast lump underneath and should be evaluated by your doctor.