After pregnancy, HCG increases rapidly in the early stages and estrogen and progesterone fluctuate significantly. In addition, if a woman has breast enlargement, she may also experience a more pronounced swelling and pain after pregnancy. In rare cases, a pregnant woman who happens to have breast cancer, or a benign tumor, may also experience breast swelling and pain. If the pain is particularly pronounced, or if there are significant localized folds in the breast with an orange peel appearance, prompt medical examination is indicated.