1. Breast swelling and pain. Immediately after implantation during pregnancy, the hormone levels in the body begin to change, which can lead to breast swelling and pain. At this time, the skin around the nipple and areola can also become sensitive. This reaction usually occurs early in pregnancy and lasts for several weeks. 2. Mild Abdominal Pain Immediately after implantation, the pregnancy begins to expand to accommodate the embryo. This can cause mild abdominal pain and discomfort