According to Ava Science, Inc., about a week before your period is due, your breasts or nipples could feel sore and tender. You may even notice they’re slightly crooked. Blame it on low estrogen.
Per Johns Hopkins Medicine, during the first half of your menstrual cycle, your breasts may feel hard and lumpy. This is because the milk glands in the breast enlarge to prepare for pregnancy.
At the end of your period, your breasts may decrease in size. Experts at Healthline suggested that due to estrogen and progesterone bottoming out, your boobs deflate and return to their normal size.
Estrogen levels start to surge in this phase to prepare the uterus for pregnancy. The increase causes the skin around your breasts to become more elastic, making them perkier and giving you a natural boost, according to SheCares.
Progesterone levels are at their highest towards the end of your cycle. As explained by Healthfully, the hormone causes water retention, making your breasts swell. Your boobs or nipples could also feel more firm, sore or tender