The cause of breast changes in early pregnancy is exactly the same as the cause of breast changes during your monthly cycle hormones. It is easy to assume that your tender breasts are a signal that your menstruation is about to start. Unfortunately, there is no formula to distinguish tender breasts before a period from tender breasts that are caused by early pregnancy. The only difference when you are pregnant is that your breasts will continue to feel sore, bigger, and more tender, and your period will not turn up. Breast changes are often one of the earliest symptoms of pregnancy.
Most women will notice a change in their breasts before their period was due, and will notice that their breasts will continue to go through changes during their whole pregnancies. As your due date draws nearer, and your body prepares itself for childbirth and breastfeeding, you are likely to start leaking colostrum, the first milk your baby gets, from your breasts. Colostrum production can start as early as 22 weeks gestation. Many women will see that their breasts increase in size as their pregnancy goes on. The size and color of your nipples may also change. Do not be alarmed by this it is totally normal. Breasts may also feel slightly lumpy during pregnancy and while breastfeeding. Tender breasts alone are not enough to make you conclude you are pregnant. If you are looking for a full list of symptoms, take a look at our pregnancy signs page. If you are still breastfeeding and wondering if you might be pregnant again, our article about early pregnancy symptoms while breastfeeding might be interesting to you.