The breasts change and grow in size. The areola changes color and gets darker. Moreover, it gets more sensitive and larger as well. The reason behind this growth is acinus. Acinus grows in size in preparation for lactation after the baby is born and is located right at the tip of the breast duct.
The breasts grow up to three to four times heavier than normal. Normal breasts weigh around 200g but after pregnancy, they can grow up to 600 to 800g.