Description
During pregnancy the breasts increase significantly in size, increasing by about 400grams per breast, under the influence of estrogen progesterone growth hormone insulin and cortisol. Prolactin also plays a role in breast enlargement during pregnancy resulting in an overall average increase in size of about 145mls. The higher levels of estrogen result in progressive proliferation, elongation, and dilatation of the ductal system while progesterone is mostly responsible for glandular development. Most of the fat of the breast is replaced in late pregnancy by enlarging glandular tissue necessary to produce milk. The nipple and areola become deeply pigmented and increase in size as well.