Physiologic Changes in Pregnancy
During pregnancy, the size and weight of the breasts approximately double as glandular elements proliferate under hormonal stimulation. Both lobular and alveolar growth occur. The histology reflects preparation for lactation, with an excess of glandular elements over stroma (in contrast to "resting" breast tissue, where stroma predominates). Mammary blood flow doubles. Small amounts of colostrum are produced prior to delivery. After delivery, placental and ovarian hormonal inhibition of lactation is released, and prolactin stimulates galactopoiesis. The mechanical stimulus of suckling allows lactation to continue virtually indefinitely. When nursing is stopped, milk stagnates and lactation ceases within 48 hours. Involution of the breasts follows.[2]
Comments