Immediately after conception, the body begins to prepare for breastfeeding, and the milk duct system in your breasts becomes fully developed sometime during your second trimester of pregnancy. (breastmilk.com)
Just to see if I can't squeeze anything, and alas, breastfeeding during the second trimester makes for hard work. (simplymombailey.com)
This is a normal part of pregnancy, especially during the second trimester. (tinyfry.com)