"I am eight months
pregnant and my breasts have begun leaking. The doctor has told me that this is
normal at the end of pregnancy and that the substance is called colostrum. What
is colostrum and is this the same as the milk that I'll be feeding my new baby?"
The hormone changes of pregnancy stimulate
development of the breast tissue beginning in the first trimester. As early as
the second trimester the hormone prolactin stimulates milk producing cells
to produce colostrum a thin white to yellow colored fluid. Colostrum
contains lactose (milk sugar), protein, lactoferrin, and antibodies important for
fighting and preventing infections.
After delivery of the placenta the
progesterone levels in the mother's blood drops causing an increase in the
production of milk. During the first three to five days after delivery the composition of
milk begins to change with increased levels of α-lactalbumin, lactose,
citrate, glucose, free phosphate, and calcium, and decreased levels of
lactoferrin and antibodies. This transition to mature milk takes about two
1.Eglash A, Montgomery A, Wood J. Breastfeeding. Dis Mon. 2008 ;54:343-411.PMID:18489970
Reviewed: Mark Curran, M.D.