If you've every been pregnant or if you are pregnant
now, you've probably noticed a metamorphisis in your
bra cups. The physical changes (tender, swollen
breasts) may be one of the earliest clues that you
have conceived. Many experts believe that the color
change in the areola may also be helpful when it
comes to breast feeding.
What's going on
Perhaps what's even more remarkable than visible
changes is the extensive changes that are taking
place inside of your breasts. The developing
placenta stimulates the release of estrogen and
progesterone, which will in turn stimulate the
complex biological system that helps to make lactation
Before you get pregnant, a combination of supportive
tissue, milk glands, and fat make up the larger
portions of your breats. The fact is, your newly
swollen breasts have been preparing for your
pregnancy since you were in your mother's womb!
When you were born, your main milk ducts had already
formed. Your mammary glands stayed quiet until
you reached puberty, when a flood of the female
hormone estrogen caused them to grow and also to
swell. During pregnancy, those glands will kick
into high gear.
Before your baby arrives, glandular tissue has
replaced a majority of the fat cells and accounts
for your bigger than before breasts. Each breast
may actually get as much as 1 1/2 pounds heavier
Nestled among the fatty cells and glandular tissue
is an intricate network of channels or canals known
as the milk ducts. The pregnancy hormones will
cause these ducts to increase in both number and
size, with the ducts branching off into smaller
canals near the chest wall known as ductules.
At the end of each duct is a cluster of smaller
sacs known as alveoli. The cluster of alveoli is
known as a lobule, while a cluster of lobule is
known as a lobe. Each breast will contain around
15 - 20 lobes, with one milk duct for every lobe.
The milk is produced inside of the alveoli, which
is surrounded by tiny muscles that squeeze the
glands and help to push the milk out into the
ductules. Those ductules will lead to a bigger
duct that widens into a milk pool directly below
The milk pools will act as resevoirs that hold the
milk until your baby sucks it through the tiny
openings in your nipples.
Mother Nature is so smart that your milk duct
system will become fully developed around the time
of your second trimester, so you can properly
breast feed your baby even if he or she arrives
earlier than you are anticipating.