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Pregnancy Hormones

Lori Ramsey


When conception occurs, the body begins a remarkable change. Much of these changes occur over the duration of nine months. Hormones are the main catalyst for the changes. The hormones are like little chemical messengers that run the show during pregnancy. In fact, hormones are what make, grow and finish a pregnancy. Fluctuations in these can cause an array of symptoms. Understanding them, helps to prepare for what may come during the nine months.

The levels of human chorionic gonadotropin (hCG), estrogen and progesterone will increase as the pregnancy progresses. This increase will set about some major changes in the body. The uterus and abdomen muscles will have to expand to take on the growing fetus and the breast changes to nourish the baby after his arrival.

Among the first changes you may notice during pregnancy are with your breasts. They will enlarge as the milk-producing glands increase in size. It's the rising levels of both estrogen and progesterone that is responsible for the enlarging breasts.

During early pregnancy the corpus luteum (the cyst that was formed when the egg burst forth from the ovary) will produce the minute amounts of progesterone that will keep the uterine lining from shedding. Weeks later, the placenta will take over the production of progesterone that maintains the pregnancy. Progesterone levels are ten times higher in a pregnant woman than in a non-pregnant woman. Progesterone is responsible for keeping the uterine lining from shedding, thus preventing miscarriages. Low levels of progesterone can cause miscarriages, and later on can cause preterm labor or premature birth. Progesterone keeps the uterus from contracting and promotes the growth of blood vessels in the walls of the uterus, which is essential for the baby's nourishment.

Estrogen is also produced by the placenta as well as small amounts coming from the ovaries. Estrogen is considered the pregnancy hormone. It's the key hormone is conception, causing the egg to burst forth from the ovary, and causing changes in the cervix, vagina, breasts and uterus to help bring about fertilization. Estrogen also influences the production of insulin.

hCG is produced by the placenta in small amounts at first, increasing as the pregnancy progresses. hCG is the hormone that pregnancy tests detect. It can be detected in both urine and blood specimens. It's the hCG that keeps your body from rejecting the growing baby. If they levels start to fall off early in the pregnancy, this could be a warning sign of a miscarriage.

During pregnancy the levels of estrogen and progesterone are suppose to rise to maintain the pregnancy in a normal way. Levels that fluctuate will cause an array of problems, from miscarriage, preterm labor, gestational diabetes, to premature birth. The levels rise and peak out right before birth, then they drastically drop. It's this drop that causes post partum depression, night sweats and mood swings.

Lori Ramsey is a contributing writer for Baby Corner. Visit her sites at and .

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