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Hormones During Pregnancy

A woman’s first pregnancy is one of the most exciting and dramatic events of her life. As conception progresses to implantation, and development of the pregnancy, numerous changes take place within the woman’s body. While a woman’s physical changes may be obvious, several other ones may be subtle, including a growing sense of emotional turmoil, associated with how a woman feels about being pregnant, the timing of the pregnancy, whether or not she is ready to start to grow her family, whether or not she is in a stable relationship with a partner, and or whether the pregnancy was planned or not. All of these issues and more are in the mix. But, to some degree, these changes are attributable to the hormones of pregnancy.

The first trimester of the pregnancy begins with conception. As egg and sperm unite, and the fertilized egg implants into the endometrium or uterine lining, a hormone called chorionic gondadotropin (HCG) is produced. HCG has a very predictable rise in the early weeks of pregnancy and peaks around 70 days. HCG is thought to support the pregnancy by ensuring ovarian production of progesterone until the placenta is well formed around the tenth week. HCG is thought to be the hormone responsible for a number of symptoms associated with early pregnancy, namely nausea and resultant vomiting and the sometimes overwhelming fatigue that can plague the early expectant woman.

Progesterone is one of the major hormones of pregnancy and is primarily produced by the placenta. Levels of progesterone in the body rise as the pregnancy progresses. Progesterone functions to inhibit the smooth muscle in the uterus from contracting and decreases prostaglandin formation, both of which allow the fetus to grow with the expanding uterus. As progesterone levels increases, other smooth muscle in the body may be affected, such as that in the lower esophageal sphincter, which results in increased heartburn and acid reflux, especially in the later stages of pregnancy. Progesterone softens cartilage as well and may be responsible for the commonly occurring hip and pubic bone pain that also occurs. This hormone also can cause tenderness in the breasts early on and the bloating feeling many women experience throughout pregnancy.

Estrogens also increase during pregnancy and are also produced primarily by the placenta. Among other functions, estrogen increases urine blood flow. Prolactin, the hormone that allows for lactation postpartum, also increases throughout pregnancy, and its production is thought to be stimulated by increasing levels of estrogens.

The rise in estrogen, as well as progesterone and other hormones in pregnancy, is also in part responsible for the magnification of emotions a pregnant woman experiences. Increased circulation levels intensify the myriad of feelings a pregnant woman has. Anxiety in regard to how a woman may feel about herself and the way her body is changing is normal, and her concerns regarding her own health and the health of the fetus are paramount. Anticipation of the new role of being a mother and the changes a new baby will bring to the family may be overwhelming. These emotions may be heightened throughout the pregnancy, and will return to normal once the hormones of pregnancy are gone.

After delivery or abortion, hormone levels decrease, and their fall may contribute to a short period of readjustment. Most women understand how these changing hormones of pregnancy have affected them, and recognize that it takes time to regain their balance.