Pregnancy Hormones

Estrogen, hCG, prolactin and other pregnancy hormones

When you become pregnant, your body produces a number of different hormones, each of which plays a specific role. While these hormones are at least partially to blame for some of the side effects of pregnancy, like unusual food cravings, morning sickness and mood swings, they also contribute significantly to the health of your developing baby and are a very important part of every pregnancy.

One of the best-known pregnancy hormones is hCG or human chorionic gonadotropin. Because hCG levels in early pregnancy are high, it is the chemical that both clinical and home pregnancy tests look for. However, as you will see, your hCG levels are only one part of the equation.

Hormones You Should Know About

  • hCG: Human chorionic gonadotropin is produced as the result of the fertilized egg implanting in your placenta. Its levels are highest in early pregnancy and usually begin to subside by the second trimester of pregnancy...which is right around the time when you'll likely notice your bouts of morning sickness becoming less and less intense.
  • hPL: A related chemical called human placental lactogen, abbreviated as hPL, prepares your metabolism for the rigors of pregnancy and prepares your breasts for lactation and breastfeeding.
  • Estrogen: Produced by your ovaries and your placenta, estrogen is the central hormone in pregnancy. It plays a very important stimulating role, prompting uterine growth, breast enlargement, milk production and increasing blood flow throughout your reproductive system to aid in the delivery of nutrients.
  • Progesterone: Rising progesterone levels during pregnancy help keep the fluid flowing through your placenta and strengthen your uterine wall, though this hormone is also fingered as the culprit for some physical discomforts that often occur during pregnancy, such as constipation, heartburn and indigestion.
  • Relaxin: The function of this hormone is to soften the ligaments in your pelvis and other joints, making your pelvis more flexible in order for your baby to pass through more easily at birth. This loosening of the joints is partially responsible for the extra aches you experience during pregnancy, especially back pain.
  • Oxytocin: This hormone triggers the muscle contractions that signal the arrival of labor. It can be administered artificially if inducing labor is something you choose or need to do.
  • Prolactin: This hormone stimulates your milk production and is believed to have a calming effect on nursing mothers. Though it is said to stimulate hair growth all over your body, you can expect this hair growth to be temporary; it usually subsides after three to six months.