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What's With Those Pregnancy Hormones?

Updated: May 3, 2023

There are a lot of changes that take place during pregnancy, and hormones play a HUGE role in those changes.

Here are a few of the main players:

  • Estrogen

  • Progesterone

  • Relaxin

  • Oxytocin

  • Prolactin

Estrogen is probably the most well-known hormone, and it is very important throughout all the phases of woman’s life. However, during pregnancy you’re body is flooded with estrogen—increasing up to 30x the normal levels! Its main job during this time is to help stimulate uterine growth, but it will also increase blood flow to other parts of your body. Have you ever heard of anyone getting nose bleeds during pregnancy? Estrogen was probably to blame!

Progesterone is another very important hormone that works very hard during pregnancy--your ovaries go into overdrive during the first 7 weeks of pregnancy producing lots of progesterone. This hormone is super important for maintaining the endometrial layer that your growing baby will be attach to, as well as helping to maintain a healthy pregnancy (low levels of progesterone put you at increased risk for a miscarriage). High levels of progesterone during pregnancy is one of the main causes of morning sickness.

Progesterone is very busy throughout your pregnancy also helping the body to store fat as baby’s growth progresses. Another one of its responsibilities is to prepare mom’s body for milk production so baby will have lots of yummy breastmilk upon arrival. High levels of progesterone help to relax the surface of the uterus, but this aspect of progesterone can also impact other parts of the body, like the lower esophagus, resulting in increased heartburn during pregnancy.

Speaking of relaxing…relaxin helps to inhibit or stop premature uterine activity and helps to soften the cervix. One of the most common myths about relaxin is that it is 100%responsible for relaxing all the ligaments in a pregnant body, but that is NOT entirely true. However, it does help to relax your joints, including the public symphysis to help get ready for baby’s delivery.

Oxytocin increases at the end of pregnancy and during labor. Because oxytocin stimulates uterine contractions, progesterone suppresses it during pregnancy, but it shows up for the big moment, and it will continue to work after baby is born to help uterus contract to expel the placenta. Oxytocin is sometimes used to induce labor or to help it progress—it is more commonly known by its brand name: Pitocin. Oxytocin also helps stimulate the milk-ejection reflex that is necessary for breastfeeding.

Breastfeeding is possible because of a feedback loop involving oxytocin and prolactin. Oxytocin allows milk to let down and then prolactin is responsible for milk production.

Prolactin will lead to enlargement of the mammary glands…as a result, each breast can increase by one pound each! That is one reason new moms may notice more back or neck pain.

Inspire Physical Therapyhelps women prepare for pregnancy, labor and delivery, and all stages of postpartum recovery. If you want or need help optimizing your musculoskeletal health, before, during, or after pregnancy, please give us a call—we would love to help!

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