What Does Progesterone Do In Pregnancy?

Progesterone is a hormone that is essential for pregnancy. It is produced by the ovaries, the placenta, and the adrenal glandsProgesterone levels rise throughout pregnancy and play an important role in preparing the uterus for pregnancy, preventing miscarriage, and supporting the growth of the placenta. Here’s a closer look at what progesterone does in pregnancy.

Prepares the Uterus for Pregnancy

Progesterone thickens the lining of the uterus, making it a more hospitable environment for the fertilized egg to implant. This is important because if the lining of the uterus is not thick enough, the fertilized egg may not be able to implant properly, which can lead to pregnancy complications.

Prevents Miscarriage

Progesterone helps to keep the uterus relaxed, which prevents contractions that could lead to miscarriage. This is especially important during the first trimester of pregnancy when the risk of miscarriage is highest.

Supports the Growth of the Placenta

The placenta is the organ that connects the mother to the baby and provides the baby with oxygen and nutrients. Progesterone helps to keep the placenta healthy and functioning properly. This is important because if the placenta is not functioning properly, the baby may not receive the nutrients and oxygen it needs to grow and develop properly.

Promotes Breast Development

Progesterone helps to prepare the breasts for breastfeeding. It promotes the growth of milk-producing glands in the breasts and helps to increase blood flow to the breasts.

Prevents Preterm Labor

Progesterone helps to keep the uterus relaxed, which prevents contractions that could lead to preterm labor. This is important because preterm labor can lead to complications for both the mother and the baby.

Progesterone Supplements

In some cases, women may need to take progesterone supplements during pregnancy. This is often the case for women who have a history of miscarriage or preterm labor. Progesterone supplements can help to reduce the risk of these complications.

Progesterone Levels During Pregnancy

Progesterone levels typically rise throughout pregnancy, reaching their peak in the second trimester. After the baby is born, progesterone levels drop, which triggers the onset of labor and delivery.

Progesterone: The Pregnancy Hormone

Given its role in assisting a woman in becoming pregnant and maintaining her pregnancy, progesterone is sometimes referred to as the “pregnancy hormone.” The uterus prepares itself with progesterone to receive and maintain a fertilized egg.

During the first few days of a woman’s menstrual period, her progesterone level is typically low.

But after she ovulates, her progesterone level rises for approximately five days before falling.

Progesterone and Hormone Therapy or Hormone Replacement Therapy

In women who have undergone menopause but have not undergone a hysterectomy (the surgical removal of the uterus), progesterone is occasionally administered as a component of hormone replacement therapy (HRT). (4).

In order to treat menopausal symptoms and lower the risk of contracting specific diseases, hormone therapy (HT) typically involves taking estrogen.

Be aware that progesterone side effects can include the following:

  • Headaches
  • Breast tenderness or pain
  • Vomiting
  • Diarrhea
  • Constipation
  • Tiredness
  • Mood swings
  • Irritability
  • Sneezing
  • Coughing
  • Vaginal discharge

Progesterone use can also result in more severe side effects, including the following:

  • Breast lumps
  • Migraines
  • Dizziness and faintness
  • Impaired speech
  • Seizures
  • Numbness in the arms or legs
  • Swelling or pain in the legs
  • Balance issues
  • Difficulty breathing
  • Accelerated heartbeat
  • Chest pain
  • Vision issues
  • Uncontrollable shaking in the hands
  • Stomachaches
  • Itchy skin or rash
  • Vaginal bleeding
  • Depression

Call your physician if you experience any of these severe side effects.

Fertility Problems and Progesterone Tests

Your doctor might advise a progesterone blood test if you’re having trouble conceiving to determine whether you’re ovulating and whether your ovaries are healthy.

Your doctor might advise a blood test to see if your pregnancy is at risk for complications like miscarriage or preterm delivery if your progesterone level is low but you are pregnant. (2).

The following are warning signs and symptoms that you may have low progesterone levels: (1)

  • Uterine bleeding
  • Missing your periods or having abnormal periods
  • Spotting and pain while pregnant
  • Repeated miscarriages

You can have too much estrogen if you don’t have enough progesterone. Your sexual desire may decline, you may gain weight, and your gallbladder may be affected by a high estrogen level.

What is the link between progesterone and a healthy pregnancy?


Progesterone is a hormone that plays an important role in pregnancy. It prepares the uterus for pregnancy, prevents miscarriage, supports the growth of the placenta, promotes breast development, and prevents preterm labor. Progesterone levels rise throughout pregnancy and peak in the second trimester. Women who have a history of miscarriage or preterm labor may need to take progesterone supplements during pregnancy. If you are pregnant and have any questions about progesterone, be sure to talk to your doctor. They can help you understand the role of progesterone in pregnancy and determine if you need to take progesterone supplements.

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