What’s the Role of Progesterone in Pregnancy and Infertility Treatment?

Progesterone is a hormone that plays an important role in becoming and staying pregnant. It’s often prescribed as part of infertility treatment or if you’ve had issues with past pregnancies. But what does progesterone actually do during pregnancy? And will taking it increase your chances of becoming pregnant?

What’s the role of progesterone during pregnancy?

Progesterone is a natural hormone that plays several roles when it comes to pregnancy. 

Progesterone helps you become pregnant by changing the lining of the uterus. This makes it possible for a fertilized egg to attach to it and start growing into an embryo. Progesterone levels start to increase during ovulation to prepare the uterus for a fertilized egg. 

Once you become pregnant, progesterone helps support pregnancy in several ways:

• It helps prevent your immune system from attacking the developing embryo.

• It prevents early contractions by relaxing the muscles in the uterus.

• It helps control blood pressure by widening your blood vessels.

• It helps support the development of the brain and spinal cord in the embryo. 

Each menstrual cycle, the ovaries make progesterone after an egg is released. If that egg gets fertilized and then implants, the ovaries keep making progesterone to support the pregnancy. But after about 7 weeks, the placenta takes over and makes progesterone for the rest of the pregnancy.

Disclosure

Progesterone

Avg retail price

$74.69(Save 78.98%)

GoodRx discount

$15.70

See all discounts

How it works

Use GoodRx to find medications, pharmacies, and discounts.

GoodRx discounts can help you pay less for your prescription.

Bring your free coupon or savings card to the pharmacy.

Progesterone levels during pregnancy

Progesterone levels naturally rise throughout pregnancy. The chart below shows common ranges of progesterone levels during pregnancy:

Low progesterone levels are associated with an increased risk of miscarriage. But there isn’t a set progesterone level that determines your risk. Progesterone levels change throughout the day. And your progesterone level may be very different from someone else’s. In most cases, your healthcare provider will look for progesterone levels that are increasing over time while you’re pregnant.

Is there a way to tell if you have low progesterone?

It’s very difficult to find out if a person has low progesterone. There’s no single test that can diagnose low progesterone levels. Blood tests for progesterone usually aren’t helpful because progesterone levels naturally change throughout the day. And other tests, such as an endometrial biopsy, are invasive, painful, and don’t always give a clear answer. Plus, low progesterone doesn’t always lead to miscarriage or preterm labor.

The most common symptom of low progesterone levels in non-pregnant women is irregular periods. Vaginal bleeding or stomach pain can be signs of low progesterone levels during early pregnancy. But there are other things that can also cause these symptoms.

Since it’s difficult to know if low progesterone levels are contributing to pregnancy issues, your provider may recommend progesterone treatment based on your medical history instead of your symptoms or progesterone levels. More on that next.

Who needs treatment with progesterone during pregnancy?

Sometimes, your body may not make enough progesterone on its own. As mentioned, it can be difficult to test for this, so progesterone treatment is often recommended for the following reasons to help support a healthy pregnancy:

• As part of infertility treatment: Progesterone is an important part of many treatments to improve fertility, including in vitro fertilization (IVF). Multiple studies show that taking progesterone improves the chance of becoming and staying pregnant through assisted reproductive technology (ART).

• To prevent early pregnancy loss: Unfortunately, some pregnancies end in a miscarriage in the first trimester. It can be difficult to figure out the cause of early pregnancy loss, and genetic factors are often to blame. But as mentioned, low progesterone levels may also play a role. So if you’re pregnant and have a history of miscarriages, treatment with progesterone may be recommended to help prevent early pregnancy loss. 

• To prevent preterm birth: Babies born before 37 weeks of pregnancy are considered preterm (preemie). If you’ve had a premature baby before and you’re pregnant again, your healthcare team may recommend progesterone treatment. Many expert organizations recommend progesterone if you’re at risk for a premature delivery.

Does taking progesterone increase your chances of getting pregnant?

Possibly. If you have a history of early pregnancy loss, infertility, or irregular periods, taking progesterone may increase your chances of a successful pregnancy as part of your overall care plan. But if you have normal menstrual cycles and aren’t receiving infertility treatment, there’s no evidence that progesterone will increase your chances of becoming pregnant.

You should only take progesterone if your healthcare provider recommends it. If you have concerns about your progesterone levels or your fertility, your provider can do a full workup to determine the best treatment options for your needs.

How do you take progesterone during pregnancy?

Progesterone can be given orally, vaginally, or injected into a muscle.

Oral progesterone (Prometrium) capsules are less effective than other forms of progesterone when it comes to supporting pregnancy, so they aren’t prescribed as often. But oral progesterone capsules can also be inserted vaginally. So make sure you understand exactly how your provider wants you to use the capsules if they’re prescribed for you.

Vaginal progesterone comes in three main forms:

• Crinone, a vaginal gel that’s inserted once or twice a day

• Endometrin, a vaginal tablet that’s inserted two to three times a day

• Progesterone suppositories that may need to be made by a compounding pharmacy

All vaginal progesterone (including oral capsules inserted vaginally) can cause vaginal leakage and irritation.

Injectable progesterone, also called progesterone in oil, is used off-label for infertility treatment. It’s injected into a muscle, most often the upper outer portion of your butt muscle, which can be painful. 

Both vaginal and injectable progesterone are effective for increasing progesterone levels and therefore the chance of a successful pregnancy. Many people prefer vaginal progesterone over painful progesterone injections, but vaginal progesterone isn’t always an option. For example, there’s some evidence that progesterone injections may lead to more successful births after a frozen embryo transfer. But more studies are needed to confirm this. 

Your provider will work with you to decide what form of progesterone works best for your needs and lifestyle.

When should you start taking progesterone for pregnancy?

You’ll typically start taking progesterone around the time of ovulation (release of an egg from an ovary). In an IVF cycle, you’ll usually start progesterone within 3 days of egg retrieval. And if you’re having a frozen embryo transfer, you’ll typically start progesterone 2 to 5 days before the transfer date, depending on the stage of the frozen embryo.

Your provider will let you know when to start progesterone treatment based on your individual situation. Be sure to follow their instructions carefully — progesterone timing can be crucial to the success of some ART treatments.

Good to know: If you’re taking progesterone to help prevent preterm birth, you’ll typically start treatment when you’re 16 to 24 weeks pregnant.

How long do you need to take progesterone?

There’s no set time for how long you’ll need progesterone treatment once you become pregnant. In most cases, progesterone treatment continues until you reach 10 to 12 weeks of pregnancy. But in some cases, your provider may have you stop treatment as soon as you have a blood test that confirms you’re pregnant. And in others, you may continue progesterone treatment until you give birth. 

If you’re taking progesterone to help prevent preterm birth, you’ll continue treatment until you reach 36 to 37 weeks of pregnancy or you give birth.

What are the side effects of progesterone?

Common progesterone side effects include:

• Sore breasts

• Nausea

• Mood changes

• Weight changes

• Swelling or puffiness

These are also common symptoms of pregnancy, so it may be hard to know if your symptoms are being caused by progesterone alone.

Vaginal progesterone can cause vaginal discharge or irritation. And progesterone injections can cause pain, swelling, or redness at the injection site. 

It’s rare, but some people may have a mild allergic reaction to the sesame oil the progesterone is dissolved in. If this happens, your healthcare provider can recommend progesterone dissolved in a different type of oil, such as olive oil or ethyl oleate. But you’ll need to have this made at a compounding pharmacy.

If any progesterone side effects are bothersome, talk to your healthcare provider. They may recommend a different type of progesterone. Or they can give you tips to help manage the side effects you’re experiencing.

Is it safe to take progesterone during pregnancy?

Yes, it’s safe to take progesterone during pregnancy as long as your provider OKs it. There’s no evidence that progesterone harms your baby. In fact, it can help keep your baby safe since progesterone can prevent preterm birth. 

How to save on progesterone

There are many ways to save on your progesterone prescription. GoodRx can help you navigate your options, which may include GoodRx discounts, copay savings cards, and patient assistance programs.

• Crinone (vaginal progesterone gel): If you have commercial insurance, you may be eligible to pay as little as $15 for Crinone using a savings card from the manufacturer. If you’re uninsured or underinsured, you may be eligible for Crinone’s patient assistance program, which offers the medication free of cost.  

• Progesterone injection: GoodRx can help you save over 80% off the average retail price of injectable progesterone. Progesterone in oil’s price at certain pharmacies is as low as $31.05 with a free GoodRx discount.

• Progesterone capsules: GoodRx can help you save over 90% off the average retail price of progesterone capsules. The price of progesterone capsules at certain pharmacies is as low as $14.10 with a free GoodRx discount.

Why trust our experts?

Written by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

Reviewed by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

Our editorial standards

Meet our experts