Progesterone 101

Few things are more complex than a woman’s hormones just before and during pregnancy. It’s a time of intense fluctuation, requiring levels to be just right in order to achieve and sustain the rapid growth of a fetus. Even with all the other pieces in place, healthy hormone levels create the balance necessary for gestational carriers to have a successful surrogacy outcome.

What does progesterone do?

Often referred to as "the pregnancy hormone,” progesterone is a natural female hormone that is required in proper levels for a healthy reproductive system.

So exactly what does progesterone do during pregnancy?

According to The National Infertility Association, it serves several key functions:

Before pregnancy: Progesterone prepares the uterus. The ovaries begin producing progesterone after ovulation to thicken the uterine lining – ultimately creating a healthy, supportive space for the embryo to grow.

During early pregnancy: Progesterone remains important to ensure a healthy environment for the growing fetus. By about week 8 of the pregnancy, the placenta is developed enough to take over progesterone production.

Progesterone in early pregnancy

In the first trimester especially, healthy progesterone levels are key to an ongoing pregnancy. Some might even go so far as to say that progesterone can save a pregnancy: a 2017 study showed that two-thirds of women who used a hormonal progesterone supplement prior to pregnancy went on to deliver babies, regardless of having at least 2 prior miscarriages.

116 women who had lost at least two early pregnancies had their nCyclinE levels tested to provide a molecular marker for endometrial health. If she had an abnormal level, she was then prescribed a vaginal progesterone supplement to be taken twice a day during the second half of her menstrual cycle.

According to the study, the intervention worked: 68% of the women in the progesterone group ultimately went on to have successful pregnancies, while only 51% of the women who did not receive the hormone had the same outcome.

Progesterone in IVF

During IVF, or In Vitro Fertilization, the body needs support in supplying some of these key hormones. In order to increase progesterone to get pregnant and to prepare for the IVF procedure, surrogates take fertility drugs or hormones so that the reproductive organs are ready for conception.

One surrogate medication taken pre-embryo transfer is progesterone – also called by various brand names including prometrium or endometrin – which can be delivered in a variety of different forms:

• Vaginal gels
• Vaginal suppositories or inserts
• Oral capsules taken vaginally
• Intramuscular injections

This is to prepare the uterine lining for implantation of the embryo and continued after transfer for the maintenance of the early pregnancy. If progesterone levels are too low, the surrogate may experience spotting or ultimately a miscarriage. Low levels of progesterone can also be a sign of an ectopic pregnancy, so regular lab work helps monitor this.

Once the pregnancy is confirmed, usually at about 8 to 10 weeks, and the body is capable of producing progesterone on its own, the use is discontinued.

Ultimately, any woman who is planning to become pregnant needs a healthy amount of progesterone. These levels often need a boost both before and during the early stages of pregnancy, particularly in a gestational surrogate or even a traditional IVF cycle. Your reproductive endocrinologist or obstetrician can help you determine your individual needs.

If you’re in the early stages and need information about surrogacy medication, we are here to help support you through every step of the process.