In early pregnancy, it owns the preparation of the endometrium for successful implantation and maintenance of the gestational sac in the uterus. It regulates the maternal immune system and enables the baby to start its development journey.

During fertility treatments such as IVF (in vitro fertilization), progesterone is often given because the medications used in the process tend to reduce the natural production of the hormone.

If you’re struggling to get pregnant, your doctor may recommend a blood test for progesterone to see if you’re ovulating or if your ovaries are healthy.

If your progesterone level is low during pregnancy, your doctor may recommend a blood test to monitor and avoid chances of miscarriage or preterm delivery. 

Signs and symptoms that indicate you may have a low progesterone level include the following: 

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

Also called P4 or Prog

Progesterone (also called P4 or Prog)  is a hormone produced early in pregnancy by a cyst on the ovary called the Corpus Luteum. This cyst of the ovarian follicles continues to produce progesterone for 10 weeks during pregnancy. After those initial weeks, then the placenta takes over producing progesterone. During the first trimester, progesterone levels rise exponentially, but plateau shortly after. Progesterone is key to creating a perfect environment for the ovaries to harbor the fetus by keeping the uterus muscle relaxed and helping the immune system tolerate foreign DNA. When a woman undergoes IVF or another fertility treatment, this hormone will sometimes need to be supplemented externally. Some women’s ovarian follicles might also be poorly developed and may not secrete enough progesterone on their own. In these circumstances, progesterone will need to be supplemented as well.

Role of progesterone pre-pregnancy

Just like lady’s maids get a lady ready for a nice family function, progesterone gets the uterus ready for accepting the baby.

It causes the luteal phase to start and transforms the endometrium (uterine lining) by thickening it to receive an embryo. The embryo is the result of the female’s egg when it’s fertilized by the male’s sperm. When pursuing pregnancy, the fertilized embryo will reach the uterus normally 5 days after ovulation. Then two days later, it will attach to the uterine wall. After it attaches to the uterine wall, this is when progesterone levels peak. If undergoing IVF, the client would normally go through progesterone supplementation to help encourage the fertilized embryo to attach to the uterine wall.

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Role of progesterone during pregnancy

When a woman is pregnant, she produces hCG (human chorionic gonadotropin hormone). This is a signal to the ovaries to continue to produce progesterone. hCG prevents the onset of her menses. Progesterone then continues to be produced, nurturing the foetus as it starts to grow. After 8-10 weeks of pregnancy, the placenta takes over progesterone production and increases production until the baby is born.

Benefits of Progesterone

Estrogen, the primary female sex hormone, stimulates the growth of tissue inside the uterus. But, it needs some help. To prevent the uterine lining from thickening too much, progesterone intervenes and redirects growth elsewhere. 

Progesterone causes an increase in blood flow to the womb. It might also be the one responsible for that pesky heartburn as well as vomiting, reflux, gas and constipation.

Later on, it helps with the baby’s development. It prevents the mum-to-be from producing milk until the baby is born and strengthens her pelvic floor muscles ready for labour.

In cases of fertility treatments, the doctor will give progesterone supplements to ensure that there is enough progesterone to help the estrogen do its work and thereby, prevent miscarriage.

Other benefits include:

• Stimulating bone growth, hence reducing risks of osteoporosis.
• Helping maintain a healthy weight by burning body fat for energy.
• Decreasing craving for sweet and high-sugar foods, stabilizing blood sugar levels.
• Since it is a diuretic, it aids in normalizing body fluid and salt levels.

What are normal progesterone ranges?

Progesterone is measured in nanograms per milliliter (ng/mL). It is measured by a regular blood test. Below are ranges that are considered normal: 

• 0.1 to 0.7 ng/mL in the follicular stage of the menstrual cycle

• 2 to 25 ng/mL in the luteal stage of the menstrual cycle

• 10 to 44 ng/mL during the first trimester of pregnancy

• 19.5 to 82.5 ng/mL during the second trimester of pregnancy

• 65 to 290 ng/mL during the third trimester of pregnancy

Some conditions can cause deviations from these ranges::

• Increased progesterone during pregnancy can mean that you have twins or an abnormal type of pregnancy called a molar pregnancy.

• Increased progesterone when you are not pregnant could mean you have a type of ovarian tumor called a lipid ovarian tumor, or chorionepithelioma.

• Decreased progesterone during pregnancy could mean that you have a risk for miscarriage (also known as spontaneous abortion).

• Decreased progesterone when you aren't pregnant could mean that you don't have enough female hormones, a condition called hypogonadism.

How can low progesterone affect pregnancy?

While studies are not very conclusive on this issue, doctors are wary of low progesterone levels since the uterine lining needs to be optimal for implantation.

Do progesterone supplements help prevent preterm birth?

If have a history of premature delivery, your doctor may talk to you about supplemental progesterone. Some studies have shown that getting weekly shots of progesterone starting at around 16 to 20 weeks of pregnancy and continuing through week 36 reduces the risk of preterm birth, although a more recent study did not show any benefits.

If you don't have a history of preterm birth and your doctor finds that your cervix has shortened to less than 2 centimeters when you're 16 to 24 weeks pregnant (which could flag risks of preterm birth), your doctor could prescribe a daily progesterone gel — it comes in a tampon-like applicator that you place in your vagina — or vaginal progesterone suppositories to be taken till 37 weeks of pregnancy.

Progesterone supplementation in these situations has been shown to effectively reduce the risk of preterm birth.

However, please don’t use progesterone supplements or creams on your own, without consulting your doctor since they may give you side effects and complications.