Progesterone in pregnancy: normal values, what it is and when to take it

In this article we will see how it is produced, what it is for and what the normal values ​​of progesterone are during pregnancy. Finally we will see the use of progesterone as a therapy in cases of threatened abortion and preterm birth.

What is progesterone and what is it for during pregnancy

Progesterone is sometimes referred to as P4 or Prog is a hormone created in early pregnancy by a gland called the corpus luteum . This gland continues to produce progesterone for 10 weeks during pregnancy. After those initial weeks, the placenta takes over producing progesterone. During the first trimester, progesterone levels rise exponentially, but stabilize shortly thereafter. 

Progesterone has a key function:

  • in the correct development of the various phases of the menstrual cycle;
  • in initiating and maintaining a pregnancy.

In particular, during pregnancy progesterone helps the uterus to grow and prevents it from having contractions which otherwise, during the first part of pregnancy, could lead to a miscarriage. In late pregnancy, progesterone helps the breasts prepare to produce breast milk. It also helps your lungs work harder to give oxygen to your growing baby.

Treatment with progesterone during pregnancy can help reduce the risk of preterm birth (ie, a delivery before week 37).

During fertility treatments such as in vitro fertilization, progesterone is often given because the drugs used in this therapy reduce the woman’s natural production of the hormone.

The progesterone levels given below are averages. Actual values ​​can be influenced by many different factors, such as:

  • the phase of the cycle (whether ovulation has occurred or not);
  • the laboratory that performed the measurement;
  • the time of day in which the sample was taken (near or away from meals; morning or afternoon).

With these premises, here are some average reference values.

  • women at the beginning of the menstrual cycle: 1 ng/mL or less;
  • women before ovulation: blood progesterone values ​​remain below 10 ng/ml;
  • Women, midway through the second phase of the cycle: Approximately 7-10 days after ovulation, progesterone levels remain above 8-10 ng/mL;
  • mid-cycle women: 5 – 20 ng/mL;
  • first trimester of pregnancy : 11.2 – 90 ng/mL;
  • second trimester of pregnancy: 25.6 – 89.4 ng/mL;
  • third trimester of pregnancy: 48.4 – 42.5 ng/mL.

Progesterone levels are usually highest when pregnant, but can reach values ​​as high as 20 ng/mL, even in a non-pregnant woman.

Normal levels of progesterone during pregnancy

During a pregnancy, to increase the probability of a successful outcome, progesterone levels should be kept above the threshold of 10-12 ng/mL

High progesterone levels

The two most common reasons for an elevated progesterone level in the blood are ovulation and pregnancy. Otherwise, the occasions – rarer – in which the levels of this hormone can rise are given by,

  • a laboratory error due to nonspecific reaction with other hormones;
  • taking progesterone supplements;
  • ovarian cancer;
  • adrenal cancer;
  • a congenital adrenal hyperplasia, a group of disorders affecting the adrenal glands.

The function of progesterone

Progesterone prepares the endometrium, ie the inner lining of the uterus, for the implantation of the fertilized egg and therefore also for a possible pregnancy. Progesterone prevents contractions of the uterus from occurring, and prevents the maturation of a new follicle from occurring.

Progesterone and ovulation

Usually, progesterone levels are measured about a week after you think you ovulate, as they should be at their highest at this time.

If blood is drawn too early, the test may give a false negative result . A false negative means that ovulation has occurred, but blood was taken too early, and therefore progesterone levels had not yet risen.

After ovulation, progesterone is produced in increasing amounts by the corpus luteum, rising on the first day after ovulation from a baseline of 1.5 ng/mL, up to 3 ng/mL. Its levels continue to rise until they reach – after 7 days – a peak of up to 10-20 ng/mL.

Progesterone levels can vary, even during the same day, depending on when blood is drawn.

Progesterone benefits

Estrogen, the primary female sex hormone, stimulates tissue growth within the uterus. To prevent the uterus from overgrowing, progesterone slows this activity and redirects the growth elsewhere. Your doctor may put you on progesterone to reduce the risk of miscarriage and to maintain proper progesterone levels during pregnancy.

Other benefits include:

  • Stimulates bone growth, helping protect against osteoporosis.
  • Helps maintain a healthy weight by burning body fat for energy.
  • It decreases the desire for sweet and sugary foods, stabilizing blood sugar levels.
  • It is a diuretic, normalizes body fluids and salt levels.

How to take progesterone

Progesterone can be given:

  • orally, in the form of tablets
  • for topical use, in the form of a cream
  • in the form of vaginal ovules
  • with intramuscular injections
  • in the form of a solution.

Side effects of progesterone during pregnancy

Common side effects when using progesterone:

  • Drowsiness
  • Fluid retention or swelling
  • Hot flashes
  • Depression
  • Vaginal discharge.
  • Urinary problems
  • Dizziness
  • Abdominal pain or cramps
  • Heachache
  • Breast tenderness
  • Articolar pains

Maintain the right hormonal balance naturally

Here are some natural remedies to help maintain the right hormonal balance.

Maintain a normal weight

Estrogen and progesterone balance each other in the body. If body fat increases, the estrogen level can rise, as fat cells can convert other hormones into estrogen. Maintaining a normal weight helps keep estrogen balanced, indirectly contributing to progesterone control.

Avoid getting too much exercise and stress

Stress leads to a sustained and elevated production of cortisol (the most important stress-related hormone). Since our bodies are not made to produce cortisol at such high rates, at a certain point they fold by transforming the available progesterone into cortisol. This compensation helps you survive, but leaves your ovarian hormones out of balance.

Ask your doctor about a possible intake of chaste tree

Chasteberry is  an herb known to improve progesterone production. Specifically, it works by stimulating the pituitary gland to produce more luteinizing hormone, which in turn signals the ovary to produce more progesterone.


Progesterone is a hormone released by the corpus luteum in the ovary. Progesterone in pregnancy plays important roles in the menstrual cycle and in maintaining the early stages of gestation: it helps the uterus to grow and prevents it from contracting otherwise ; helps the breast prepare to produce breast milk; it helps the lungs work harder to give oxygen to your growing baby. Treatment with progesterone during pregnancy can help reduce the risk of preterm delivery. During fertility treatments such as in vitro fertilization, progesterone is often given because the drugs used in this therapy reduce the woman’s natural production of the hormone.

Katherine Johnson, M.D., is a board-certified obstetrician-gynecologist with clinical expertise in general obstetrics and gynecology, family planning, women’s health, and gynecology.

She is affiliated with the Obstetrics and Gynecology division at an undisclosed healthcare institution and the online platform,

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