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Progesterone and Pregnancy

Progesterone and pregnancy at a glance

  • Progesterone is a natural hormone vital for women before and during pregnancy.
  • Women produce progesterone, also known as the “pregnancy hormone,” P4 or Prog, in the ovaries, the adrenal glands and in the placenta during pregnancy.
  • This hormone promotes implantation of the fertilized egg in the uterus to establish a pregnancy and helps maintain a healthy pregnancy.
  • Progesterone is often given in fertility treatments such as in vitro fertilization (IVF) because medications used in the process reduce a woman’s natural production of progesterone.

What is progesterone & why is it important to pregnancy?

The hormone progesterone plays an important role in affecting the menstrual cycle and in maintaining pregnancy. A woman’s ovary produces progesterone, secreting it when an egg follicle releases an egg (ovulation). it is sometimes called the “pregnancy hormone,” P4 or Prog.

P4 is often given to women who undergo IVF or other assisted reproductive technologies. Medications used in such procedures can interrupt the normal production of progesterone, so supplements are given to help the body receive appropriate hormone levels. Women may also need progesterone supplements if their ovaries don’t naturally produce enough or their follicles are poorly developed and don’t secret enough of the hormone.

Before pregnancy

Progesterone prepares the uterus for pregnancy and is essential for pregnancy success, according to the American Society for Reproductive Medicine. After ovulation occurs, the ovaries start to produce this hormone needed by the uterus. P4 transforms the uterine lining (endometrium) by thickening it to receive an embryo that results when a male’s sperm fertilizes the female’s egg. Around five days after ovulation, the fertilized embryo reaches the uterus and two days later, it attaches to the uterine wall. This is right at the time when P4 levels peak.

During pregnancy

Pregnant women produce the human chorionic gonadotropin (hCG) hormone, which is a signal to the ovaries to continue to make progesterone. This prevents the onset of her menses, which is the blood and matter discharged during ovulation, and enables a woman to become pregnant.

P4 also supports a healthy pregnancy by nurturing the fetus, and a supply of progesterone to the endometrium continues to be important during pregnancy. Levels of progesterone in a pregnant woman are about 10 times higher than they are in a woman who is not pregnant. After 8-10 weeks of pregnancy, the placenta takes over progesterone production from the ovaries and substantially increases progesterone production until the baby is born.

General benefits of the pregnancy hormone (P4)

In women, the hormone estrogen stimulates growth of tissue inside the uterus. To keep the body from producing uterine overgrowth caused by estrogen, P4 slows this activity and boosts growth elsewhere. Doctors mainly prescribe it to help avoid early miscarriage and maintain a healthy level of the hormone in the uterus during pregnancy.

There are many other benefits from using P4 outside of pregnancy, including:

  • Helps burn body fat for energy, which aids in maintaining a healthy weight
  • Is a diuretic, normalizing body fluid and salt levels
  • Helps to stabilize blood sugar levels, and decrease cravings for sweet and high-sugar foods
  • Stimulates bone growth helping to protect from osteoporosis
  • Protects against arthritis and acts as an anti-inflammatory in reducing arthritic pain.

Forms of the P4 hormone

This hormone can be given as an injection or vaginally in order to deliver the hormone directly to the uterus. There appears to be no difference in the chances of becoming pregnant or continuing a pregnancy if P4 is given by injection or vaginally. Doctors may have a preference for which form of progesterone they prescribe for infertility treatment based on their experience with the different forms, which are:

  • Injections
  • Vaginal gel
  • Vaginal suppositories
  • Vaginal inserts
  • Progesterone capsules used vaginally rather than taken orally, but this method is not approved by the Food and Drug Administration (FDA).

Risks & side effects of the hormone

Many studies have been performed to look at the use of P4 during infertility treatment cycles. These studies have shown that the hormone poses no significant risk to the woman or her baby. In 1999, the FDA found that using synthetic progesterone may be associated with birth defects. The synthetic version is primarily derived from the male hormone testosterone.

Common side effects when using progesterone:

  • Headaches
  • Breast tenderness
  • Joint pain
  • Drowsiness
  • Depression
  • Dizziness
  • Fluid retention or bloating
  • Hot flashes
  • Urinary problems
  • Abdominal pain or cramping
  • Vaginal discharge.