A Guide to Progesterone

Progesterone is an essential, naturally-released hormone released by the corpus luteum. With several vital roles in the women’s body, both low progesterone and high progesterone can have detrimental effects on fertility and the menstrual system.

Progesterone, though created naturally, can be synthetically made in a lab to mimic the effects of the natural hormone. Progestin, an artificial lab-created derivative of progesterone, is found in several birth control pills, most notably progestin-only contraception. 


What Does Progesterone Do?


Progesterone has an important place in the female reproductive system. For women who aren’t pregnant, a healthy progesterone level regulates periods. The hormone will assist in thickening the lining of the uterus. This will help substantiate a habitat for a fertilized egg should one occur. 

Progesterone also has an essential role for women who are expecting or trying to get pregnant. Not only does progesterone assist in the healthy and accurate implantation of a fertilized egg, but it’ll begin to work overtime, ensuring a healthy and full-term pregnancy. Progesterone also supports milk production in postpartum women. 

A synthetic replication of this hormone may be given in menopausal women to ease the side effects of menopause. 

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Progesterone Level in Pregnancy

For women who aren’t pregnant, progesterone is released by the corpus luteum; However, once implantation occurs and the placenta develops, the placenta will begin to release progesterone. This process usually occurs between weeks 8 to 12. 

Due to the stimulation of progesterone in the placenta, progesterone levels can reach anywhere from 65 to 290 ng/mL by the third trimester of pregnancy. This is significantly higher than the 2 to 25 nl/mL in the women who are not pregnant. Progesterone levels rise to maintain a healthy pregnancy and stimulate milk production postpartum. 


Progesterone Imbalances


Due to the vital role that progesterone plays in the reproductive system, a progesterone imbalance can wreak havoc on different systems. Women can have too high or too low progesterone levels, which cause significant discomfort and side effects. 


Low Progesterone

Women who struggle with low progesterone levels may have a challenging time getting or staying pregnant. Because progesterone helps thicken the uterine lining, low levels will cause a thin lining, making it especially difficult for the egg to implant. 


Low levels of progesterone in pregnancy can lead to miscarriage.

Symptoms of low progesterone in non-pregnant women:

  • Irregular menstrual cycle 
  • Infertility 
  • Headaches
  • Hot flashes
  • Weight gain  
  • Fibroids


Those who suffer from low progesterone often have high estrogen levels. The body will overcompensate with estrogen to make up for the lack of progesterone. High estrogen levels can lead to weight gain, mood swings, breast tenderness, and a decreased libido. 

To supplement low progesterone levels, patients may be offered the following treatment options:

  • Vaginal creams
  • Topical creams 
  • Suppositories
  • Oral medications 
  • Hormone therapy 

High Progesterone


High progesterone levels can also lead to some unfavorable conditions. High progesterone levels can result from pregnancy, ovarian cysts, molar pregnancy, or congenital adrenal hyperplasia. 

Symptoms of high progesterone in non-pregnant women: 

  • Premenstrual symptoms
  • Breast tenderness
  • Bloating
  • Mood swings
  • Food cravings 
  • Nipple sensitivity 

Progestin Only Birth Control


Progesterone is the naturally occurring hormone in the female reproductive system, and progestin is a synthetically created form of progesterone. Progestin is used medically, often in progestin-only birth control. 


Progestins work with progesterone receptors in the body to replicate the effects of progesterone. Because of this, they have similar effects on the female body. 


Progestin-only birth control, also known as the minipill, can be highly beneficial for a significant portion of the female population. This method of contraception is especially recommended for: 

  • Women over 35
  • Women with high blood pressure
  • Women who suffer from migraines
  • Women who are breastfeeding 
  • Women with a history of blood clots 


Minipills thickens cervical mucus and thins the endometrium. This challenges the sperm from reaching the egg. The minipill will also halt ovulation. 




Released by the corpus luteum in non-pregnant women and the placenta in pregnant women, progesterone is an essential hormone in the female body. To have a healthy pregnancy and regular menstrual cycles, progesterone must be at an appropriate level. Side effects will occur when progesterone is too low or too high, including weight gain and mood swings. Should you suspect a progesterone imbalance, speaking to your doctor is imperative.