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Side Effects of Progesterone in Pregnancy

author image Helen Nnama
Helen Nnama has six years of writing experience. She is a health contributor to TBR Journal, editor of fertility confidential manuals, published poet, and a greeting card writer. She has a B.S. in microbiology, an M.S. in epidemiology, and is an M.D. candidate. A former state HIV/AIDS epidemiologist and NIA fellow at Johns Hopkins, she has research experience with published work.
Side Effects of Progesterone in Pregnancy
Pregnant woman on the phone. Photo Credit SuperStock/Purestock/Getty Images


Progesterone is a hormone that is naturally produced by the body. According to the American Pregnancy Association, during the earlier stages of pregnancy, days 12 to 16 of the cycle, it is released by the part of the egg follicle known as the corpus luteum. After around week 10, progesterone is produced by the placenta. It allows for the lining of the uterus to thicken and increase, and prepare for implantation by the fertilized egg. An increased level of progesterone is required in order to maintain pregnancy and prevent miscarriage. This can cause side effects such as fatigue, headaches, mood swings and constipation.

Constipation and Headaches

According to the Mayo Clinic, increased levels of progesterone during pregnancy can lead to constipation. This occurs because progesterone relaxes smooth muscles such as that of the intestines and this slows down the passage of food through the intestines. There are decreased bowel contractions needed to allow the passage of food, fluids and wastes.

Progesterone also causes relaxation of blood vessels, which can lead to increased blood flow to the brain, and severe headaches and migraines.

Fatigue and Breast Tenderness

According to the Mayo Clinic, increased levels of progesterone can contribute to fatigue and excess sleepiness. It depresses the central nervous system, and can cause unusual tiredness during pregnancy.

According to Ohio State University, increased levels of progesterone also leads to breast changes such as increased breast tenderness and sensitivity.

Mood Swings and Stuffy Nostrils

According to the Mayo Clinic, an increase in progesterone during pregnancy can be associated with negative mood swings such as depression. The unstable levels of hormones such as progesterone can lead to mood swings in pregnant women.
Because progesterone causes relaxation of smooth muscles, it also affects the smooth muscles of the nostrils, and leads to congestion seen with stuffy nostrils.

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