Peaceful Pregnancy

How Progesterone Helps

By Lisa A. Goldstein

A popular misconception about progesterone is that it's unsafe. The warning, "Do not take if nursing or pregnant," that sometimes appears on a progesterone prescription adds to this belief. This warning refers to the progestins that are used as contraceptives, says Dr. Susan Ramin, director of the Maternal-Fetal Medicine Division at the University of Texas Medical School at Houston.

Dr. Ramin led research at her school for a National Institutes of Health study to test whether weekly injections of 17 alpha-hydroxyprogesterone, or 17P, a progesterone-derived hormone, prevented preterm births. Of those who received the progesterone treatment, the risk of preterm birth before the 37th week of pregnancy was reduced by 34 percent. The preterm birth risk prior to 32 weeks was reduced by 42 percent.

The use of 17-hydroxyprogesterone – a metabolite of progesterone – is safe for both Mom and Baby, says Dr. Ramin. Both progesterone and 17-hydroxyprogesterone are produced in large amounts mostly by the placenta in human pregnancies. Progesterone itself is a naturally-occurring steroid secreted by the ovary, placenta and adrenal gland. Animal and human studies have not shown any related birth defects in offspring with 17-hydroxyprogesterone.

Studies on this topic are often misunderstood and bolster the opinions of some who are convinced that progesterone is unsafe during pregnancy. For example, Dr. June Reinisch, director emeritus and senior research fellow at the Kinsey Institute for Research in Gender Reproduction, reports her findings have been misinterpreted significantly.

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