Estriol also called oestriol or E3 is an estrogen hormone. During pregnancy, women produce many hormones that are important to the health of the mother and baby. Estriol is a hormone that women naturally produce. However, during pregnancy, Estriol is detected at a much higher level. The amount of Estriol gradually increases throughout pregnancy, and it is at its highest shortly before birth. 

What Does Estriol Do? 

When a woman is pregnant, Estriol is produced by the placenta.  The placenta is an endocrine-related organ that develops during pregnancy and keeps the mother and baby healthy. It also prepares the mother for labor and breastfeeding. Estriol is essential because it is one way to determine an unborn baby’s health. The fetus (baby) produces hormones (chemicals) in the adrenal glands.  Then, some of these chemicals are converted inside their liver to its final Estriol form. The placenta is responsible for this final step. Estriol promotes the uterus’ growth and gradually prepares a woman’s body for giving birth. Levels of Estriol start to rise during the eighth week of pregnancy. 

What Problems Can Occur with Estriol?

Estriol is typically at its highest three weeks before birth. If Estriol significantly increases at an earlier time, it may be a sign of premature birth. 

If a woman is not pregnant, estriol levels are low. If estriol levels aren’t high during pregnancy, it may be an indication of health problems with the baby or the placenta. 

Questions to Ask Your Healthcare Team

Can my estriol levels be tested? 
What is considered a healthy level of Estriol?
What else can I do to ensure I have a healthy baby?

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