Estrogens During Pregnancy: What You Need to Know

Among the most important estrogens during pregnancy are estriol, estradiol, and estrone. Discover their roles below!
Estrogens During Pregnancy: What You Need to Know

Last update: 18 July, 2021

Do you know the role of estrogens during pregnancy? Estrogens are a group of substances that are very important for the appearance of female sexual characteristics and the development of the menstrual cycle. During pregnancy, they fulfill functions that aim at preparing the mother’s body for the future changes she’ll face.

In the following article, we’ll share some general information as well as talk about their clinical usefulness in the early detection of certain conditions during pregnancy. Find out everything below!

What are estrogens?

A woman holding a cartoon image of the female reproductive organs over her lower abdomen.

Estrogens are a group of hormones that have to do with female sexual function and reproduction. They’re included in the category of steroid hormones, which means that they’re derived from cholesterol. Hence the importance of consuming this substance in moderate amounts, despite the fact that the body itself is capable of synthesizing it.

As with many hormones in the body, the levels of certain substances in the body regulate the release of estrogens. Therefore, when the body reaches optimal amounts of follicle-stimulating hormone (FSH), this stimulates the secretion of many of the estrogens you’ll see below.

Their production takes place in the adrenal glands, which, as the name suggests, are located above the kidneys, and in the ovaries. However, during pregnancy, the placenta assumes the most important role in facilitating the development of various organs destined for pregnancy.

Estrogens during pregnancy: their role

Estrogens are very important hormones and, during pregnancy, they’re largely related to the preparation of the mother’s body for the months to come. Learn more about them below!

1. Estrone

Of the three main estrogens, this is the one that the body secretes the smallest amount of. It’s of little importance during pregnancy and its secretion normally takes place in the ovaries. Like the rest of the estrogens, its function is related to:

  • Allowing for the development of the breasts.
  • Regulating the metabolism of some macronutrients, such as fats.
  • Stimulating the synthesis of collagen, one of the most important and abundant proteins in the body.
  • Induce certain mood changes.

2. Estradiol

As in the previous case, the role this plays in pregnancy is smaller than that of estriol. However, it’s likely to help carry out most of the functions intended to allow the growth of the future baby and prepare the mother’s body for childbirth.

What does estradiol do? For example, it’s responsible for changes in the blood flow to the reproductive organs. At the same time, it makes the uterine muscle more susceptible to contractions induced by hormonal changes (by oxytocin). 

3. Estriol

Once the placenta’s produced, it’s responsible for producing large amounts of estriol. In fact, the levels of this hormone outside of pregnancy are very low. In fact, during pregnancy, it increases its production by about 1,000 times its normal values. Therefore, it can be easily detected in some urine tests.

Estriol’s related to the growth of the uterus and the “softening” of the walls of the vagina, a process that gradually increases the flexibility of the organ and allows for vaginal birth.

Estrogens during pregnancy: the clinical usefulness of estriol

A doctor talking to a patient about estrogen during pregnancy.
Your doctor will advise you accordingly, when necessary.

There’s been a great deal of research regarding the possible benefits of estriol in clinical practice. Being easily measurable as the main estrogen synthesized during gestation, it’s logical to think that it could help detect some abnormalities in the mother’s health or that of her baby.

According to a publication of the U.S. National Library of Medicine, free estriol is measured along with alpha-fetoprotein, inhibin, and human chorionic gonadotropin in the so-called quadruple screening test.

This allows diagnostic guidance to be made in mothers with risk factors for the development of congenital malformations. For example, very low levels of estriol are often associated with Down Syndrome, although it’s not an accurate diagnostic test and only serves as a guide.

Other work has also studied changes in estriol concentration in the saliva of pregnant women as a predictor of preterm delivery. However, this hasn’t been completely proven.

Estrogens during pregnancy: very important hormones

Without estrogens, the development of pregnancy as we know it wouldn’t be possible. Hence the importance of knowing one’s own body and understanding pregnancy as a fascinating and complex process that must be monitored and cared for.

There are certain conditions characterized by estrogen mismanagement or secretion, although they usually appear outside the context of pregnancy. In that case, an evaluation by an endocrinologist is appropriate.

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