What Causes Low Estriol?

November 19, 2021

What Causes Low Estriol?


Estriol is one of three kinds of estrogen produced in a woman’s body. It has many essential functions when it comes to supporting a healthy pregnancy. But when you’re low on this vital hormone, problems can occur with the developing fetus and sustaining a normal-length pregnancy. So the question then becomes, “What causes low estriol?” In this article, we’ll look at this inquiry in more detail.

What is Estriol?

Both men and women generate estrogen but in higher amounts for women. It helps develop female characteristics, regulate the menstrual cycle, fertility levels, and maintain a healthy pregnancy. Estrogen comes in three primary forms: 


  • estrone (E1)
  • estradiol (E2)
  • estriol (E3)


Estrogen before pregnancy is made primarily in the ovaries and helps to stimulate ovarian follicles to maturation. Each strand contains an egg that, once ready, drops from the ovaries into the fallopian tubes looking for fertilization. The form of estrogen responsible for this reproduction activity is estradiol or E2. 


Estrone or E1 becomes the dominant type of estrogen after menopause. Menopause is when all reproduction comes to an end for women. The trigger for this is different factors, but the main one is a significant drop in estradiol. After this happens, only the weakest form of estrogen becomes prominent. Therefore, E1 is the weakest form.


But if pregnancy occurs, E3 or estriol becomes the main estrogen circulating. The detection of estriol usually happens by week 8 of pregnancy and peaks right before birth. Estriol comes from the baby’s developing adrenal gland, which secretes dehydroepiandrosterone-sulfate (DHEA). 


The placenta takes the DHEA and converts it to estriol, and diffuses into the mother’s body. Thus, the symbiotic connection between the fetus and mother in making and using estriol is essential throughout the pregnancy. 


What Does Estriol Do?


Estriol levels usually can’t be detected before pregnancy. However, once the placenta is fully formed around 8-10 weeks, estriol becomes the dominant type of estrogen. It indicates the health of the pregnancy. Normal levels indicate normal fetus development. 


Estriol helps grow the fetus and reception to other vital hormones like progesterone during pregnancy. Some experts think that peaked estriol levels indicate delivery is close and low levels show that it is not or that labor needs to be induced.

What Causes Low Estriol?

It can be hard to determine what causes low estriol levels for pregnant women. But one major cause may be adrenal insufficiency. 


May Be Adrenal Insufficiency


Adrenal insufficiency is when the adrenal glands in the developing stage have difficulty producing enough DHEA. DHEA is a precursor hormone, meaning that parts of the compound convert to other hormones, like estrogen and progesterone. If the adrenals have difficulty making DHEA, then the placenta doesn’t have enough to convert to estriol during pregnancy. 


May Be Steroid Sulfatase Deficiency


Asteroid sulfatase deficiency is a rare genetic disorder that can result in ichthyosis. Ichthyosis affects males only and is a skin disease that causes brownish scales to appear post-birth. The condition comes from the mother, affects male children, with rare exceptions females.


Ichthyosis isn’t very common, but one indicator seems to be that estriol levels were low during pregnancy. Or women may have experienced a delay in labor or had a failure of delivery to start. 


Pregnancy health tests, such as estriol levels, may detect the possibility of ichthyosis during pregnancy due to the link of low estriol levels. 


May Be Prescription Drug Interactions


Some drugs may cause estriol levels to become lower for pregnant women. Drugs that may interfere with estriol production are corticosteroids and propylthiouracil. 

Corticosteroid Treatments


Corticosteroids are anti-inflammatory drugs that help control rheumatologic diseases, such as lupus rheumatoid arthritis or vasculitis (blood vessel inflammation). The man-made corticosteroids mimic the natural hormone cortisol. 


Cortisol comes from the adrenal glands and helps reduce inflammation and activity of the immune system. They may be administered directly on the affected skin or administered to flow throughout the body. Some examples of localized steroid treatments include eye drops, skin creams, or joint injections. 

Propylthiouracil Drugs


Propylthiouracil is primarily used to treat an overactive thyroid gland or hyperthyroidism, Grave’s disease, or a toxic goiter (enlarged thyroid). 


It works by inhibiting the thyroid from making the thyroid hormone. However, taking propylthiouracil for too long can cause liver damage for some people. 

May Indicate Problems With Pregnancy

Women with lower estriol levels may have a higher risk of pregnancy complications and trisomies (Down’s syndrome). The pregnancy complications include a fetus not developing normally, miscarriages, and preterm labor. It may also indicate preeclampsia, a severe pregnancy complication resulting in high blood pressure and early delivery. 


Low estriol levels can be unexplained, but it could mean there’s a problem with the placenta. The placenta is an organ produced during pregnancy that the baby’s umbilical cord links to and becomes vital for carrying a normal pregnancy to birth. 

May Be Menopause Related


Menopausal symptoms like hot flashes, weight gain, moodiness, and others come from low estrogen levels. Going through menopause starts with a plummet in estrogen levels. 


Even though estriol is the primary form of estrogen during pregnancy, hormone replacement therapy for women experiencing menopause can include this form in treatment. 

Improving Estriol Levels 


Detecting low estriol levels early in pregnancy is critical for treatment. Pregnant women should speak to their healthcare practitioner for the best option for their health. 


However, common treatments include hormone therapy with estriol creams, DHEA therapy, or a combination. Adding back the missing estrogen may help ease symptoms. Also, since estriol comes from DHEA, boosting these levels can have a positive effect. Looking at your diet and incorporating estrogen-promoting foods may help as well. 


In any case, the causes of low estriol can come from many sources, but in most cases are pregnancy-related since this is the dominant estrogen form. However, prescription drug treatments can have an effect and menopause.