What Is the Connection between Estrogen and Estradiol?

Nicole Madison
Nicole Madison

The connection between estrogen and estradiol is that they are both hormones and are very similar to one another. Estrogen is a hormone important for sexual reproduction, and it is the primary sex hormone in human females. Estradiol is a form of estrogen that is produced by a woman's ovaries and is important to sexual organ development and reproduction. The other primary types of estrogen are estriol, which is dominant in pregnant women, and estrone, which is dominant in menopausal women.

Anatomical model of the human body
Anatomical model of the human body

Estrogen is a sex hormone that is often discussed in regard to its importance in reproduction, the menstrual cycle, and even the treatment of annoying symptoms of menopause. There are, however, various forms of estrogen, which is how estrogen and estradiol are connected. Estradiol is the main type of estrogen in a woman who is not pregnant. The two other primary estrogens are referred to as estriol, which is the form of estrogen a woman's body usually produces while she is pregnant, and estrone, which is the main form of estrogen produced when a woman is in menopause.

The estrogens that circulate in the female body, including estrogen and estradiol, are produced by a woman's ovaries or by the placenta during pregnancy. Follicles in the ovaries, which develop and mature eggs for release at ovulation, produce estradiol. The placenta, which helps to sustain a developing fetus, produces estriol. Though the various forms of estrogen and estradiol are important throughout a female's lifetime, estradiol is most important in the time leading up to ovulation. During this time period, it helps with thickening the lining of the uterus to prepare for a fertilized egg and making cervical mucus hospitable in case of incoming sperm.

It is important to note that most people do not distinguish between the different forms of estrogen when they are discussing this type of hormone. Instead, they usually use the word estrogen in a generic sense. Then, if there is a reason to discuss a particular form specifically, they may specify that they mean estradiol or another type. For example, many women who are hoping to conceive have fertility testing in day three of their menstrual cycles, and these tests typically check the level of estradiol present. Likewise, doctors might test estrone levels in menopausal women or those with certain ovarian and uterine conditions, and they may also test estriol levels in women who are experiencing high-risk pregnancies.

Nicole Madison
Nicole Madison

Nicole’s thirst for knowledge inspired her to become a wiseGEEK writer, and she focuses primarily on topics such as homeschooling, parenting, health, science, and business. When not writing or spending time with her four children, Nicole enjoys reading, camping, and going to the beach.

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Discussion Comments


@ElizaBennett - My doctor had told me about the lower estrogen during breastfeeding. He said that's why breastfeeding seems to help protect against breast cancer; basically anything that lowers your lifetime exposure to estrogen (like if you happened to be a late bloomer) will help with that.

I have one of those aunts who's a bit too forthcoming (single lady, active social life) who was telling me all about the estrogen options post-menopause. Apparently, you can use an estrogen cream or something like that inside your vagina instead of having to take pills or shots. That way, it doesn't enter your system as much and you don't have as much risk of serious side effects, but you can still treat dryness.


Something that a lot of women don't realize is that after your baby is born, your estrogen levels will be low while you're breastfeeding. The lower estrogen tends to reduce your interest in sex (as, of course, does being up several times a night and generally having a tiny person hanging on you all the time) and can even make it uncomfortable because low estrogen can mean vaginal dryness.

I breastfed both my children and it was a wonderful experience; I certainly wouldn't want to turn anyone of it. I mention this consequence only to help people have realistic expectations and to help them wait it out. If you understand why your desire is low and why sex is painful, you can be more patient with yourself (and hopefully your partner will be, too).

Estrogen is *supposed* to be low during breastfeeding, but some doctors will prescribe hormonal contraception to breastfeeding moms, even pills with estrogen. The estrogen can drop your milk supply, so I recommend against it! And the minipill, which only has progesterone - well, that's not going to do your libido any favors. You might be better off using a barrier method or, if you want something hassle-free, maybe an IUD. (They are expensive but your insurance may cover it.)

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