7 Things You Need to Know About Estrogen-Containing Birth Control
True or false? Estrogen is only found in women.
FALSE: Estrogen is a sex hormone found in both women and men. There are different types of estrogen and different target levels, depending on your gender, pregnancy status, and age. Keep reading to learn more.
1. What is estrogen?
OK, let’s start off with the most obvious question—what exactly is estrogen?
Estrogen is a sex hormone found in both women and men. However, men have much less estrogen in their bodies than premenopausal women. It is one of the 3 main sex hormones that influence sexual health and reproduction.
Most of the estrogen in a woman’s body is produced by the ovaries, but it also produced by the adrenal glands (located above the kidneys), as well as in fat cells.1
The second main sex hormone is progesterone, which might sound familiar to you if you take birth control pills. Progesterone is the hormone that prepares the endometrium to accept a pregnancy. Estrogen is primarily responsible for the process of thickening the endometrial lining. It also helps maintain pregnancy. Progestin is the synthetic form of progesterone.1
The third main sex hormone is testosterone. Although men have much higher levels, women’s bodies also naturally produce small amounts of testosterone.1
Did you know that the body makes different types of estrogen?
There are 3 main types of estrogen—E1, E2, and E3.
Estrone (E1) is the weakest form of estrogen and the only estrogen that continues to be produced after menopause. Estrone can be converted to estradiol when your body needs it.2
Estradiol (E2) is the most common type of estrogen during a woman’s reproductive years.3
When it comes to estrogen, it’s all about balance.
Studies have shown that having higher-than-normal estradiol levels may cause acne, increased risk of osteoporosis, depression, and a lower sex drive. On the other hand, having lower-than-normal levels of estradiol can lead to weight gain and increased risk of cardiovascular disease.3
During pregnancy, the body produces estriol (E3). For women who aren’t pregnant, estriol levels are very low—almost undetectable. This hormone supports uterus growth and prepares the body for delivery.3
2. What does estrogen do?
Estrogen is a powerful hormone.
In girls going through puberty, estrogen is responsible for the development of female sexual characteristics, triggering physical changes, including breast growth, the appearance of pubic and underarm hair, and the start of menstrual cycles.1
During the reproductive years, estrogen stimulates egg follicles each month and thickens the uterine lining in preparation for pregnancy. If there is no pregnancy, the lining sheds and you have your period. It also supports sexual function by thickening the wall of the vagina and supporting lubrication.2,3
Estrogen is also responsible for some nonsexual functions in the body. It supports bone health, controls the body’s cholesterol levels, and impacts both mood and how well your brain works (cognitive function).2
3. External sources of estrogen
Estrogen is naturally created in the body, but there are also external sources of estrogen or molecules that mimic it.
What are some examples of external estrogen sources?
Chances are that if you’re reading this, you have used or considered using birth control pills. Most birth control pills, known as combined oral contraceptives (COCs), contain both estrogen and progestin (a synthetic form of progesterone).3
Estrogen therapy using hormone replacement is often used to help women manage their menopausal symptoms. This therapy can be administered in various ways, including as a pill, patch, vaginal ring or skin gel.3
Estrogen is also naturally occurring in certain foods in the form of plant-based phytoestrogens. Studies around the effects of this type of estrogen in the human body have so far been mixed, with some studies suggesting it may impact hormone levels and others showing little to no effect at all. More research is still needed.3
Some common foods that contain phytoestrogens include soy, berries, seeds, fruit, and wine.3
4. What factors influence estrogen levels?
Over your lifetime, your estrogen levels will naturally fluctuate. Estrogen levels change throughout your monthly cycle, when taking external hormones, and as you age.1
Changing estrogen levels are linked to changes in mood right before your period; symptoms of PMS (premenstrual syndrome), such as bloating, acne, and feeling unbalanced; and hot flashes and vaginal dryness during menopause.1
Some situations that may impact estrogen levels include1:
● Different stages of pregnancy, such as right before giving birth when estradiol is at its peak
● Older women entering menopause when the body will naturally shift from creating one type of estrogen to another
● Specific health-related risk factors, including obesity, high blood pressure, and diabetes
5. What are some health risks of having elevated estrogen levels?
Elevated estrogen levels within the body can occur for various reasons, such as taking estrogen-containing birth control. Women who have elevated estrogen levels may experience1:
● Weight gain—especially in the waist, hips, and thighs
● Irregular periods, such as lighter or heavier bleeding
● Fatigue
● Lower sex drive
● Fibrocystic breasts (noncancerous lumps)
● Fibroids
● Depression/anxiety
6. What are some health risks of having decreased estrogen levels?
On the other hand, having decreased amounts of estrogen in the body can also lead to uncomfortable symptoms. Women entering menopause or those who have had their ovaries surgically removed are more likely to experience3:
● Hot flashes and/or night sweats
● Difficulty sleeping
● Low sex drive
● Mood swings
7. Why should some women not take estrogen-containing birth control?
Doctors recommend that certain women avoid estrogen-containing birth control options if they4:
• Are smokers who are 35 years of age or older
• Have heart and/or blood vessel problems
• Are breastfeeding
• Have high BMI
• Experience migraine headaches with aura
Before taking any form of estrogen-containing birth control, always speak to your doctor. Based on your medical history and current health, your doctor may recommend that you take estrogen-free pills instead.
Estrogen-containing pills are not recommended for women who have certain preexisting medical conditions that have been clinically shown to greatly increase their chances of serious, potentially life-threatening side effects.
Studies show that women who have the risk factors listed above face an increased risk of a condition called venous thromboembolism, which means blood clots become embedded in your deep veins.4
Also, when it comes to smoking, using estrogen-containing pills has been shown to increase how quickly the nicotine is metabolized in your body. In addition, estrogen-containing pills make your blood more likely to clot. The net result is an increased risk of having a stroke.5
Take stock of your risk factors when considering which birth control method to use. The goal is to safely prevent pregnancy.
Bonus fact: Are estrogen-free birth control pills still effective?
Yes!
For women who prefer the pill over other contraceptives or simply want fewer hormones in their pill, rest assured that estrogen-free pills are effective in preventing pregnancy.
Learn more about progestin-only pills in our article What Are Estrogen-Free Pills?
References:
- Endocrine Society. Reproductive hormones. https://www.endocrine.org/patient-isgedengagement/endocrine-library/hormones-and-endocrine-function/reproductive-hormones. Published January 24, 2022. Accessed October 25, 2022.
- Cleveland Clinic. Estrone. https://my.clevelandclinic.org/health/body/22398-estrone. Last reviewed February 18, 2022. Accessed October 25, 2022.
- Nichols H. Everything you need to know about estrogen. https://www.medicalnewstoday.com/articles/277177. Updated March 12, 2020. Accessed October 25, 2022.
- Lauring JR, Lehman EB, Deimling TA, et al. Combined hormonal contraceptive use in reproductive age women with contraindications to estrogen use. Am J Obset Gynecol. 2016:215(3):330.e1-330.e7.
- Loyola University Health System. Birth control pills increase risk of ischemic stroke. https://www.sciencedaily.com/releases/2018/03/180305092949.htm. Published March 5, 2018. Accessed October 25, 2022.