Why Are Hormonal Contraceptives So Effective?

Hormonal contraceptives (HC) are known to be extremely effective at preventing pregnancy and no one is disputing that. But have you ever stopped to wonder what makes them work so well?

All HCs prevent pregnancy in essentially the same way, by combining the following three actions:

  1. They interfere with ovulation
  2. They interfere with implantation
  3. They prevent your body from producing fertile cervical mucus

Hormonal contraceptives (the pill, the patch, the vaginal ring, the shot, etc) all contain a small amount of man-made estrogen and progestin hormones. These hormones work to inhibit the body’s natural cyclical hormones to prevent pregnancy.

Ovulation Interference

Hormonal birth control, such as pills, patches, rings, and injections, are formulated so that they can affect ovulation in a way that prevents the user from getting pregnant. Ovulation begins in the hypothalamus, a region of the brain that releases a hormone—gonadotropin-releasing hormone—that kicks off the ovulatory cycle. That hormone then triggers the pituitary gland, also in the brain, to produce other hormones (luteinizing hormone and follicle-stimulating hormone), which stimulate your ovaries to produce still other hormones (estrogen and progesterone) that prompt ovulation.

This trio (hypothalamus, pituitary gland, and ovaries) are referred to as your HPO axis.

As you can see, this communication within your body is like a very detailed game of telephone. (Do you remember that game from when you were a kid? The first person in the line or circle whispers a word or phrase into the ear of the person sitting or standing to their right. Players whisper the phrase to their neighbors until it reaches the last player in line. The last player says the word or phrase out loud so everyone can hear how much it has changed from the first whisper at the beginning of the circle or line.)

Taking HCs causes a break in this line of communication by interfering with the connection between your HPO axis components. In many cases, HCs completely shut down your ovaries and stop you from ovulating all together. This happened to me while on the Depo shot. Hormonal birth control uses synthetic versions of progesterone and/or estrogen to interrupt this process and prevent ovulation. If you were to take a closer look at your ovaries, you would see that they look remarkably similar to the ovaries of a woman in menopause.

However, not all HCs completely shut down ovulation. A percentage of women continue to have regular ovulation while using progestin-releasing HC, however they are still exposed to varying degrees of synthetic hormones (often continuously). And all women on HC experience some degree of HPO axis dysregulation and hormonal imbalance due to this exposure to synthetic hormones.

So if HCs don’t always suppress ovulation, how do they effectively prevent pregnancy? That’s were the other two actions come into play. All three actions work together collectively to prevent pregnancy.


Implantation Interference

Once ovulation happens, the next normal step in the cycle would be for the egg to be fertilized by a sperm. It then travels down the fallopian tube and into the uterus, where it implants into the endometrial lining. A viable pregnancy can only occur when your endometrial lining has fully developed. Estrogen supports the rapid growth of your endometrium prior to ovulation and progesterone supports the thickening/maturation of that endometrium after ovulation. Since most HCs prevent ovulation and the increase in estrogen needed for both ovulation & endometrial growth, your endometrial lining never gets the chance to fully develop. The result of this is a very thin, very flat endometrium.

Since periods are the shedding of your endometrial lining, the obvious result of a thin, flat endometrium is a shorter, lighter bleeding while on HCs compared to their real periods. Sometimes, as in my case, HCs lead to no bleeding at all because there was no lining that formed. And still, in other instances, HCs cause heavier bleeding. It varies from woman to woman and HC to HC. The results I got from the implant varied from the ones I got on from the shot and those varied from each of my friends that were on the same HCs. The journey is a very personal one, unique to each woman.

Without a sufficiently thick and juicy endometrial lining, you’re much less likely to conceive. In a study designed to measure how endometrial thickness impacts conception rates, the researchers found that women with an endometrial thickness of less than 7 mm were unable to conceive. Another study has shown that an endometrial lining of 10 mm or thicker is optimal for achieving pregnancy. Because the HCs have rendered the uterine wall inhospitable to any accidental zygote that may have formed even if you were to ovulate, a fertilized egg would have nowhere to implant, making pregnancy very unlikely.

Inhospitable Cervical Fluid

Cervical mucus has many different stages. But only one allows sperm to survive long enough to reach the egg and fertilize it. HCs thickens mucus at the cervix so sperm cannot pass through. They have nowhere to go. They can’t make it past your cervix because they can’t swim through the mucus. If the sperm can’t make it anywhere near your uterus, fallopian tubes, or ovaries, pregnancy is impossible.

Together, these three actions give HCs an effectiveness rate of up to 99.7 percent with perfect use (in the case of the pill, typical use reduces the effectiveness to about 92 percent). HCs suppress ovulation, they prevent your endometrial lining from fully developing, and they create an impenetrable death trap for sperm. In many ways, this sounds like the perfect solution for preventing pregnancy; but the question isn’t whether HCs are effective or not. The real question is: HCs are effective at what cost?

Did you use hormonal birth control? What was your experience on it and how did it effect your trying to conceive journey afterwards?

Related Posts

Make sure you grab a copy of my FREE guide 5 Steps To Increase Your Fertile Cervical Mucus & my FREE Self-Care Mini Course. You can access either one by clicking on the title. These are packed full of information that you can begin implementing today to put yourself one step closer to getting pregnant, naturally.

If you’re looking for a group of like-minded women with which to share your fertility wellness journey, be sure to check out my Whole Body Fertility & Wellness Facebook group today!

Latest Posts


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.