Hormonal contraception refers to birth control methods that use synthetic hormones to prevent pregnancy. This includes the birth control pill, shot, patch, implant, ring, and hormonal IUDs. But how exactly do these synthetic hormones work to stop you from conceiving?
Read on to learn the science behind different hormonal contraceptives.
Understanding Your Menstrual Cycle
First, it helps to understand how your natural menstrual cycle works. Estrogen and progesterone are the two hormones that control what happens to your body during your cycle.
Estrogen is produced by your ovaries during your cycle’s first half. It leads to a thickening uterus lining and primes your body for ovulation. Progesterone kicks in during your cycle’s second half.
After ovaries release an egg (ovulation), progesterone prepares your uterus to carry a fetus. If pregnancy doesn’t occur, progesterone levels drop, your uterine lining breaks down, and your period starts.
Then, the whole cycle begins again. This natural ebb and flow of estrogen and progesterone is what hormonal contraceptives aim to disrupt.
How Hormonal Contraception Prevents Pregnancy
Hormonal contraceptives work in a few key ways to stop you from getting pregnant. The primary mechanism is suppressing ovulation, but these birth control methods have some backup, too.
The primary way hormonal contraceptives work is by stopping ovulation, meaning an egg doesn’t get released from your ovaries each month. They achieve ovulation suppression through negative feedback to your pituitary gland.
The pituitary gland is the central control for your reproductive hormones. It gets signals from your hypothalamus and then releases luteinizing hormone (LH) and follicle-stimulating hormone (FSH) to activate ovulation.
The synthetic estrogen and progestin from hormonal contraceptives send signals that pregnancy has already occurred and ovulation isn’t needed. Your pituitary gland responds by suppressing FSH production.
With inadequate FSH, your ovaries don’t receive the cue to mature follicles each month. No follicles mean no eggs develop, and no ovulation takes place.
Without ovulating, you can’t get pregnant from sex during that time. This clever fake out of your body’s normal processes is how these birth control methods primarily work.
Thickening Cervical Mucus
Some hormonal contraceptives thicken the mucus lining your cervix, which adds another layer of pregnancy prevention. This mucus plug blocks sperm from passing through your cervical canal and traveling toward your uterus and fallopian tubes.
So, if ovulation does mistakenly occur, the thickened cervical mucus acts as backup birth control by keeping sperm from meeting up with any released eggs.
Thinning the Uterine Lining
In addition to suppressing ovulation and thickening cervical mucus, some hormonal contraceptives thin the uterine lining. This makes the wall of your uterus less hospitable for an embryo to implant and grow. Without a thick, blood-rich lining, it’s difficult for a fertilized egg to develop.
Types of Hormonal Contraceptives
Now that you understand the basic mechanism behind these birth control methods, let’s break down the major categories and how they differ:
Combined Oral Contraceptives
This refers to birth control pills that contain both hormones, namely estrogen and progestin. The most common type is the combination pill with three weeks of active hormone pills and one week of placebo pills per pack. Different brands can contain varying doses and types of hormones.
There are one-, two-, and three-phase combination pills too. These provide different ratios of hormones during your cycle week to mimic your natural hormone fluctuations.
The Progestin-Only Mini-Pill
Unlike combination pills, these contain only progestin without any estrogen. That makes them a good option if you can’t take estrogen for health reasons or experience estrogen-related side effects. Because there are no breaks from hormones, you must take mini-pills at precisely the same time daily.
The Patch, Ring, and Shot
The birth control patch and vaginal ring also use estrogen and progestin to prevent ovulation. But instead of taking a daily tablet, the patch adheres to your skin to transmit hormones. The ring is inserted into the vagina.
The Depo Provera Shot
The Depo Provera Shot is given in your arm or buttocks every three months. It is a Progestin only option so it is safe to use for women who can’t use estrogen based products. Because the progestin is delivered continuously, most women stop their periods while on Depo.
Implants and Hormonal Intrauterine Devices (IUDs)
Contraceptive implants and hormonal IUDs work a bit differently. Rather than taking regular doses of hormones, they release a steady stream of progestin over several years. Both implants and IUDs are inserted by a healthcare provider and left in place for long-term pregnancy prevention.
The Chemistry Behind Synthetic Hormones
Hormonal contraceptives rely on lab-made versions of your natural hormones to work their magic. Estrogen mimics come in two main forms:
- Ethinyl estradiol – the most common estrogen used that remains active in your body longer than natural estrogen.
- Estradiol valerate – metabolized into estradiol, the predominant natural estrogen.
There are also approximately ten different forms of synthetic progestins used, including:
- Norethindrone and norgestrel – first-generation progestins similar to testosterone.
- Levonorgestrel and norgestimate – newer progestins with greater similarity to progesterone.
- Drospirenone and dienogest – recent progestins that may carry extra health risks such as blood clots.
The ideal contraceptive hormones perfectly prevent ovulation without other hormone-related side effects. So, research continues to refine these progestin and estrogen formulations for an optimal balance of effectiveness versus safety.
Choose the Right Hormonal Contraception with Raleigh Gynecology & Wellness
When considering something as essential as birth control, having an experienced perspective matters. Raleigh Gynecology & Wellness specialists stay current on the latest advancements in reproductive science and contraceptive options.
Our team learns about your health history, preferences, and objectives to find your optimal birth control method. Contact us today at (919) 636-6670 or schedule an online consultation to discuss hormonal contraception.