Understanding How IUDs Work

Understanding How IUDs Work

When you’re not ready to have a family or want to delay your next pregnancy, an intrauterine device (IUD) may be your best choice for contraception. Today’s IUDs are simple to insert and remove, can safely be left in place for years at a time, and allow you the option of becoming pregnant whenever you choose.

An IUD is a small, T-shaped device that your gynecologist inserts into your uterus, where it remains in place for years, if you wish. An IUD is 99% effective against pregnancy. Once you have an IUD, you don’t have to think about it again until it’s time to replace it or you decide to have a baby. 

At Florida Woman Care of Jacksonville, with two locations in Jacksonville, Florida, our caring and knowledgeable OB/GYNs Daniel McDyer, MD, FACOG, and Julian Stephen Suhrer, MD, help you choose the best form of birth control for your needs. If you are considering an IUD, but wonder how a little “T”-shaped object can stop a pregnancy, read on.

IUDs change the uterine environment

An IUD is small and flexible. Once it’s in your uterus, you can’t feel it. Although every IUD is attached to a string that helps with removal, you won’t feel that, either. We cut the string close to the cervix so it doesn’t interfere with tampon use, sex, or your comfort.

Although you can’t feel the IUD, your uterine lining (i.e., the endometrium) reacts to its presence. In fact, your uterus considers the IUD a foreign object (which it is) and therefore launches a mild inflammatory response. This keeps the lining of the uterus very thin—so thin that it can’t host a fertilized egg.

Because your uterine lining thins, your period may be much lighter than normal, too. Once your doctor removes your IUD, your endometrium goes back to its normal job of thickening itself with blood and nutrients each month in preparation for a baby. Your periods return to their pre-IUD heaviness.

IUDs affect sperm 

An IUD doesn’t just affect your uterine lining; it changes the way sperm behave, too. A non-hormonal IUD that’s wrapped in copper, called Paragard®, releases copper ions that are toxic to sperm. If, by chance, an egg is fertilized anyway, the copper ions prevent it from developing. 

The plastic IUDs that release the hormone progestin — Mirena®, Kyleena®, Liletta®, and Skyla® — are also toxic to sperm. When exposed to progestin, sperm moves abnormally and can’t make its way to an egg.

Hormonal IUDs do more

In addition to the two mechanisms of action discussed, IUDs that release the progestin also have two other ways of preventing pregnancy. First, the progestin thickens the mucus on your cervix, forming a barrier against sperm.

Second, progestin stops you from ovulating. That means you don’t release an egg every month, as you normally would. Sometimes progestin IUDs are prescribed solely to make your periods lighter.

IUDs can be emergency contraception

If you haven’t yet had an IUD placed and you had unprotected sex, Paragard, Mirena, and Liletta IUDs can be used as emergency contraception. As long as they’re inserted within 5 days after intercourse, they’re 99% effective at preventing pregnancy. 

IUDs are long-lasting

Unlike most other forms of birth control, which either must be taken intermittently (e.g., shots), daily (e.g., birth control pills), or as needed (e.g., diaphragms), IUDs can be left in place for years without maintenance. Each type of IUD has a different expiration period:

Of course, you can remove your IUD before the deadline if you want to become pregnant. If you wish to continue your contraception instead, we simply remove the old IUD and insert a new one.

IUDs don’t protect against STDs

As powerful as IUDs are against preventing pregnancies, they do nothing to prevent sexually transmitted diseases (STDs). If you’re not in a monogamous, committed relationship, be sure to use condoms when you have intercourse to protect against STDs.

Though they’re small and maintenance-free, IUDs are an effective way to protect against unwanted pregnancy for years at a time. To schedule an IUD insertion, contact our supportive team at either of our two Jacksonville, Florida, locations nearest you. You can also use our online appointment form.

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