How IUDs Actually Work

So we've all heard of the IUD, but how does it actually work? When we ask our friends about theirs, all they can tell us is usually along the lines of...

  1. "I don't really know... it blocks sperm?"
  2. "It has hormones that prevent pregnancy!! ...Except the copper one—that one doesn't."

It sounds too good to be true. Let's take a step back and go behind-the-scenes with to your little "T" friend, the IUD.

Image via NPR

The IUD is not just a physical barrier between sperms and unfertilized eggs. It does even more to prevent fertilization.

Levonorgestrel IUD

Like the contraceptive pill, the IUD releases hormones that kill sperm on contact and discourages your uterus from ovulating. This is called progestin: the synthetic version of the naturally-produced steroid hormone progesterone. Progestin is also found in the contraceptive pill, along with estrogen. Some IUDs release a progestin called levongestrel. "Lev" acts as a spermicide by creating inflammation during intercourse that travels from your uterus down to your vagina, and kills sperm upon contact. You could picture it as a contraceptive storm raining little "Levs" down all over your vagina. This hormone also thickens discharge, fortifying your uterus from the swimmers. 

Copper IUD

Some women are more sensitive to increased hormone levels than others, for whom exists copper IUDs! Similar to levongestrel, copper ions act as a spermicide without increases the level of natural hormones in your body. This non-hormonal technology does, however, have its downsides. While it's sparing women PMS, women with copper IUDs do experience a heavier flow and some cramping during menstruation.


Just to clarify, there are two types: levonorgestrel (hormonal) and copper (non-hormonal). 5 brands exist in the U.S. and each are different: 

Image via Free IUD

If you have an IUD and are unsure how it works, ask your doctor or do some research online. If you are interested in getting one, schedule a consultation and talk about which would work best for you! Not all women love their IUD, so consider side effects, know your body, do your research, and shine bright like a copper "T" or "Lev" life to the fullest!