IUD Pregnancy?

Q: I have an IUD in place...and a positive pregnancy test! I'm concerned for the fetus. What are the stats on babies concieved when mom has an IUD? Process of removal of IUD? Risks? Help!

A: At 99% effectiveness, IUD's (also known as IUS: Intrauterine System) are one of the most effective forms of birth control. But occasionally pregnancy happens anyway. If you have an IUD and are pregnant, you need to get an ultrasound as soon as possible. This will:

1. Rule out ectopic pregnancy.
2. Rule out a "lost" IUD - sometimes they can fall out and the lack of their presence is the cause of the pregnancy! (How one can lose such a thing and not notice is beyond me...but then again, some women make it to labor without realizing they are pregnant.)
3. Show where the IUD is and where the baby is in the uterus. Leaving the IUD in can cause miscarriage and preterm labor (no birth defects). Taking it out can also cause miscarriage! In most cases, it is safer to take the IUD out than leave it in, but that is something that will have to be determined by a doc on a case by case basis.

I've tried to find stats on which is riskier, but to no avail. If anyone out there knows where they can be found, I welcome the pointer!