I'm three weeks pregnant is it safe for me to have a mri done?

Try to delay it: Certainly advise the doctors doing the MRI of your pregnancy status. They might try to take extra precautions or delay the procedure until the end of the 1st trimester. Risks to a developing baby in the first third of pregnancy are theoretical only, but current advice is that women should not be scanned during the first 13 weeks of pregnancy. I hope it goes well for you and your baby. Best wishes!

No: Recommendations for imaging (except for sonograms) are that no imaging should be done during the first trimester and later in pregnancy only emergently.

Any other options?: The truth is, there is no definite proof that MRI is safe for the unborn. Most research is limited, but shows no negative effects, but not all. Please discuss with your doctor regarding other testing options. X-rays or ct of your abdomen/pelvis would have more risk to the fetus. Finally, if there is a serious risk to you by not imaging, then proceeding with the MRI would be appropriate.