Which Fertility Drugs Cause False Positives on Pregnancy Tests

If you're taking fertility drugs, you've probably come across stories of women getting false positive pregnancy tests. But not every fertility drug causes this -- far from it.

Which drugs don't cause false positives

If you're taking Clomid or Femara (Letrozole) to induce ovulation, you don't need to worry about a false positive. So if you're reading this after a Clomid cycle wondering if your positive test is real: yes, it is.

Which drugs do cause false positives

A very popular drug used to trigger final egg maturation right before egg retrieval (in IVF, IUI, or timed-intercourse cycles) is Ovidrel, or brand equivalents Pregnyl and Novarel -- commonly called "trigger shots." Their main component is hCG. And hCG is exactly the hormone pregnancy tests detect. So any test taken soon after a trigger shot will read positive, regardless of whether you're actually pregnant.

How to change your approach to testing

• Test out the trigger shot: test daily after your shot and wait for the line to fully disappear. If it reappears or gets darker days later, that's a genuine pregnancy.
• Wait for your official test date: your clinic will typically give you one specifically calculated so any hCG detected is from you, not the medication.

Whichever approach you take, a highly sensitive test makes the "line disappearing" method easier to read clearly.