Short answer: Yes. Ovidrel, Pregnyl and Novarel are all forms of hCG, the same hormone home and blood pregnancy tests look for. The Ovidrel label says it may interfere with the reading of pregnancy tests, and MedlinePlus says fertility medicines can cause a false-positive result. The label gives a half-life of about 29 hours for Ovidrel, so the hormone takes days to clear. Fertility clinics usually set the date of the pregnancy blood test.
Pregnancy tests check urine or blood for human chorionic gonadotropin (hCG). MedlinePlus explains that the placenta makes hCG after a fertilized egg attaches to the uterus, and that levels then rise, almost doubling every three days.
A trigger shot is a dose of hCG given to finish egg maturation and start ovulation. Pregnyl and Novarel are made from hCG collected from urine; Ovidrel is a recombinant (lab-made) hCG that its label calls comparable to hCG from pregnancy urine. A test cannot tell the injected hormone from hCG made by a pregnancy.
The Ovidrel label states that it may interfere with the interpretation of pregnancy tests. MedlinePlus says that taking a pregnancy test while on fertility medicines could give a false-positive result, and that anyone on fertility drugs who gets a positive result should talk to their provider, who may need to confirm it.
| Source | Product and dose | Half-life |
|---|---|---|
| Ovidrel label | Ovidrel 250 mcg | Mean terminal half-life about 29 hours (29.2 hours median in IVF patients) |
| Radicioni 2022 (26 healthy women) | Ovitrelle 250 mcg (about 6,500 IU) | About 39 hours |
| Radicioni 2022 (26 healthy women) | Urinary hCG 10,000 IU | About 37 hours |
A half-life is the time for the level to fall by half, so it takes several half-lives for hCG to drop to very low levels. How high the level starts also varies: a 2007 study of 115 IVF patients found the hCG level the day after the trigger depended on body mass index and on the number of follicles larger than 14 mm. None of these sources gives a fixed number of days after which a home test can be trusted.
MedlinePlus describes two kinds of blood test: a qualitative test that says yes or no, and a quantitative test that measures the exact amount of hCG. Because hCG from a pregnancy rises over time while hCG from a trigger shot falls, a measured level or a repeat test can help tell them apart. The test timing is set by the fertility clinic or prescriber.
The labels also note that hCG can cross-react with lab tests for other hormones, especially LH, and ask that the lab be told when someone is on hCG.
The exact time of the trigger shot matters for egg retrieval and for reading later test results. Dose Track can log the trigger with its date and time alongside the stimulation injections, so the timeline is in one place when the clinic asks.
Read more on Dose Track: Ovidrel dosing schedule · Pregnyl dosing schedule · hCG half-life calculator · Half-life · Female fertility