You should not become pregnant while on Depo but if you did your HPT tes would still come back positive if you were
ANSWER:
I got pregnant on my second round of depo shots, so that's certainly possible. BUT the depo prevera shot does not contain any hCG (human chorionic gonadotropin- the baby hormone) so it wouldn't affect the test. If you got a negative result, you more than likely aren't pregnant, or you took the test too early.
If you are pregnant, see a doctor because depo can affect the baby's development ( I know because I lost my baby because of it. There were chromosomal abnormalities)