https://www.cdc.gov/reproductivehealth/unintendedpregnancy/p...
If we had no other method, then it might be reasonable to call it effective, in comparison to doing nothing. Given that better options exist, it is not very reasonable to call it effective without qualification.
If someone chooses to intentionally reduce a conversation to an "effective/ineffective" dichotomy to deliberately mislead or obscure conversations, then it might be disinformation. Disinformation can consist entirely of factual statements.