How reliable are expired pregnancy tests? (Even if it's just by a few months)

Sam

FINALLY got my BFP and I was honestly not expecting it. I feel pregnant but its still a few days early. So of course I got all jittery and excited and then noticed the test expired a few months ago 🤦🏻‍♀️ so now I'm just bummed. Obviously I'm going to buy a bunch later this afternoon but thought I'd look for advice here. I know false positives are rare, but is that the case with expired tests? Any one have any experience with it?