When I’ve asked generically for a joke, it seems like I get an existing joke. But if you give it some specific parameters (“tell me an Ole and Lena joke about flying a kite”) then you get something structured like a joke but the punchline isn’t funny. The program doesn’t understand humor, it’s just stringing together words that are a “likely” response to your prompt

Where I live they find out the fetus’s blood type and check for mismatch. There is enough fetal dna floating around in the mother’s blood to check things like blood type, gender, and chromosomal abnormalities (like Down’s syndrome).

Presumably someone using only condoms would have a missed period as a hint that they need to take a test, while many women on continuous birth control have infrequent or no periods so wouldn’t otherwise notice something was different.