Of course we have to ask. While I was on one of my nursing placements, a 13 year old was admitted for treatment for her chronic disease. We asked if she could be pregnant, and she said she'd never had sex. Asked permission to take a test, parents consented.
After her parents left she told us that she'd been having sex with her boyfriend for months, and that she was pregnant but didn't know how far along. She hadn't contacted her GP or a midwife, but she wanted to keep the baby.
She told her mum, but they both refused to tell her dad until after the 20 week scan!
Her dad was so angry and worried thinking we weren't bothering to treat her symptoms, when in reality most were pregnancy symptoms, and we couldn't tell him a thing. We had to keep notes out of his sight, and weren't able to discuss most of her care while he was on the ward.
He couldn't understand why we'd stopped her medication that would have affected the pregnancy, we had to be vague about the reasons. He was on the brink of tears constantly, it was awful.
He constantly made complaints about staff which would've been justified otherwise. The patient and her mum didn't say a thing until they presented him with the 20 week scan picture. Poor bloke was relieved after all the stress he'd had.
People lie all the time.