My parents said I shouldn't buy baby stuff unless I'm nearing my term because of an apparent pamahiin, I suppose. Can anyone explain to me what is it?

I suppose they're worried about "usog"? I guess from a practical point of view, so much can happen during the pregnancy that's why it's safe to buy things when the pregnancy develops normally and the baby is safe and healthy. Same reason why people wait until after the first trimester to announce the pregnancy I suppose.