It's not that big of a deal. And it's not based on their education or whatever. I think Kashyaps try to find happiness in everything and this case was no different. I mean Suhana being pregnant is quite actually a possiblity if you look at it from their point of view. It's not like she's an unmarried 14 year old who fainted, felt dizzy and felt like throwing up. If it was, let's say Ishika, doing the same, they wouldn't have said "Oh she's pregnant!" but must have thought something else is wrong. So ya, I don't see the big deal in them thinking she's pregnant.
I do feel bad for Suhana. She looks so happy in the pre-cap. Poor girl!