I guess the parent caring for their sick child didn't call in to work either then. Yes, I have had this happen as well, so I do the concerned phone call saying I hope everyone is alright as I haven't heard whether dck is coming or not. This usually elicits apologies and serves my purpose in reminding them that I was expecting their child.
I do charge for sick days. I don't want the temptation there for clients to take a vaca or long weekend and phone their child in sick.
I hope you have a good hump day.