Any cat moms also human moms?

I have two cats, 1 year old and 8 months old, and I have a son, 2 months old this week. My cats were being great with baby up until this past week. They’ve started pissing on anything that’s the baby’s. They peed on his bouncy seat twice and in his cradle once. My fiancé thinks they’re becoming jealous and marking their territory. Is there anything I can do to stop this? I don’t want to get rid of them but this is unacceptable.