Unless you have something contagious (cold sore, flu etc) you can kiss your baby.
Kiss your baby all over, Espeiclaly if you’re breastfeeding.. u take in everything in their body and make antibodies with your breast milk.. and I agree with Charni.. nobody else should kiss your baby on the face or hands.
On their body**
It’s good for them to get as much affection as possible, hugs and kisses. Please don’t listen to mother in laws. I don’t know where they get this from
I won't kiss my baby on the mouth because I have HSV-1 (coldsores). About 85% of the population (depending where you live) have it and most people don't get symptoms so even if you don't get coldsores I would avoid it. It's a really easy thing to do to possibly avoid a lifetime with it/the pain. Babies have lower immune systems, obviously, so they can still get hsv-1 even if you don't display symptoms.
You can kiss your baby anywhere, that's YOUR baby.. your MIL (or anyone else) however shouldn't kiss babys hand or face etc..