Answer: To the possibility of infection? Way overreacting. At least, in this layman's opinion.
Please run this plan by your pediatrician - not only because I think your fears are disproportionate in this case, but also because letting fear guide your child-rearing decisions is an unhappy path. So is taking a "sanitize me" approach, since bodies equip themselves to fight infections through exposure to germs, and a gown mentality could set your baby up to be sickly down the road.
I might even go so far as to suggest you get screened for anxiety or OCD, given the extreme measures you're considering. Still - the threats from your in-laws are just bizarre.
Question: I'm disappointed in your response. I generally have a "more dirt is better" approach - but for that first month or so, we were of the wash-and-sanitize variety. Newborns who get infections have far more risk than even older infants. New motherhood is stressful and filled with the opportunity to second-guess and feel guilty. If a few months of precautions let her sleep better, it's insane to give in to bullies for the sake of their convenience.
Answer: I'm all for ignoring bullies, and the bullies are not why I flagged her sterile-arms-and-gowns approach. I also don't expect people to ignore cleanliness around newborns; I used and support reasonable precautions.
But gowns, around a child who is not premature or known to have health problems? The reason I suggested she talk to their pediatrician has nothing to do with the in-laws and everything to do with getting off to a markedly fear-driven start.
My advice to any new parent is to learn to take a fact-based approach to risk, since there's no way to eliminate it entirely and it's more costly when it's mismanaged. (As in, when people go to great lengths to protect against a perceived risk that isn't statistically much of a threat, and in the process ignore something mundane - like constant fretting about risk - that could have a huge negative impact on the child's life.)
Getting into the habit of lining up reasonable and informed advisers, books included, and using them as questions like this one arise is a wonderful long-term investment.
E-mail Carolyn Hax at email@example.com.