Personally, 19 months is a bit young for me to trust them to be careful with it. Especially considering it's a collarbone - as others have said, it doesn't get a cast, and they can be difficult to heal unless the child keeps it still. It's easy for a child that age to get excited about playing and forget that they are hurt.
I might suggest mom see about having a grandparent or friend (with fewer kids) watch him for a few weeks. If there's no chance for back up, I'd take him, but strongly suggest he take a bit of a break.
Always ensure that your child receives quality care by taking the time to investigate the provider and by asking for references! We simply cannot verify the claims of every daycare provider.
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