I have heard a similar story from my neighbor before (she knew the parents who lost their baby). The parents sent their baby to a Chinese couple, who came to USA to visit their child here. We do not expect them to treat the baby as their own grandchild. However, quite often they do not follow the normal procedure. For example, the babies needs to be burped after they finish their bottle of milk. However, the old lady did not do this. And the baby died from that.
I have saw the way that my previous neighbor's parents treat the baby who were sent to them. They took the baby outside once. The baby was so fond of the sunshine and he "asked" them to go out again the next day using his body language. However, he was never taken out again! That couple themselves told my in-laws this, commenting that the baby is easily spoiled. I felt very sad for that baby, and decided that I would never hire a private person to care for my baby.
I do not know what happened to the caretaker or the parents who lost their baby in my old neighborhood. But lessons need to learned. Do not think it is safer to give your baby to some Chinese old lady. If you or the grandparents can not take care of the baby, it is safer to send him/her to baby care center. The baby probably will catch some mild disease quite frequently, but they will be burped there.