My baby has suddenly started eating less than usual. is this usual, or is there something wrong?

Either/Or: Appetite changes may be just a normal variation. All kids through periods of greater and lesser appetites. Kids growth needs have times where they need more or fewer calories, so their appetites will reflect that. But, decrease in appetite can also be associated with illness, perhaps an illness that hasn't really shown itself well yet.If they're acting ok otherwise, keep a good eye. Call doc if ?

They could be sick: Problems feeding or significant changes in feeding patterns can be a sign that something is wrong with your infant. Every infant can vary their feeding patterns, so a happy infant, without a fever, who just feeds less during one feed, is not concerning. However, if your infants is feeding much less or if they are very sleepy and hard to arouse, you should call your pediatrician immediately.