The federal government is attempting to ease fears that new hygiene guidelines will mean children cannot blow out candles on birthday cakes at child care centres.

The latest National Health and Medical Research Council (NHMRC) guidelines, titled Staying Healthy, are aimed at preventing the spread of viruses and diseases among children.

But Early Childhood and Childcare Minister Kate Ellis, who launched the guidelines on Tuesday, is fighting concerns they go too far.

"Just to be clear - there are no rules for child care centres on birthday cakes and they can determine their own policies and procedures," she wrote on Twitter on Wednesday.

The guidelines state that children should not blow out candles on a birthday cake to be shared with friends to avoid spreading germs - a suggestion the Australian Medical Association (AMA) warns may put kids in a bubble.

"To prevent the spread of germs when the child blows out the candles, parents should either: provide a separate cupcake (with a candle if they wish) for the birthday child and enough cupcakes for all the other children (or) provide a separate cupcake (with a candle if they wish) for the birthday child and a large cake that can be cut and shared," the document states.

Another guidelines stresses that children should wash their hands before and after playing in the sand pit, using alcohol sanitiser.

AMA president Steve Hambleton said it was normal and healthy for children to be exposed to a certain amount of environmental antigens that build their immune systems.

"If you live in a plastic bubble you're going to get infections (later in life) that you can't handle," he told News Limited.

Ms Ellis has been approached for further comment.