A simple assessment can predict at birth a baby's likelihood of becoming obese during childhood, scientists said on Wednesday.

The formula, available as an online calculator, estimates the child's obesity risk based on its birth weight, the body mass index of the parents, the number of people in the household, the mother's professional status and whether she smoked during pregnancy.

Researchers who published a study of the test in the journal PLOS ONE say they hope it will be used to identify babies at high risk and help families take steps to stop them putting on too much weight before it's too late.

Childhood obesity is a leading cause of early type 2 diabetes, as well as various types of cardiovascular disease, and is becoming increasingly common in developed countries.

According to data from the American Heart Association, almost 18 percent of boys and almost 16 percent of girls aged between two and 19 in the United States are obese. In England, 17 percent of boys and 15 percent of girls aged between two and 15 are obese, according to National Health Service (NHS) data.

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