High birth weight may be harmful, study reveals

Sydney, March 15: Contrary to popular belief that big babies are healthy babies, weighing more at birth may have adverse health implications for infants, suggests an Australian study.

Dr Ruth Hadfield, with her colleagues from the University of Sydney, conducted the study at Royal North Shore Hospital. Their study revealed an upward trend in birth weight of Australia's new-born babies since 1990, with one in six male babies weighing over four kilograms.

They carried out an in depth analysis of babies born in New South Wales between 1990 and 2005, which predicted a significant increase in babies being born overweight.

According to the data accumulated over 16 years, nearly one in six boys and one in ten girls now weigh more than 4 kg. In other words, there is an increase in weight of 10.5 percent and 15.2 percent for boys and girls respectively at birth.

High birth weight has become a potential health concern, and has been associated with an overweight child, adolescent, and subsequently an obese adult. Overweight and obesity, in turn, are associated with a host of negative effects.

Dr Hadfield reflected, “There is evidence of a relationship between high birth weight and the increased future risk of asthma, Type 1 diabetesdefine and a number of cancers, including infant and childhood leukaemia, and breast, prostate and colondefine cancerdefine.

“As well as the potential for life long health consequences, higher birth weights may also result in injury to the infant and the mother at the time of delivery.”

Researchers attribute a number of reasons for this birth-weight increase. A major factor is a decline in the levels of maternal smoking. Another reason identified is the increasing rate of maternal diabetes. An additional factor could be women bearing children late in life.

The researchers admit that the study is inconclusive with most of the reasons for high birth weight being ambiguous. Dr Hadfield stated that “Although decreasing smoking, increasing maternal age and increasing gestational diabetes account for a portion of the increase, a larger portion of the increase remains unexplained by our data.

“Further studies to ascertain all factors contributing to the increasing birth weight over time, including maternal pre-pregnancy body mass indexdefine and weight gain during pregnancy, are warranted.”

The study was published in the Medical Journal of Australia.