The Baby Fat Epidemic That Isn’t

Yesterday I read the alarming headline ‘Health risks increase as newborns get heavier‘ and was not comforted by the opening paragraph:

BABIES in NSW are being born up to 21 per cent bigger than they were two decades ago, putting a generation at an increased risk of developing asthma, diabetes and cancers of the blood, prostate, breast and colon later in life.

But it appears this may be yet another media health beat up – as revealed by excellent blog Hoyden About Town.

Lauredhel has published the actual graphs that accompanied the report which the SMH story is based upon, and it appears that there has been no apparent increase in birth weight for the last five years.

The table shows the mean birthweights for male and female live-born term singletons in NSW from 1990 to 2005. The mean birthweight rose from 1990 to a peak at 2000, from about 3510 to 3540 for boys, and from about 3375 to 3405 for girls (these numbers are eyeballed; the data isn’t included.) In the old language, that’s about an ounce. A good part of that increase, though not all, is attributable to decreasing levels of maternal smoking – as the authors note.

This is a good thing right – less babies affected by nicotline in-utero?

After the year 2000, the mean birthweight FELL. Significantly. Down to about 3525 for boys, and 3390 for girls. Then it plateaued. For the past four or five years, there has been no noticeable change, and definitely no trend, in mean birthweights for either boys or girls.

But if you just read the abstract, which is as much as the vast majority of people who will quote this paper will ever read, you’d think that was a progressive or accelerating increase.

Even the percentage in SMH’s opening article is a furphy. While the amount of girl babies born large for their gestational age did increase by 21%, it’s a tricky percentage. In terms of the percentage of large girl babies born within all girl babies born in NSW, the numbers only increased from 9.1% to 11.0%.

The problem with bad science reporting such as this is that it paints modern women as fat lazy slobs who can’t put down the Tim Tams long enough to care about making an average-sized baby.

Yes we should be concerned about obesity-related health issues, but there is no evidence at the moment that obesity rates for children and adults are on a skyrocketing upwards trend. In fact, new research suggests that child obesity rates too have plateaued over the last 5-10 years. Epidemic? Hardly.  In fact, just as many children are malnourished as are obese. Yet nobody wrings their hands over those children.