Happy New Year everyone! I hope that you all had a safe and relaxing Christmas/New Years break and that 2013 has started well for you. We here at Demography is Destiny had a good break with family at a couple of different New Zealand lakes (Taupo and Rotorua). Shannon (not surprisingly) managed to be a stunning Matron of Honour at a friend’s wedding less than ten weeks after giving birth to Thomas and there were lots of grandparents and even great-grandparents ready to take Thomas when he started to get grouchy.  All in all a good time for all of us!
And, since we beat the Mayans, Demography is Destiny will continue into 2013. To start the year off, I have a story from one of our long-time readers and tipsters in Australia (our thoughts go out to our sweltering Australian cousins – the bush fires look pretty bad from over here in NZ).  Back to the story from the Sydney Morning Herald: China has the largest burden of diabetes in the world.  Not that surprising you say? After all, China should have the most diabetics since they have the most people in the world. That’s true: although China has 92.3 million diabetics, four times as many as the USA, which has 24.1 million sufferers.  However, the prevalence of diabetes in China is 8.8 per cent compared to 9.3 per cent in the USA. So really on a per capita basis, what is the story?
Well, apparently one of the reasons why China has such a large diabetes problem is the one-child policy.  While a sedentary lifestyle and the prevalence of calorie-rich food are in part to blame, researchers are also pointing the finger at the conditions in the womb.  How does that work?

“About 100 million families have just one child, the Chinese government says. That translates into an equal number of first borns, a status that researchers are finding may be tied to conditions that raise obesity risk, said Chong Yap Seng, a scientist at Singapore's National University Hospital.  Chong and colleagues in Beijing and Southampton, England, are studying the biological mechanisms that have conspired with diet and lifestyle changes to produce 92.3 million diabetics in China, almost four times as many as in the United States.

While first borns start out smaller than siblings, they gain weight faster and are bigger as adults, a trajectory that increases obesity risk and may explain why China's diabetes prevalence has more than tripled in a decade, said Chong.” Now, the researchers are only talking about the prevalence of diabetes, not the absolute number of diabetics in China. Because, of course, the one-child policy doesn’t increase the absolute number of first born babies, but the percentage of first borns in the population (since second and third and forth etc are not allowed to be born).
What is interesting is the reason why first born children are more likely to get diabetes than their younger siblings – it’s all about what happens in the womb:

“A baby that is the result of a woman's first full-term pregnancy is typically 200 grams lighter at birth than non-firstborn babies, according to Chong. First borns catch up later in life and are typically heavier as adults, according to a 2010 British study in the Journal of Clinical Endocrinology and Metabolism, which followed 276 unborn babies through to adulthood. Their smaller size at birth is probably a result of maternal constraint of intra-uterine growth, they said...A woman's first pregnancy primes placental blood supply for subsequent pregnancies, improving the availability of nutrients to the fetus, researchers at the Women's and Children's Hospital in Adelaide, South Australia, found in a study published in 2003.

Babies born during periods of famine are especially vulnerable to obesity-linked diseases as adults, Hanson said. For example, Chinese who experienced hunger as infants during the Great Leap Forward, an economic policy between 1958 and 1961 that caused tens of millions of people to starve to death, had a higher risk of developing diabetes and heart disease as adults, Harvard University researchers found in a study published in 2011. The risk was exacerbated by calorie-dense Western foods, they found.” So while the one-child policy isn’t causing more diabetics in China, it is interesting to see how our future health outcomes (I hate myself for using that phrase, yet I couldn’t think of anything else – bureaucratic speak really is penetrating into my consciousness!) are in large part determined by our time in the womb. That is, assuming that we make it out of there of course.