Getting pregnant with economists

Insights Newsletter
23 October, 2015

If you are planning on having a baby any time soon, I would recommend doing it with an economist. Not because of the (debatably) excellent genetic traits that could be passed down, but because it can empower parents to make informed decisions.
For instance, what should expectant mothers make of viral campaigns such as “Your child is what you eat”? I imagine a special section in the maternity ward dedicated to babies with hot dogs for limbs.
Such clarity would be useful, given the most recent intervention announced by the Minister of Health this week.
Launching the government’s “evidence-backed” plan for reducing childhood obesity, Jonathan Coleman stated that "Around 60 per cent of New Zealand mums gain more weight than recommended during pregnancy.” The Ministry of Health has even set guidelines for how much weight women should be gaining.
But here is where an economist could come in handy. Surveying the literature on weight gain during pregnancy, one very important factor is missing: causality.
Though there are a lot of studies that show a correlation between maternal weight gain and childhood obesity, it is difficult to prove that a mother’s weight gain causes their child to be obese later in life.
An overweight mother may give birth to an overweight child, but this does not mean it was weight gain during pregnancy to blame.
What are some other causes that could explain the correlation? Parents may lead by example, and pass on their poor eating habits to their children. Or perhaps there is a genetic predisposition that cannot be corrected during pregnancy.
The size of the effect also matters. Economist (and mother) Emily Oster surveys the existing studies, and argues that even if weight gain during pregnancy was problematic, the evidence suggests that the overall impact is small. Her advice to expectant mothers? “Chill out.”
And while we are on the subject, here are some other myths Oster busted using economic tools to navigate her way through the pregnancy guidebooks. Light drinking (with some caveats) is fine, just do not do vodka shots. There is no need to give up coffee, up to two cups a day is almost unanimously deemed safe. The risks associated with hair dying are overstated, while the risks of gardening and hot yoga are not.
And just to confirm, expectant mothers are overwhelmed with choices that could affect their unborn child. Eating an extra chocolate biscuit should be the least of their worries.

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