However, the researchers said that despite a lower number of invasive tests, the heavier reliance of this method on chorionic villus sampling earlier in pregnancy could actually mean an increase in the number of healthy babies lost if the miscarriage rate using this method was closer to 2%.

BBC: Down's test miscarriage warning

Because the 1990 Census undercounted millions of Americans, mostly minorities, the Clinton administration proposed the sampling method as a way of ensuring a more accurate count in 2000.

ECONOMIST: Sampling is wrong: official

This concern, however, is being allayed with the advent of techniques such as Dr Song's mobile-sampling method.

ECONOMIST: The biology of business