Previous research into gestational growth has taken ethnic origin but not living conditions into account. Where mothers of a similar social, economic and health status are compared, the Oxford team has shown, healthy West Indian babies will grow at the same rate as healthy, well-nourished Britons.
The women enrolled into the second part of the INTERGROWTH-21st Project – whether in Pelotas, Brazil, or Naigpur, India – were carefully selected to achieve a like-for-like comparison: urban women of similar age with a healthy BMI who were non-smokers and living in a clean environment. “It is important to say these were not superwomen, they were simply well-educated and well-nourished,” says Kennedy.
“In the centres we selected, one-third of the women met our criteria for being healthy. So this wasn’t a tiny slice of the population.”
Babies were weighed and measured (including head circumference) at birth, then at one and two years of age. The team tracked fundamental motor milestones according to WHO norms, such as the age at which the child first stood or walked alone, but also developed its own, culturally neutral set of tests for visual acuity, attention span and language development.
At the age of two, the children were given a series of play-related tasks. “You might build a tower using five blocks, then knock it down,” says Michelle Fernandes, the Oxford researcher who devised the tests. “Will the child respond by building another tower, completely or partially, or make no effort to do so? If you place a number of objects in front of the child – a cup, spoon, sock, shoe and cube – and ask them to put the spoon in the cup, without giving them a visual cue, are they able to do so?”