Hair from the scalps of pregnant women is offering Auckland-based medical researchers vital information about the growth of unborn babies - which could ultimately help to combat obesity and diabetes.
Research led by Gravida, the National Centre for Growth and Development, has already broken new ground internationally and is being extended with a grant from a foundation set up by Microsoft founder Bill Gates and his wife Melinda.
The US$100,000 ($130,000) grant will allow a team supervised by Gravida director Professor Philip Baker to investigate using mothers' hair to predict impaired brain development in babies while they are still in the womb.
Although Dr Baker acknowledges the idea is still "quite speculative", it follows a trial in which the team has identified marked differences between the chemical composition of hair taken from mothers of normal-sized babies and from those of infants whose growth was restricted in the womb.
The Auckland researchers, including post-doctoral fellows Karolina Sulek and Morgan Han, "blind-tested" hair samples from a cohort of 83 Singaporean women - half of whom gave birth to under-sized babies - and found marked variations in a range of chemicals including amino and fatty acids.
Since their findings were published in a scientific journal in July, they have begun extending their investigations to expectant mothers in New Zealand, Europe, and China.
The Gates' grant will help them to gather hair samples from African women and to follow up the research by examining the brain development of children once they reach their second birthdays.
Dr Baker said big advantages of hair over blood or urine samples were that it was far more stable and easy to preserve.
"If I looked at your profile [from urine or blood tests] it would be different to that of everybody else on the planet, but if you had a curry or a big steak it would change with the meal," he said.
"The advantage of studying hair is it gives a much more stable picture, so we decided to see if we could predict which babies were failing to thrive in the womb."
Although it was far too soon to predict treatment strategies for under-sized fetuses, Dr Baker acknowledged that greater certainty in detecting small babies would help obstetricians such as himself to judge whether and when to induce childbirth in mothers in advanced pregnancy.
The research had potential wide-ranging implications for the health of people throughout their lives.
He acknowledged that hair samples had long been used to test for drugs or poisons, and he was a little surprised the concept had not been extended earlier to other diagnostic ends.
But he said analytical tools were now becoming more sophisticated, allowing greater precision.