The University of Auckland's Liggins Institute, which is running the New Zealand part of the trial, says the research indicates the food women eat, even before they are pregnant, can programme a baby's genes to switch on or off, influencing its risk of obesity.
Liggins researcher Professor Wayne Cutfield said that by better regulating the mother's blood-glucose levels, the experimental drink is intended to reduce risks to the fetus by "minimising the load of glucose and calories".
Lead researcher Professor Keith Godfrey, of the University of Southampton in England, said, "We think these extra supplements might switch genes on and off in a way that helps maintain healthy mother's blood-sugar levels during pregnancy. This may protect babies against obesity in later childhood."
Professor Cutfield said the study will hopefully be extended to follow the children throughout childhood.
The women in the trial are randomly assigned to receive the experimental drink or the standard one and don't know which they are given; nor will the researchers, until they analyse the results.
Harry Fox Perwick, of Torbay, Auckland, is the first baby born in the trial. Weighing 2.935kg, he arrived at North Shore Hospital on April 28. He is the first child of Rebecca Perwick, aged 27, who said the delivery was straightforward and very quick.
She joined the trial because, as a research technician at the university, she saw an internal email "looking for people interested in an area of research that's quite important".
Nutrition is important, she said, and, if not for the trial, she would have taken the recommended folic acid and iodine supplements.
Mrs Perwick said the drink tasted fine, but was hard to take when she felt nauseous.
Harry is thriving and while Mrs Perwick estimates she is getting 6-7 hours sleep, the interruptions to her sleep are, "a bit of a shock to the system".
Feeding the mum
• Trial of a new kind of dietary supplement
• Before conception and during pregnancy
• This could set up the baby's genes for lower risk of obesity and diabetesMartin Johnston health