Pregnant mothers are being warned that the likelihood of their child being overweight in later life can be influenced by factors determined before they are born.
A first-born, premature or post-term child has an increased chance of being obese and developing diabetes later in life.
Professor Wayne Cutfield, director of the Liggins Institute at the University of Auckland, says obesity needs to be prevented earlier rather than being "inadequately addressed" later - and that includes debunking the cliche that it is okay for pregnant women to binge by "eating for two".
Professor Cutfield, who is speaking in Auckland at a transtasman obesity society meeting, said stronger education about healthy eating needs to be tailored to target women from their early teenage years.
He said a woman's health before pregnancy reflected on her child's health for the rest of its life.