Diet in the first days of pregnancy could determine a baby's health in later life according to research at the University of Southampton, The Guardian newspaper reported yesterday. The New Scientist this week reports that after female rats mated they were fed a low protein diet for the next four and a half days, the timespan between fertilisation and implantation. Thereafter, the rats ate normally. Female baby rats born to these mothers were small, but only at birth. They then grew with unusual speed before settling down to a normal growth rate. Males were born normal-sized, but grew abnormally: they also developed high blood pressure, shrunken livers and enlarged kidneys. Scientists claim that the relationship between diet and fertility and development of a baby is puzzling. But researchers have observed that under-nourished human mothers are likely to have children with low birthweight and a tendency to obesity and diabetes later in life, as food supply improves, the British newspaper continued.