There is little doubt that the mother's state of protein-energy nutrition affects birthweight and intra-uterine growth generally. The state of nutritional balance (i.e. intake minus expenditure) during the second trimester is probably more important than dietary intake alone. Not all mothers producing poorly grown babies are undernourished, however, so that preventative and therapeutic measures should be aimed only at those who require them. As with many other aspects of medical practice, unnecessary treatment can have adverse effects. The effect of maternal nutrition on intra-uterine growth is one more reason against adopting a plethora of local intra-uterine growth standards. Just as for postnatal growth, international reference data of weight (and other measurements) for gestational age should be established and accepted, against which the growth of all babies irrespective of geographical, ethnic or economic background, may be compared. These international reference data should allow for sex of the baby, parity and maternal height. They should not allow for smoking, weight, diet, physical activity. "FIGOFeGS" (Fédération Internationale de Gynécologie et d'Obstétrique Fetal Growth Standard) is proposed.