The health and well-being of every child is affected by both the quality and quantity of food, but when does nutrition first begin to be important? Is it after the birth or from the moment of conception, or perhaps even before this? This paper will focus on the nutritional status of the mother, before as well as during pregnancy, and its relationship to the birth weight and subsequent health of the child. Pre-pregnant weight is a major factor affecting birth weight; underweight women may be at increased risk of delivering a low birthweight infant and of complications of pregnancy, whilst those who are excessively obese are at greater risk of gestational diabetes and hypertension. Animal studies have demonstrated that severe vitamin and mineral deficiencies have dramatic effects on reproductive outcome, and there is now growing evidence that even marginal deficiencies in women may have deleterious effects on pregnancy outcome. Nutrition interventions which involve low-risk women appear to have little effect but beneficial effects have been demonstrated in interventions directed at high-risk women. Information about nutrition should be the mainstay of any advice given to prospective parents.