Composition of the human foetus

1. The body composition was determined of forty-one fetuses of different gestational ages born to mothers belonging to a low socio-economic group of the population. 2. With increasing gestational age the water content fell from 88% at 28 weeks to 76% at term; the fat content increased from 2.1% to 11.2% and the protein content increased from 6.9 to 9.3%. 3. The changes in body composition were more closely related to body-weight than to gestational age. 4. The calcium, Phosphorus and magnesium contents of the body per unit fat-free weight progressively increased with gestational age, and at term the values appeared to be considerably lower than those reported in the literature. The Ca:P ratio was constant at different body-weights. 5. The body iron content per unit of fat-free weight increased marginally with increasing gestational age. The value was almost 30% lower than the values reported from elsewhere. 6. It is suggested that chemical composition and nutrient stores of the developing foetus can be considerably influenced by the state of maternal nutrition.