Effect of moderate maternal malnutrition on the placenta.

The results of two studies of the influence of moderate maternal malnutrition on the weight and chemical characteristics of the placenta are discussed. In the first study, two groups of pregnant women of high and low socioeconomic status from Guatemala City were studied. Socioeconomic status was defined by family income, educational level of the mother, and environmental sanitary conditions. Both groups were very similar with respect to age, parity, gestational age, and absence of severe disease during pregnancy. The average placental weight in the low socioeconomic group was 15 per cent below that of the high socioeconomic group and there was a consistent association between the postpartum maternal weight and placental weight. There were no differences between the two groups regarding placental concentration of fat, protein, water, ash, hemoglobin, and DNA; hydroxyproline and fat concentration were significantly lower in the low socioeconomic group. The hypothesis that the difference in placental weight observed between the two groups was primarily due to maternal nutritional status was tested in the second study by means of nutritional intervention in four rural villages in Guatemala. Two of the villages received a protein-calorie preparation while the other two received a calorie supplement. Placental weight was higher among women with high levels of supplemented calories during pregnancy, independently of the type of food supplement ingested. On the average, the groups with low caloric supplementation (smaller than 20,000 calories) had placental weight 11 per cent below those with high caloric supplementation (larger than or equal to 20,000 calories), In contrast to placental weight, the concentration of placental chemical components studied was not associated with caloric supplementation. It was concluded that moderate protein-calorie malnutrition during pregnancy leads to lower placental weight without significantly changing the concentration of the biochemical components studied. The reduction of placental weight may be the mechanism by which maternal malnutrition is associated with high prevalence of low-birth-weight babies in these populations.