Does Your Nutrition Affect Baby's Birthweight?
October 20, 1999
Researchers from University of Oxford in the United Kingdom report findings that indicate that maternal nutrition and smoking do not have a significant effect on the baby's birthweight. Maternal nutrition and smoking were investigated to find out what effects, if any, they have on the baby's birthweight and the size of the placenta. A growing fetus receives all the oxygen and nutrients it needs from the mother, but first they must pass through the placenta, the organ that brings the fetal circulatory system in close proximity to the mother's blood supply and where the transfer of nutrients and gases take place.
Almost 700 pregnant women participated in the study, each carrying a single fetus. The women kept weekly food diaries; answered questionnaires; and were seen on a routine basis for height, weight, blood pressure, and blood tests. To determine if they were smokers, the women were questioned, and a blood test verified their answers.
This study, which was conducted in a coastal town in England, directly contradicts an earlier study that used the population of a nearby town. The physical proximity of the two locations seems to indicate that the difference in findings is not due to social, environmental, or demographic issues.
The earlier studies had tied maternal nutrition to birth weight, as well as to future heart disease and diabetes in children.
Intake of any nutrient, such as protein, had no correlation to birthweight. Nor did it matter when during the pregnancy the nutrient was or was not consumed. The exception was vitamin C, which was associated with a slight rise in birthweight.
Smoking, however, was clearly predictive of a lower birthweight. In this study, babies born to mothers who smoked weighed, on the average, 104 g (3.5 oz) less than babies born to nonsmokers.
The controversy surrounding maternal nutrition centers on women from industrialized countries. There is no dispute that malnutrition or diets lacking in key nutrients definitely affect fetal health and birth weight. But what about women who don't suffer from these deficiencies?
This team of researchers concluded that among well-nourished women, what the mother eats has little effect on either birth weight or the size of the placenta.