The frequencies of several common antenatal disorders increased in the U.S. Collaborative Perinatal Project when women had low pregnancy weight gains. The case fatality rates of a much wider spectrum of antenatal disorders increased with low weight gains. There is indirect evidence that these high case fatality rates were mainly due to sub-optimal maternal blood volume expansion, with resultant low blood flow from the uterus to the placenta. Metabolic acidosis, related to maternal fasting, may also have contributed to the perinatal mortality associated with low weight gain. To avoid acidosis, women should be advised not to fast during pregnancy.

There is evidence that maternal overnutrition during pregnancy sometimes predisposes to hypertension. This type of hypertension is relatively benign by comparison with the hypertension associated with low pregnancy weight gains. Finally, dietary deficiency of zinc appears to predispose to amniotic fluid bacterial infections, a major cause of preterm labor and delivery. (BIRTH 10:2, Summer 1983)