Iron, zinc and vitamin C nutritional status is not related to weight gain in pregnant women

To evaluate if the pregestational body mass index (BMI) and weight gain during pregnancy permits the identification of cases with high risk of developing specific nutrient deficiencies (iron, zinc, vitamin C), a follow-up study was done on a group of apparently healthy pregnant women, evaluated at weeks 16, 24 and 34. Pregestational weight was recalled by the women, while gestational weight and height were measured. Hemoglobin, leukocyte vitamin C and serum zinc and ferritin were determined from venous blood samples. The sample was divided for analysis according to BMI and gestational weight gain. A total of 82 women was evaluated. All women showing hemoglobin less than or equal to 125 g/L were supplemented with ferrous sulfate. Hemoglobin and zinc concentrations remained relatively constant during the whole period, while ferritin and vitamin C tended to decrease. Weight gain during pregnancy tended to compensate for pregestational weight, with no significant differences. The prevalence of nutrition deficiencies was between 60-90% for hemoglobin and ferritin, 15-35% for zinc and 64-88% for vitamin C. The classification according to pregestational BMI and weight gain during pregnancy did not discriminate between those women with low or high concentrations of any of the nutrients evaluated. The results of the present study suggest that a biochemical evaluation of nutritional status should be done systematically during pregnancy to detect specific nutrient deficiencies according to prevalence of specific deficiencies in the studied population, as pregestational BMI and weight gain during pregnancy lack the sensitivity to detect the risk for some of these deficiencies.