Plasma concentrations of calcium, chromium, copper, iron, magnesium, and zinc in maternal and cord blood and their relationship to low birth weight.

A study of the relationship between low birth weight and concentrations of six metals in maternal and cord plasma was conducted. Maternal and cord blood were collected at delivery. Cases and controls were matched for maternal age (+/- 3 yr), race, parity, socioeconomic status, and smoking habits and the sex of the neonate. Plasma concentrations of calcium, copper, magnesium, and zinc were determined by flame atomic absorption spectrophotometry; plasma chromium and iron concentrations were determined by flameless atomic absorption techniques. Mean maternal plasma concentrations were significantly lower in the low-birth-weight group than in the controls for iron (p = 0.012) and calcium (p = 0.007). Mean cord plasma concentrations were also significantly lower for calcium (p = 0.037). There were no statistically significant differences between the low- and normal-birth-weight groups for the maternal or cord chromium, copper, magnesium, and zinc concentrations or for the cord iron concentrations. It is probably true that many factors, acting additively or synergistically, can produce low birth weight, and that low birth weight acts only as a marker for a number of biologic insults. The results of this study suggest that nutrient metals may be one of these factors.