Assessment of maternal-fetal status of some essential trace elements in pregnant women in late gestation: relationship with birth weight and placental weight.

OBJECTIVE: The status of the essential trace elements copper (Cu), iron (Fe), zinc (Zn), selenium (Se) and molybdenum (Mo) has been investigated in maternal and umbilical cord blood in control, uncomplicated pregnancies at term, and the possibility assessed of a relationship between blood levels of these trace elements and newborn weight and placental weight. Fetal-maternal ratios of the elements were also computed to establish baseline values for the Kuwaiti obstetric population. METHODS: Blood samples were collected from a maternal vein, the umbilical artery and umbilical vein of normal pregnant women at the time of spontaneous delivery or Cesarean section, and the concentrations of various trace elements determined by atomic absorption spectrophotometry. RESULTS: The concentration of Cu, Fe, Mo, Se and Zn averaged 2406.1, 3252.1, 11.6, 107.3 and 696.2 microg/l, respectively, in maternal venous blood in the pregnant women (n=39) at term. Umbilical venous/maternal venous ratios of Cu, Fe, Mo, Se and Zn averaged 0.32, 1.96, 1.03, 0.83 and 1.55, respectively. Neonatal birth weight did not correlate with maternal blood levels of the trace elements (p>0.05) in the mother-child pairs studied. However, neonatal weight correlated negatively (p<0.05) with umbilical venous Cu level. Placental weight correlated positively (p<0.05) with Fe and Mo levels and negatively with Zn level in umbilical venous blood. CONCLUSIONS: Our results indicate an active placental transport for Fe and Zn, while Cu, Mo and Se appear to be exchanged passively between mother and fetus. Evaluation of Fe, Mo, Se and Zn levels in maternal and umbilical cord blood does not appear to be useful in the assessment of fetal growth.