Mineral and trace elements in meconium: Comparison in dizygotic twin pairs

It has not been determined whether the concentration of essential elements in the meconium of dizygotic twins is indistinguishable or is related to bi rth weight or placental size differences. We hypothesized that dizygotic tw ins of discordant size would have a dissimilar concentration of essential e lements in the meconium, whereas concordant twins would not exhibit such a difference. We also hypothesized that the smaller the infant/placental weig ht ratio, the greater the concentration of essential elements in meconium. This study was aimed at verifying these hypotheses. Twenty-six pairs of diz ygotic twins, regardless of sex, were divided into two groups separated by the median value of weight discrepancy (13.1%) into concordant (CC) less th an or equal to 13.1% and discordant (DC) > 13.1%. The concentrations of sev en essential elements (calcium, magnesium, phosphorus, copper, zinc, iron, and manganese) were measured in the meconium. Total placental weights for a ll twins were also correlated with infant weights and meconium element conc entration. Heavy/light birth weight ratio of the DC, but not of CC twins, c orresponded to a meconium concentration ratio >1 for calcium, magnesium, ir on, zinc, and manganese, but not for phosphorus and copper. There was a str ong correlation between total twin weight and total placental weight for bo th the CC and DC groups. However, infant/placental weight ratio did not cor relate with meconium element concentration. It may be inferred that in dizy gotic twins, a higher essential element concentration in meconium may refle ct the greater access of the heavier fetus to maternally supplied nutrients , or a different functional capacity of the,gastrointestinal tract. J. Trac e Elem. Exp. Med. 13:205-213, 2000. (C) 2000 Wiley-Liss, Inc.