The effect of parity and time between pregnancies on maternal hair chromium concentration.

Values for hair chromium concentration of nulliparous women and parous women who had just given birth to a child were determined by atomic absorption spectrophotometry. Mean values for hair chromium concentration of nulliparous and parous subjects were 309 +/- 23 and 117 +/- 10 ppb, respectively. The difference was highly significant (P less than 0.001). No further significant decrease in hair chromium was observed in women who had borne more than one child. Hair chromium concentration increased significantly with the amount of time between pregnancies, especially when at least 4 years had passed since the end of the last pregnancy (P less than 0.001). These data suggest a state of suboptimal chromium nutrition during pregnancy.