OBJECTIVETo investigate calcium, iron and magnesium intakes of preterm infants' mothers before and during pregnancy and calcium, iron and magnesium levels of preterm infants and their mothers in order to provide basis for studying the effect of nutritional factors on the occurrence of prematurity.

METHODSTwo hundred and forty matched cases (preterm infants and their mothers) and controls (term infants and their mothers) were recruited. A nutritional survey of calcium, iron and magnesium intakes was performed in the mothers before and during pregnancy. Calcium, iron and magnesium levels in maternal plasma and in cord blood, placenta, breast milk, meconium, and amniotic fluid were measured with axial view inductively coupled plasma optical emission spectrometry (ICP-OES).

RESULTSIron and magnesium intakes in preterm infants' mothers were significantly less than those in term infants' mothers before pregnancy (P<0.05). Iron and calcium intakes in preterm infants' mothers were also significantly less than those in term infants' mothers during pregnancy (P<0.05). Multivariate analysis of variance showed that iron and calcium levels of preterm infants' mothers were significantly lower than those of term infants' mothers (P<0.05). The preterm infants showed significantly lower iron and magnesium levels than term infants (P<0.05). Plasma levels of calcium, iron and magnesium in infants were positively correlated to maternal plasma levels of calcium, iron and magnesium (r=0.517, 0.622, 0.518, respectively; P<0.05).

CONCLUSIONSThe iron and calcium levels of preterm infants' mothers were lower than those of term infants' mothers, and the iron and magnesium levels of preterm infants were lower than those of term infants. The exact relationship between calcium, iron and magnesium levels and intakes before and during pregnancy needs to be explored further.