Gestational age-specific reference intervals for blood copper, zinc, calcium, magnesium, iron, lead, and cadmium during normal pregnancy

• We reported gestational age-specific reference intervals for blood elements.
• We established such reference intervals using nonparametric method.
• Data were obtained from 2380 samples of normal pregnant women.
• 2380 samples were divided into 5 groups according to gestational age.
• Other clinical laboratories use the reference intervals after validation.

ObjectivesThe aim of this study was to investigate the blood copper (Cu), zinc (Zn), calcium (Ca), magnesium (Mg), iron (Fe), lead (Pb), and cadmium (Cd) concentrations in women of ≤ 12 (group I), 13–20 (group II), 21–27 (group III), 28–35 (group IV), and 36–42 (group V) weeks of gestation and compare them with those in nonpregnant women.Design and methodsThe cross-sectional study was performed in 2380 pregnant women [group I (n = 550); group II (n = 552); group III (n = 600); group IV (n = 553); and group V (n = 125)] and 552 nonpregnant women as controls. Blood seven element concentrations, including Cu, Zn, Ca, Mg, Fe, Pd, and Cd, were determined by atomic absorption spectrometry (AAS).ResultsCompared with the nonpregnant women group, the concentrations of Cu, Zn, Ca, Mg, Fe, Pb, and Cd at ≤ 12, 13–20, 21–27, 28–35, and 36–42 weeks of gestation, on the whole, were significantly different. Blood Cu, Mg, Ca, Fe, Pb, and Cd concentrations were correlated with weeks of gestation (P < 0.05). The gestational age-specific reference intervals were established for Cu, Zn, Ca, Mg, Fe, Pd, and Cd.ConclusionsThe established reference intervals for Cu, Zn, Ca, Mg, and Fe can provide important guidance for the reasonable supplementation of essential elements in pregnancy. And the reference intervals for Pd and Cd can play an important part in the surveillance and diagnosis of environmental overexposure.