Defining Cut-Off Scores of a High Cu/Zn Ratio in Blood Plasma During Early Pregnancy

Background: / Objectives Pregnancy is a state of increased physiological inflammation. The Cu/Zn ratio in general has been associated with inflammation. The current study evaluated a cut-off of the Cu/Zn ratio taking a high CRP as outcome variable and investigated possible associations between a high Cu/Zn ratio and obstetric complications. Methods Using the Receiver Operating Characteristic curve (ROCcurve) technique, an upper cut-off level of the Cu/Zn ratio was evaluated in plasma of 2035 pregnant women with a high CRP (>95th percentile) as outcome test, assessed at 12 weeks of gestation. The occurrence of a high BMI, gestational diabetes (GDM), and high psychological distress in relation to a high Cu/Zn ratio was evaluated using logistic regression analysis (OR; 95% CI). Results ROC analysis showed an area under the curve of 0.81 (95% CI: 0.78 – 0.84) and an upper Cu/Zn ratio cut-off level of 2.55 (sensitivity 64%, specificity 84%). Of the 382 women with a high Cu/Zn ratio, 60-66% showed adequate Cu and Zn levels (between the 10th-90th percentiles). Women with a pre-pregnancy BMI > 30 were three times more likely to present with a high Cu/Zn ratio (OR: 2.97; 95% CI: 2.15-4.13). Compared to 1304 women without any obstetric complication, the 108 women who developed GDM were two times more likely to present with a high Cu/Zn ratio at 12 weeks of gestation (O.R.: 1.9, 95% CI: 1.23 – 3.01). Also, women with a high Cu/Zn ratio were almost twice as likely to report persistently high distress symptom levels throughout gestation (O.R. = 1.9, 95% CI: 1.4-2.6). Conclusions A first trimester high Cu/Zn ratio of 2.55 discerns women at risk for developing GDM and high distress symptom levels throughout gestation.