Cord blood zinc status effects on pregnancy outcomes and its relation with maternal serum zinc levels:a systematic review and meta-analysis

Background The association between maternal and cord blood zinc level and pregnancy outcomes remains uncertain.The present study aims to assess whether maternal blood zinc level represents cord blood zinc level correctly.Methods In this meta-analysis,systematic search was performed in PubMed,Web of Science,and Scopus databases for relevant available English articles which included mean and standard deviation values of cord blood zinc level up to April 2019.For the assessment of the relation between cord blood zinc level and pregnancy outcomes,the pooled standard mean difference with 95%confidence interval(CI)was used and 23 studies were analyzed.Results Cumulative analysis showed that cord blood zinc level was found significantly decreased in pregnancies with complications compared with healthy pregnancy controls[REM:P=0.0007,mean difference−7.9(−12.48,−3.31)].For further analysis,maternal serum zinc level status was determined from same studies to compare with cord blood levels and subgroups were detected as“Preterm”,“Preeclampsia”,“Small for gestational age/Intrauterine growth restriction and Low birth weight”.It was observed that cord blood zinc levels in subgroup analysis were also decreased and/or tend to be decreased compared to healthy pregnancies,except for preeclampsia subgroup.Also,a correlation was seen between cord blood and maternal blood zinc level status(R=0.4365,95%CI−0.530,0.756;P=0.0351).Conclusion It was thought that cord blood zinc level might tend to decrease more than maternal serum zinc level in the pathological conditions during pregnancies.