A Study On Factors Affecting Iron Status Of Women In Early Pregnancy And Its Association With Adverse Birth Outcomes

Purpose: To investigate the iron status of first-trimester pregnant women.And to explore the affecting factors for iron status at the first trimester,specifically,dietary patterns,ironmetabolism-related single nucleotide polymorphism and diet-gene interaction.Meanwhile,discussing the relation between factors above and adverse birth outcomes including preterm birth and low birth weight.Method: During November to December,2018,women in early pregnancy who established prenatal records at the Shunyi District Maternal and Child Health Hospital,Beijing,were approached to participate.388 participants were accessed for data including demographic and anthropometric characteristics,biomarkers reflecting iron status,food frequency questionnaire,and saliva or oral swab for TMPRSS6 rs4820268 and rs855791 genotyping.Dietary patterns were summarized using the principal component analysis(PCA).The Fisher exact probability test and one-way ANOVA were conducted to access differences in iron status and dietary behaviors among groups.Iron deficiency was defined as serum ferritin(SF)<30 2)/.To analyze the potential risk factors for iron deficiency during the first trimester,baseline data listed above were adopted as independent factors for the cross-sectional logistic regression.To analyze the relation between birth outcome and factors including baseline characteristics,iron status,iron-metabolism-related SNPs,and dietary pattern among pregnant women at the first trimester,in addition to gestational anemia,three adverse birth outcomes including preterm birth,low birth weight(LBW),infant macrosomia were then adopted as dependent variables for the prospective Logistic regression.Results: Among 388 participants eligible for final inclusion,in which(30.9%)were iron deficient.The mean SF concentration was 50.4±35.3 2)/.The incidence of gestational anemia during the entire pregnancy was 22.3%.The incidence of preterm birth,LBW and infant macrosomia were 6.4%,4.1% and 9.5%,respectively.Multiparity was a risk factor for iron deficiency during the first trimester(OR: 4.10,95%CI: 1.87-8.42,P=0.001)and preterm birth(OR: 3.99,95%CI: 1.19-13.36,P=0.025).Age(OR =0.96,95%CI: 0.94-0.97,P<0.001)was a protective factor.For multiparas,taking iron-containing supplements significantly reduced the risk of iron deficiency during the first trimester(OR: 0.23,95%CI: 0.08-0.73,P=0.013).Iron-containing supplements also significantly reduced the risk of gestational anemia(OR: 0.43,95%CI: 0.23-0.81,P=0.009).Among the three dietary patterns,the“balance” pattern(OR: 0.56,95%CI: 0.34-0.92,P=0.022)significantly reduced the risk of iron deficiency during the first trimester in individuals with rs855791 CT genotype.The “high protein and whole grains” pattern showed a marginally protective effect on LBW.The “refined grains” pattern(OR: 1.55,95%CI: 1.03-2.04,P=0.029)was a risk factor for preterm birth.Adequate Hb concentration during the first trimester is not only a protective factor for preterm birth but also a protective factor for LBW among individuals with rs855791 CT(OR: 0.96,95%CI: 0.92-0.99,P=0.020)and CC(OR: 0.95,95%CI: 0.92-0.98,P=0.005)genotype.Transferrin Saturation(TSAT)(OR: 1.06,95%CI: 1.01-1.12,P=0.028)and Serum iron(SI)(OR: 0.97,95%CI: 0.95-0.99,P=0.006)concentrations were risk factors and protective factors for gestational anemia,respectively.Conclusions: The interaction of dietary and TMPRSS6 rs855791 gene polymorphism displayed a significant impact on the iron status of women in early pregnancy.For multiparas,taking iron-containing supplements would significantly reduce the risk to iron deficiency at early pregnancy.Iron-containing supplements also showed a significantly protective effect on gestational anemia.