Evaluation of Plasma Homocysteine, Vitamins B6, B12, Folate and Total Antioxidant Capacity in Women Attending Antenatal Care in Omoku, Rivers State, Nigeria

Background: During pregnancy, maternal one-carbon metabolism undergoes significant adaptation, and biomarkers such as homocysteine, vitamins B6 and B12, folate, and TAC play important roles in DNA methylation and redox homeostasis. Impaired antioxidant defence and elevated homocysteine have been identified as potential risk factors during pregnancy, but comparative data across trimesters are scarce in semi-urban Nigerian communities. Objective: This study evaluated plasma homocysteine, vitamins B6 and B12, folate and TAC in pregnant women across the three trimesters of pregnancy and in non-pregnant controls in Omoku, Rivers State, Nigeria. Methods: In this cross-sectional study, 140 women aged 18-50 years were recruited: 20 non-pregnant controls and 120 pregnant women (40 in the first trimester, 40 in the second trimester, and 40 in the third trimester). Plasma homocysteine, vitamin B6, vitamin B12, folate and TAC were determined by enzyme-linked immunosorbent assay (ELISA). Data were analysed by one-way ANOVA and Pearson correlation analysis using GraphPad Prism 8.0.2, with significance set at p<0.05. Results: Maternal age and blood pressure did not differ significantly across groups (p>0.05), whereas body weight increased significantly with advancing gestation (p=0.0025). Plasma homocysteine differed significantly among groups (p=0.0001), being highest in the first trimester (4.54±1.76 µmol/L) and lowest in the third trimester (2.86±0.50 µmol/L). Folate concentration also differed significantly across groups (p=0.0068), peaking in the second trimester (5.29±0.86 ng/mL). Vitamin B6, vitamin B12 and TAC showed no significant inter-group differences (p>0.05). Homocysteine correlated negatively with vitamin B6 (r=-0.345, p=0.007) and folate (r=-0.410, p=0.001), while folate correlated positively with vitamin B6 (r=0.531, p<0.001) and negatively with systolic blood pressure (r=-0.327, p=0.011). Conclusion: Pregnancy was associated with significant gestational changes in plasma homocysteine and folate concentrations, while vitamin B6, vitamin B12 and total antioxidant capacity remained relatively stable. These findings suggest adaptive changes in one-carbon metabolism during pregnancy without clear evidence of widespread micronutrient deficiency. Routine antenatal micronutrient supplementation and monitoring of relevant biochemical parameters may help support maternal nutritional status and favourable pregnancy outcomes.