
Keywords: ترانسکوبالامین; Vitamin B12; Transcobalamin; Placenta; Adolescents95% CI, 95% confidence interval; BMI, body mass index; HoloTC, holotranscobalamin; MMA, methylmalonic acid; NTD, neural tube defect; qPCR, quantitative real-time polymerase chain reaction; RR, risk ratio;