Maternal selenium, copper and zinc concentrations in pregnancy associated with small-for-gestational-age infants

Pregnancy during adolescence increases the risk of adverse pregnancy outcome, especially small-for-gestational-age (SGA) birth, which has been linked to micronutrient deficiencies. Smoking has been shown to be related to lower micronutrient concentrations. Different ethnicities have not been examined. We used a subset from a prospective observational study, the About Teenage Eating study consisting of 126 pregnant adolescents (14-18-year-olds) between 28 and 32 weeks gestation. Micronutrient status was assessed by inductively coupled mass spectrometry. Smoking was assessed by self-report and plasma cotinine, and SGA was defined as infants born <10th corrected birthweight centile. The main outcome measures were as follows: (1) maternal plasma selenium, copper and zinc concentrations in adolescent mothers giving birth to SGA vs. appropriate-for-gestational-age (AGA) infants; and (2) comparison of micronutrient concentrations between women of different ethnicities and smoking habits. The plasma selenium {mean±standard deviation (SD) [95% confidence interval (CI)]} concentration was lower in the SGA [n=19: 49.4±7.3 (CI: 45.9, 52.9) μgL^-1] compared with the AGA [n=107: 65.1±12.5 (CI: 62.7, 67.5) μgL^-1; P<0.0001] group. Smoking mothers had a lower selenium concentration compared with non-smokers (P=0.01) and Afro-Caribbean women had higher selenium concentrations compared with White Europeans (P=0.02). Neither copper nor zinc concentrations varied between groups. Low plasma selenium concentration in adolescent mothers could contribute to the risk of delivering an SGA infant, possibly through lowering placental antioxidant defence, thus directly affecting fetal growth. Differences in plasma selenium between ethnicities may relate to variation in nutritional intake, requiring further investigation.