Objective: Pregnant adolescents have very high zinc (Zn) requirements to support the developing fetus and to maintain skeletal maturation after menarche.
Methods: Sixty-six adolescents aged 17.1 +/- 0.15 years (mean +/- SEM; range 14.5-19.0 years) were recruited from three regions of Southern Ontario at 35.9 +/- 0.15 weeks gestation. Data on sociodemographic status, health, infant birth weight and birth length, smoking, alcohol consumption, and prenatal supplement use were collected. Fasting venipuncture blood was analyzed for Zn (via AAS) and alkaline phosphatase in plasma; scalp hair was analyzed for Zn by instrumental neutron activation.
Results: Mean (95% CI) values were: plasma Zn 10.7 (10.0-11.5) mumol/L; plasma alkaline phosphatase 46.6 (43.7-49.5) U/L; hair Zn 2.64 (2.52-2.77) mumol/g. None of the plasma and hair Zn values were indicative of suboptimal Zn status. Mean plasma Zn concentrations of subjects (n = 19) consuming a supplement with Zn sulfate were higher than those of subjects consuming a supplement with Zn oxide (n = 18) (12.2 vs 9.7 mumol/L; p < 0.02) and unsupplemented subjects (n = 11) (9.4 mumol/L). Plasma Zn concentrations correlated negatively with reported birth lengths (mean +/- SEM = 51.6 +/- 0.31 cm) while accounting for chronological age (r = 0.42; p < 0.01), but not with reported birth weights (mean +/- SEM = 3.439 +/- 0.107 kg).
Conclusions: Results emphasize that the form of Zn must be taken into account when considering the impact of prenatal supplements containing Zn on plasma Zn concentrations. Suboptimal Zn status was not prevalent in these pregnant adolescents.