Associations of maternal serum concentration of iron-related indicators with birth outcomes in Chinese: a pilot prospective cohort study.

BACKGROUND: Previous studies of maternal iron and birth outcomes have been limited to single indicators that do not reflect the comprehensive relationship with birth outcomes. We aimed to investigate the relationship between maternal iron metabolism and neonatal anthropometric indicators using comprehensive iron-related indicators. METHODS: A total of 914 Chinese mother-child dyads were enrolled in this prospective study. Subjects' blood samples were collected at ≤ 14 weeks of gestation. Serum concentrations of iron-related indicators were measured by enzyme-linked immunosorbent assay (ELISA). Femur length was measured by B-ultrasound nearest delivery. Neonatal anthropometric indicators were collected from medical records. RESULTS: After adjustment for potential covariates, higher iron (per one standard deviation, SD increase) was detrimentally associated with - 0.22 mm lower femur length, whereas higher transferrin (per one SD increase) was associated with 0.20 mm higher femur length. Compared with normal subjects (10th-90th percentiles), subjects with extremely high (> 90th percentile) iron concentration were detrimentally associated with lower femur length, birth weight, and chest circumference, and a higher risk of low birth weight, LBW (HR: 3.92, 95%CI: 1.28, 12.0). Subjects with high concentration of soluble transferrin receptor, sTFR and transferrin (> 90th percentile) were associated with higher femur length. Subjects with low concentration of iron and ferritin concentrations (< 10th percentile) were associated with a higher risk of LBW (HR: 4.10, 95%CI: 1.17, 14.3) and macrosomia (HR: 2.79, 95%CI: 1.06, 7.35), respectively. CONCLUSIONS: Maternal iron overload in early pregnancy may be detrimentally associated with neonatal anthropometric indicators and adverse birth outcomes.

Associations of serum concentrations of metal nutrients with postpartum anemia among pregnant Chinese women: A large retrospective cohort study.

Background and Aims: The association between serum concentrations of metal nutrients in pregnancy and postpartum anemia has not been widely studied. This study aimed to determine this association in a large retrospective cohort study. Methods: We included 14,829 Chinese women with singleton pregnancies. Serum concentrations of metals before 28 weeks of gestation, the occurrence of postpartum anemia and other potential covariates were obtained from their laboratory or medical records. Cox regression and restricted cubic spline regression models were used to explore the relationship between serum concentrations of metal nutrients in pregnancy and postpartum anemia. Results: After adjustment for covariates, higher concentrations of iron (Fe), magnesium (Mg) and zinc (Zn) and lower concentrations of copper (Cu) were associated with a lower risk of postpartum anemia. Compared with those whose serum concentrations of metal nutrients were in the bottom quintile (Q1), the hazard ratios (HRs) of those whose serum concentrations of metal nutrients were in the top quintile (Q5) were 0.57 (95% confidence interval (CI): 0.50, 0.64) for Fe, 0.67 (95% CI: 0.60, 0.76) for Mg, 0.82 (95% CI: 0.73, 0.93) for Zn, and 1.44 (95% CI: 1.28, 1.63) for Cu. L-shaped curve relationships were found between increasing concentrations of Fe, Mg, and Zn and incidence of postpartum anemia. Higher serum concentrations of Cu were associated with an increased risk of postpartum anemia. Serum concentrations of Fe in Q5 were associated with a lower risk of postpartum anemia when they coincided with serum concentrations of Mg in Q5, Zn in Q5, or Cu in Q1. Conclusion: Higher serum concentrations of Fe, Mg, and Zn, and lower serum concentrations of Cu were associated with a lower risk of postpartum anemia among pregnant women.

Associations between thyroid function and gestational diabetes mellitus in Chinese pregnant women: a retrospective cohort study.

BACKGROUND: Thyroid function is known to be closely linked with type 2 diabetes, but data on the association between thyroid function and gestational diabetes mellitus (GDM) are inconsistent. METHODS: A total of 2849 pregnant women were included in this retrospective study. Serum concentrations of thyroid indicators (free tetraiodothyronine, FT4; thyroid-stimulating hormone, TSH; and thyroid peroxidase antibody, TPO Ab) were obtained from a clinical laboratory. The presence of GDM were drawn from medical records. The clinical subtypes of thyroid function (euthyroidism, subclinical hypothyroidism, hyperthyroidism, and isolated hypothyroxinemia) were categorized according to the thresholds of the 2.5th/97.5th and 10th/90th percentiles of TSH and FT4 concentrations. A concentration of > 34 IU/L was defined as indicating TPO Ab-positivity. RESULTS: Two hundred and thirty-five (8.25%) of the 2849 women were TPO Ab-positive. Higher serum concentrations of FT4 (top vs. bottom tertiles) was found to be negatively associated with the risk of GDM. The corresponding odds (OR) values (top tertile vs. bottom tertile) were 0.71 [95% confidence interval (CI): 0.54, 0.93]. No significant associations were observed between the extremely 2.5th/97.5th or 10th/90th percentiles of FT4 concentration, TSH concentration, thyroid function subtypes (vs. euthyroidism), TPO Ab-positivity (vs. -negativity), and the GDM risk. The corresponding results remained similar when TPO Ab-positive subjects were excluded. CONCLUSIONS: A negative association with the risk of GDM was observed for the highest FT4 concentrations tertile. No significant associations were found between the TSH concentration, thyroid function subtypes, TPO Ab positivity, and the GDM risk.