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. 2022 Dec 1;12:20762. doi: 10.1038/s41598-022-23432-1

Table 2.

Unadjusted and multivariate-adjusted linear regression models of the associations between maternal SF and Hb levels (continuous, tertiles) and children’s T-score of CPRS-R:S subscales at age 7 years.

T-score of CPRS-R:S subscales
Oppositional Cognitive Problems/Inattention Hyperactivity ADHD Index
β (95% CI) p value β (95% CI) p value β (95% CI) p value β (95% CI) p value
SF levels (µg/L) at 1st period of gestation (n = 1204)*
Log-SF (per SD, continuous), unadjusted model 0.15 (− 0.41, 0.70) 0.60 0.63 (0.06, 1.19) 0.029 0.37 (− 0.21, 0.95) 0.21 0.72 (0.20, 1.24) 0.007
Log-SF (per SD, continuous), multivariate-adjusted model† 0.33 (− 0.24, 0.91) 0.25 0.47 (− 0.11, 1.05) 0.11 0.26 (− 0.34, 0.85) 0.40 0.50 (− 0.04, 1.04) 0.08

R2 = 0.043, adj.R2 = 0.026,

F (19, 1081) = 2.56, p < 0.001

R2 = 0.076, adj.R2 = 0.060,

F (19, 1081) = 4.70, p < 0.001

R2 = 0.077, adj.R2 = 0.061,

F (19, 1081) = 4.74, p < 0.001

R2 = 0.079, adj.R2 = 0.063,

F (19, 1081) = 4.90, p < 0.001
T1 (< 21.5 μg/L) 0 (Ref.) 0 (Ref.) 0 (Ref.) 0 (Ref.)
T2 (21.5–38 μg/L) 0.51 (− 0.86, 1.88) 0.46 0.21 (− 1.17, 1.59) 0.77 0.94 (− 0.47, 2.35) 0.19 0.29 (− 1.00, 1.57) 0.66
T3 (≥ 38 μg/L) 0.18 (− 1.20, 1.57) 0.79 0.40 (− 1.00, 1.83) 0.57 − 0.09 (− 1.51, 1.33) 0.90 0.46 (− 0.84, 1.76) 0.49
p for trend€ 0.89 0.58 0.69 0.50

R2 = 0.042, adj.R2 = 0.025,

F (20, 1080) = 2.39, p < 0.001

R2 = 0.074, adj.R2 = 0.057,

F (20, 1080) = 4.34, p < 0.001

R2 = 0.078, adj.R2 = 0.061,

F (20, 1080) = 4.60, p < 0.001

R2 = 0.077, adj.R2 = 0.060,

F (20, 1080) = 4.50, p < 0.001
SF levels (µg/L) at 1st trimester (n = 633)
Log-SF ((per SD, continuous), multivariate-adjusted model† − 0.11 (− 0.94, 0.71) 0.79 0.46 (− 0.38, 1.30) 0.28 − 0.08 (− 0.99, 0.84) 0.86 0.54 (− 0.24, 1.32) 0.17

R2 = 0.053, adj.R2 = 0.021,

F (19, 565) = 1.67, p = 0.037

R2 = 0.121, adj.R2 = 0.09,

F (19, 565) = 4–09, p < 0.001

R2 = 0.079, adj.R2 = 0.050,

F (19, 565) = 2.57, p < 0.001

R2 = 0.011, adj.R2 = 0.080,

F (19, 565) = 3.67, p < 0.001
T1 (< 24.2 μg/L) 0 (Ref.) 0 (Ref.) 0 (Ref.) 0 (Ref.)
T2 (24.2–41 μg/L) 0.20 (− 1.70, 2.09) 0.84 0.24 (− 1.67, 2.16) 0.80 1.23 (− 0.85, 3.31) 0.35 0.97 (− 0.81, 2.745 0.29
T3 (≥ 41 μg/L) − 0.84 (− 2.74, 1.05) 0.38 0.28 (− 1.63, 2.19) 0.77 − 1.31 (− 3.39, 0.77) 0.21 0.45 (− 1.33, 2.23) 0.62
p for trend€ 0.32 0.79 0.12 0.75

R2 = 0.055, adj.R2 = 0.022,

F (20, 564) = 1.65, p = 0.037

R2 = 0.121, adj.R2 = 0.09,

F (20, 564) = 3.82, p < 0.001

R2 = 0.090, adj.R2 = 0.056,

F (20, 564) = 2.57, p < 0.001

R2 = 0.011, adj.R2 = 0.077,

F (20, 564) = 3.44, p < 0.001
SF levels (µg/L) at 2nd trimester (n = 571)
Log-SF (per SD), multivariate-adjusted model† 0.57 (− 0.26, 1.40) 0.17 0.50 (− 0.33, 1.32) 0.23 0.50 (− 0.27, 1.28) 0.20 0.43 (− 0.33, 1.20) 0.26

R2 = 0.056, adj.R2 = 0.020,

F (19, 496) = 1.54, p = 0.066

R2 = 0.066, adj.R2 = 0.030,

F (19, 496) = 1.83, p = 0.017

R2 = 0.077, adj.R2 = 0.042,

F (19, 496) = 2.18, p = 0.003

R2 = 0.067, adj.R2 = 0.031,

F (19, 496) = 1.83, p = 0.014
T1 (< 19.3 μg/L) 0 (Ref.) 0 (Ref.) 0 (Ref.) 0 (Ref.)
T2 (19.3–35.7 μg/L) 0.20 (− 1.83, 2.22) 0.85 0.90 (− 1.11, 2.91) 0.38 0.84 (− 1.04, 2.73) 0.38 0.24 (− 1.62, 2.11) 0.80
T3 (≥ 35.7 μg/L) 0.95 (− 1.12, 3.03) 0.37 1.32 (− 0.74, 3.38) 0.21 1.56 (− 0.38, 3.49) 0.11 1.13 (− 0.79, 3.04) 0.25
p for trend€ 0.34 0.24 0.12 0.23

R2 = 0.054, adj.R2 = 0.016,

F (20, 495) = 1.41, p = 0.109

R2 = 0.066, adj.R2 = 0.028,

F (20, 495) = 1.75, p = 0.023

R2 = 0.078, adj.R2 = 0.041,

F (20, 495) = 2.11, p = 0.003

R2 = 0.068, adj.R2 = 0.030,

F (20, 495) = 1.79, p = 0.019
Hb (g/dL) at 1st trimester (n = 1101)
Hb (g/dL, continuous), unadjusted model − 0.34 (− 0.99, 0.32) 0.31 − 0.14 (− 0.81, 0.54) 0.69 − 0.24 (− 0.92, 0.45) 0.50 − 0.05 (− 0.67, 0.57) 0.87
Hb (g/dL, continuous), multivariate-adjusted model† − 0.24 (− 0.89, 0.41) 0.48 − 0.16 (− 0.82, 0.50) 0.63 − 0.29 (− 0.96, 0.38) 0.39 − 0.07 (− 0.68, 0.54) 0.83

R2 = 0.043, adj.R2 = 0.027,

F (19, 1081) = 2.58, p < 0.001

R2 = 0.076, adj.R2 = 0.060,

F (19, 1081) = 4.72, p < 0.001

R2 = 0.080, adj.R2 = 0.061,

F (19, 1081) = 4.71, p < 0.001

R2 = 0.080, adj.R2 = 0.064,

F (19, 1081) = 4.96, p < 0.001
T1 (< 12.5 g/dL) 0 (Ref.) 0 (Ref.) 0 (Ref.) 0 (Ref.)
T2 (12.5–13.3 g/dL) − 0.73 (− 2.08, 0.61) 0.28 − 1.21 (− 2.56, 0.15) 0.08 − 1.13 (− 2.52, 0.26) 0.11 − 0.85 (− 2.11, 0.41) 0.19
T3 (≥ 13.3 g/dL) − 0.49 (− 1.86, 0.88) 0.48 − 0.09 (− 1.47, 1.29) 0.90 − 0.24 (− 1.65, 1.17) 0.74 0.10 (− 1.18, 1.38) 0.88
p for trend€ 0.48 0.90 0.72 0.86

R2 = 0.044, adj.R2 = 0.026,

F (20, 1080) = 2.49, p < 0.001

R2 = 0.080, adj.R2 = 0.063,

F (20, 1081) = 4.689, p < 0.001

R2 = 0.078, adj.R2 = 0.061,

F (20, 1081) = 4.59, p < 0.001

R2 = 0.082, adj.R2 = 0.066,

F (20, 1081) = 4.86, p < 0.001
Hb (g/dL) at 3rd trimester (n = 1129)
Hb (g/dL, continuous), unadjusted model − 0.01 (− 0.62, 0.60) 0.96 − 0.30 (− 0.92, 0.32) 0.34 − 0.31 (− 0.95, 0.33) 0.34 − 0.27 (− 0.85, 0.30) 0.35
Hb (g/dL, continuous), multivariate-adjusted model† − 0.06 (− 0.66, 0.55) 0.86 − 0.26 (− 0.86, 0.35) 0.40 − 0.29 (− 0.92, 0.33) 0.35 − 0.25 (− 0.81, 0.32) 0.39

R2 = 0.041, adj.R2 = 0.025,

F (19, 1109) = 2.50, p < 0.001

R2 = 0.077, adj.R2 = 0.061,

F (19, 1109) = 4.88, p < 0.001

R2 = 0.073, adj.R2 = 0.058,

F (19, 1109) = 4.62, p < 0.001

R2 = 0.078, adj.R2 = 0.062,

F (19, 1109) = 4.91, p < 0.001
T1 (< 11.1 g/dL) 0 (Ref.) 0 (Ref.) 0 (Ref.) 0 (Ref.)
T2 (11.1–12 g/dL) − 0.52 (− 1.86, 0.83) 0.45 − 0.34 (− 1.69, 1.01) 0.62 − 0.42 (− 1.81, 0.97) 0.55 − 0.21 (− 1.47, 1.04) 0.74
T3 (≥ 12 g/dL) 0.18 (− 1.16, 1.53) 0.79 − 0.10 (− 1.44, 1.25) 0.89 − 0.33 (− 1.72, 1.06) 0.64 − 0.18 (− 1.43, 1.08) 0.78
p for trend€ 0.82 0.88 0.63 0.78

R2 = 0.042, adj.R2 = 0.025,

F (20, 1108) = 2.43, p < 0.001

R2 = 0.077, adj.R2 = 0.060,

F (20, 1108) = 4.61, p < 0.001

R2 = 0.073, adj.R2 = 0.056,

F (20, 1108) = 4.36, p < 0.001

R2 = 0.077, adj.R2 = 0.060,

F (20, 1108) = 4.63, p < 0.001

CI confidence interval, SD standard deviation, BMI body mass index, T tertile, SF serum ferritin, Hb haemoglobin, CPRS-R:S Conners’ Parent Rating Scale-Revised Short Form, ADHD attention deficit hyperactivity disorder.

Linear regression models were used to calculate β coefficient (β) and 95% confidence intervals (CIs). Bold values denote a significant statistical test at a level of statistical significance p-value < 0.05. †Models were adjusted for cohorts (Gipuzkoa, Sabadell, Valencia), maternal age (years), maternal pre-pregnancy BMI (kg/m2), social class (low, medium, high), smoking during pregnancy (yes, no), mode of delivery (eutocic, dystocic), parity (primiparous, multiparous) breastfeeding (months), total iron intake above the RDA (27 mg/d) (yes, no), children’s sex (male, female), age at delivery (weeks), birth weight (kg), birth head circumference (cm), children’s age at time of test (years) and BMI-for-age z-score at age 7 years, log-SF levels in 1st period (μg/L) (for Hb analyses) and Hb levels (for SF analyses). €Tests for trend were conducted using the median values for each tertile of SF or Hb as a continuous variable in the multivariate regression models. *SF measurements at first and second trimester as a whole were defined as first period of pregnancy.