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Table 1 Baseline characteristics of the total sample population and subgroups stratified by hemoglobin ranges

From: Hemoglobin levels during the first trimester of pregnancy are associated with the risk of gestational diabetes mellitus, pre-eclampsia and preterm birth in Chinese women: a retrospective study

  Total n = 21,577 Hb <  110 g/L n = 584 110 g/L ≤ Hb < 130 g/L n = 9397 130 g/L ≤ Hb < 150 g/L n = 11,268 Hb ≥ 150 g/L n = 328 p-value
Age (years) 29.8 ± 3.9 29.6 ± 4.3 29.7 ± 4.0 29.9 ± 3.7 30.1 ± 4.3 0.005
Pre-pregnancy BMI (kg/m2) 21.4 ± 3.3 20.5 ± 4.8 21.0 ± 3.1 21.8 ± 3.4 22.8 ± 4.3 < 0.001
Overweight/Obesity 3783 (17.5) 56 (9.6) 1232 (13.1) 2392 (21.2) 103 (31.4) < 0.001
Underweight 3330 (14.4) 129 (22.1) 1720 (18.3) 1452 (12.9) 29 (8.8) < 0.001
Education level (school years) > 12 17,358 (80.4) 399 (68.3) 7358 (78.3) 9341 (82.9) 260 (79.4) < 0.001
Average monthly income       < 0.001
 ≥ 5000 8713 (40.4) 255 (43.6) 3787 (40.3) 4552 (40.4) 119 (36.4)  
 3000–4999 4287 (19.9) 155 (26.5) 1983 (21.1) 2085 (18.5) 64 (19.4)  
 1000–2999 3238 (15.0) 62 (10.7) 1278 (13.6) 1837 (16.3) 61 (18.5)  
 < 1000 5339 (24.7) 112 (19.2) 2349 (25.0) 2794 (24.8) 84 (25.7)  
Parity (nulliparous) 12,409 (57.5) 215 (36.9) 4792 (51.0) 7166 (63.6) 236 (71.9) < 0.001
Family history of DM 2376 (11.0) 27 (4.9) 818 (8.7) 1487 (13.2) 44 (13.5) < 0.001
Hb levels (g/L) 129.9 ± 9.8 103.2 ± 5.9 122.8 ± 4.9 136.4 ± 4.8 153.9 ± 5.2 < 0.001
  1. Data are represented as the mean ± SD or n (%). The p-values refer to the overall differences across the Hb groups as derived from ANOVA (for continuous variables) or χ2 tests (for categorical variables)
  2. Abbreviations: Hb hemoglobin, BMI body mass index