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Table 1 Characteristics of mothers and newborns according to different criteria of maternal ID

From: Iron deficiency in late pregnancy and its associations with birth outcomes in Chinese pregnant women: a retrospective cohort study

 

Serum ferritin (< 12 μg/L)

Serum transferrin (> 4 g/L)

Transferrin/ferritin ratio log10 transform (> 5.52)

Deficient (N = 5995)

Replete (N = 5574)

Deficient (N = 6301)

Replete (N = 5275)

Deficient (N = 6233)

Replete (N = 5331)

Maternal characteristics

 Maternal age at delivery (years)

28 (25–31)**

28 (26–31)

28 (25–31)**

28 (26–31)

28 (25–31)**

28 (26–32)

 ≤ 25 [N(%)]

1558 (25.99%)**

1168 (20.95%)

1577 (25.03%)**

1153 (21.86%)

1604 (25.73%)**

1122 (21.05%)

 26–29 [N(%)]

2461 (41.05%)

2401 (43.07%)

2633 (41.79%)

2227 (42.22%)

2576 (41.33%)

2282 (42.81%)

 ≥ 30 [N(%)]

1976 (32.96%)**

2005 (35.97%)

2091 (33.19%)**

1895 (35.92%)

2053 (32.94%)**

1927 (36.15%)

 BMI at delivery (kg/m2)

26.95 (25–29.30)

26.95 (24.98–29.38)

26.95 (24.97–29.30)

26.99 (25–29.36)

26.99 (25–29.30)

26.95 (24.97–29.36)

 < 25 [N(%)]

1461 (24.65%)

1399 (25.32%)

1600 (25.63%)

1262 (24.19%)

1512 (24.53%)

1347 (25.49%)

 ≥25 [N(%)]

4467 (75.35%)

4126 (74.68%)

4643 (74.37%)

3955 (75.81%)

4652 (75.47%)

3937 (74.51%)

Gravidity

 < 3 [N(%)]

4138 (69.02%)**

4086 (73.30%)

4403 (69.88%)**

3825 (72.51%)

4306 (69.08%)**

3914 (73.42%)

 ≥3 [N(%)]

1857 (30.98%)**

1488 (26.70%)

1898 (30.12%)**

1450 (27.49%)

1927 (30.92%)**

1417 (26.58%)

Parity

 No child [N(%)]

3309 (55.20%)**

3638 (65.27%)

3629 (57.59%)**

3321 (62.96%)

3454 (55.41%)**

3489 (65.45%)

 ≥1 child [N(%)]

2686 (44.80%)**

1936 (34.73%)

2672 (42.41%)**

1954 (37.04%)

2779 (44.59%)**

1842 (34.55%)

 Gestational age at delivery (week)

38.72 ± 1.62

38.66 ± 1.72

38.76 ± 1.54*

38.61 ± 1.81

38.73 ± 1.60

38.65 ± 1.74

 Systolic BP at delivery (mmHg)

120 (110–129)**

120 (110–130)

120 (110–129)**

120 (110–130)

120 (110–129)**

120 (110–130)

 Diastolic BP at delivery(mmHg)

72 (70–79)**

73 (70–80)

72 (70–80)**

73 (70–80)

72 (70–79)**

73 (70–80)

Delivery mode

 Vaginal delivery

3412 (56.91%)

2951 (52.94%)

3573 (56.71%)

3081 (58.41%)

3529 (56.62%)

3122 (58.56%)

 Cesarean section

2583 (43.09%)

2334 (41.87%)

2728 (43.29%)

2194 (41.59%)

2704 (43.38%)

2209 (41.44%)

 Inflammation (hsCRP > 5 mg/L)

1329 (22.17%)**

1639 (29.4%)

1465 (23.25%)**

1507 (28.57%)

1394 (22.36%)**

1572 (29.49%)

 Anemia (hemoglobin < 110 g/L)

2032 (33.89%)**

396 (7.1%)

1735 (27.54%)**

692 (13.12%)

2070 (33.21%)**

356 (6.85%)

 GDM

389 (6.49%)**

580 (10.41%)

539 (8.55%)

429 (8.13%)

429 (6.88%)**

539 (10.11%)

 ICP

301 (5.02%)**

415 (7.45%)

448 (7.11%)**

268 (5.08%)

333 (5.34%)**

383 (7.18%)

 PE

147 (2.45%)**

249 (4.47%)

190 (3.02%)*

208 (3.94%)

163 (2.62%)**

233 (4.37%)

 PIH

107 (1.78%)**

139 (2.49%)

133 (2.11%)

113 (2.14%)

114 (1.83%)**

132 (2.48%)

 PTB

383 (6.39%)*

411 (7.37%)

365 (5.79%)**

432 (8.19%)

389 (6.24%)**

404 (7.58%)

Newborn characteristics

 Sex

  Female

2829 (47.19%)

2623 (47.06%)

2984 (47.36%)

2473 (46.88%)

2985 (47.89%)

2465 (46.24%)

  Male

3166 (52.81%)

2951 (52.94%)

3317 (52.64%)

2802 (53.12%)

3248 (52.11%)

2866 (53.76%)

Birth length (cm)

49.88 ± 1.30**

49.74 ± 1.55

49.91 ± 1.22**

49.70 ± 1.64

49.89 ± 1.28**

49.72 ± 1.58

Birth weight (g)

3390 (3110–3680)**

3320 (3030–3610)

3380 (3100–3680)**

3320 (3020–3600)

3390 (3100–3680)**

3320 (3030–3600)

 < 2500

213 (3.55%)**

304 (5.45%)

209 (3.32%)**

310 (5.88%)

211 (3.39%)**

306 (5.74%)

 2500–4000

5276 (88.01%)

4923 (88.32%)

5544 (87.99%)

4660 (88.34%)

5484 (87.98%)

4710 (88.35%)

 > 4000

506 (8.44%)**

347 (6.23%)

548 (8.70%)**

305 (5.78%)

538 (8.63%)**

315 (5.91%)

Weight for gestational age

 SGA

428 (7.14%)**

595 (10.67%)

480 (7.62%)**

544 (10.31%)

440 (7.06%)**

583 (10.94%)

 AGA

4538 (75.70%)

4217 (75.65%)

4714 (74.81%)

4045 (76.68%)

4705 (75.49%)

4045 (75.88%)

 LGA

1029 (17.16%)**

762 (13.67%)

1107 (17.57%)**

686 (13.00%)

1088 (17.46%)**

703 (13.19%)

  1. Data were presented as median (IQR), mean ± SD and N (%) for continuous variables with normal distribution, continuous variables with skewed distribution, and categorical variables, respectively. *p < 0.05, **p < 0.01, according to Mann-Whitney test for skewed-distributed continuous variables, Student’s t-test for normally-distributed continuous variables, and Chi-square test for categorical variables
  2. Abbreviations: IQR interquartile range, SD standard deviation, BMI body mass index, BP blood pressure, hsCRP high sensitivity C-reactive protein, GDM gestational diabetes mellitus, ICP intrahepatic cholestasis of pregnancy, PE Preeclampsia, PIH pregnancy-induced hypertension, PTB pre-term birth, SGA/AGA/LGA small/appropriate/large for gestational age