Table 1 Maternal characteristics and outcomes in pregnancies with either maternal hemoglobin (Hb) < 110 g/l or Hb ≥ 110 g/l. The values given are median (range) or n (%)

Maternal factors

 Age at delivery (years, median(range))

30 (18–45)

30 (17–44)

0.658

 Primiparity, n(%)

155 (52.5%)

612 (64.2%)

 < 0.001*

 Body mass index median(range)

22 (16–45)

23.5 (17–46)

 < 0.001*

 Prior Cesarean delivery, n(%)

21 (7.1%)

55 (5.8%)

0.398

 Pre-pregnancy hypertension*, n(%)

4 (1.8%)

18 (2.3%)

0.799

 Type I diabetes, n(%)

1 (0.4%)

0

 Type II diabetes, n(%)

2 (0.9%)

2 (0.3%)

SSRI/SNRI medication during pregnancy, n(%)

 I trimester

7 (3.1%)

24 (3.0%)

0.985

 III trimester

5 (2.6%)

18 (2.6%)

1.000

Smoking, n(%)

0.016*

 I trimester

31 (10.4%)

99 (10.2%)

 III trimester

30 (10.0%)

55 (5.7%)

Alcohol consumption, n(%)

 I trimester

46 (20.4%)

192 (24.6%)

0.213

 III trimester

22 (11.6%)

75 (10.8%)

0.696

Level of education, n(%)

0.579

 Secondary school

83 (36.2%)

267 (33.4%)

 High school or vocational education

65 (28.4%)

220 (27.5%)

 University or polytechnic degree or higher

81 (35.4%)

312 (39.0%)

Pregnancy

 Hb < 20 weeks, median(range)

122 (86–148)

130 (111–153)

 < 0.001*

 Hb 20–30 weeks, median(range)

108 (91–128)

121 (110–143)

 < 0.001*

 Hb > 30 weeks, median(range)

108 (87–132)

124 (110–149)

 < 0.001*

 Threatening prematurity, n(%)

2 (0.7%)

2 (0.2%)

0.239

 Antenatal corticosteroids, n(%)

11 (3.7%)

18 (1.9%)

0.067

Delivery and postpartum period

 Duration of labor (minutes, median(range))

430 (38–2066)

464 (39–2204)

0.196

 Induction of labor, n(%)

70 (23.7%)

233 (24.5%)

0.794

 Mode of delivery, n(%)

  Vaginal delivery

242 (82.0%)

778 (81.6%)

0.877

  Cesarean section

53 (18.0%)

175 (18.4%)

 Cesarean section urgency

0.931

  Elective

20 (6.8%)

62 (6.5%)

  Emergency

30 (10.2%)

101 (10.6%)

  Crash emergency

3 (1.0%)

12 (1.3%)

 Red blood cell transfusion, n(%)

14 (4.7%)

25 (2.6%)

0.083

Neonatal outcome

 Gestational age at delivery, median(range)

39.9 (33.2–42.2)

40.1 (29.2–42.4)

0.073

 Birth weight (g, median(range))

3634 (1560–4950)

3550 (820–5200)

0.512

 Male, n(%)

147 (49.2%)

500 (51.8%)

0.423

 Umbilical artery pH, median(range)

7.28 (6.99–7.48)

7.27 (6.80–7.54)

0.373

 Umbilical vein pH, median(range)

7.36 (7.11–7.52)

7.35 (6.94–7.52)

0.387

 Neonatal intensive care, n(%)

53 (18.0%)

128 (13.4%)

0.053