Table 1 Patient demographics, pregnancy, and delivery characteristics.

Maternal age (y)

28.6 (5.5) [29, 25–32]

28.0 (5.1) [28, 24–31]

0.25

BMI (kg/m²)

24.2 (5.0) [23.2, 20.7–28.0]

24.0 (4.7) [23.2, 20.7–26.1]

0.74

Delivery num

2.6 (1.5) [2, 2–3]

1.9 (1.1) [1, 1–3]

 < .0001

Primiparity

37 (25%)

137 (51%)

 < .0001

Smoking

1 (1%)

1 (0.4%)

1

Hb before delivery (g/dl)

10.7 (1.4) [10.3, 9.6–11.9]

11.8 (1.3) [11.9, 11–12.7]

 < .0001

HCT before delivery (%)

32 (4) [32, 29–35]

35 (4) [35, 33–37]

 < .0001

Delivery week

39.1 (1.5) [39.2, 38.2–40.2]

39.4 (1.4) [39.5, 38.4–40.4]

0.03

Hemoglobinopathies

5 (3%)

4 (1%)

0.29

GDM

22 (15%)

29 (11%)

0.26

Pre-GDM

2 (1%)

3 (1%)

1

Chronic HTN

2 (1%)

2 (1%)

0.62

Gestational HTN

9 (6%)

17 (6%)

0.88

Clotting abnormalities

14 (9%)

16 (6%)

0.21

Epidural

50 (33%)

129 (48%)

0.003

Vaginal delivery

144 (95%)

241 (90%)

0.05

Vacuum

7 (5%)

27 (10%)

Labor induction

63 (42%)

123 (46%)

0.41

Prolonged second stage

6 (4%)

20 (7%)

0.16

Shoulder dystocia

2 (1%)

3 (1%)

1

Perineal tear grade

0

117 (77%)

160 (60%)

0.0002

1

20 (13%)

44 (16%)

2

12 (8%)

59 (22%)

3

1 (1%)

5 (2%)

4

1 (1%)

0 (0%)

Episiotomy

8 (5%)

51 (19%)

0.0001

Manual exploration of uterine cavity and cervix

4 (3%)

52 (19%)

 < .0001

Manual lysis of placenta

3 (2%)

14 (5%)

0.11