Table 3.

Risk for Postpartum Hemorrhage by Labor Process Phenotype and Maternal and Fetal Characteristics

	Risk for Postpartum Hemorrhage
	Entire Sample (N = 24,729)		Women with Labor Induction (n = 8223) Adjusteda OR (95% CI)
	UnadjustedOR (95% CI)	Adjusteda OR (95% CI)
Labor process phenotype
Class 1 (Spontaneous: Early Admission)	Reference	Reference	Reference
Class 2 (Spontaneous: Active Admission)	1.03 (0.84-1.27)	1.17 (0.93-1.46)	—
Class 3 (Induction: Moderate Duration Admission)	1.22 (1.05-1.42)b	1.26 (1.07-1.47)b	1.56 (0.79-3.11)
Class 4 (Spontaneous: Prolonged Second Stage)	2.21 (1.82-2.70)c	1.77 (1.42-2.21)c	2.63 (1.23-5.60)b
Class 5 (Induction: Prolonged Complicated Admission)	3.45 (2.82-4.21)c	2.82 (2.24-3.54)c	3.89 (1.91-7.89)c
Parity
Nulliparous	1.72 (1.52-1.94)c	1.52 (1.30-1.77)c	1.47 (1.17-1.87)c
Para 1-3	Reference	Reference	Reference
Para 4+	0.72 (0.52-0.99)b	0.69 (0.49-0.99)b	0.62 (0.34-1.11)
Pregnancy weight gain guidelinesd
Met guidelines	Reference	Reference	Reference
Over guidelines	1.34 (1.17-1.54)c	1.22 (1.05-1.43)b	1.18 (0.93-1.49)
Race and ethnicity
White and non-Hispanic	Reference	Reference	Reference
Black and non-Hispanic	1.38 (1.16-1.64)c	1.39 (1.13-1.73)b	1.61 (1.18-2.19)b
Hispanic	1.77 (1.53-2.06)c	1.85 (1.56-2.20)c	1.96 (1.48-2.59)c
Asian or Pacific Islander	1.21 (0.89-1.62)	1.22 (0.89-1.67)	1.58 (0.98-2.57)
Hypertension	2.15 (1.79-2.56)c	1.63 (1.33-2.00)c	1.72 (1.31-2.26)c
Macrosomia (≥4000 g)	1.53 (1.25-1.87)c	1.54 (1.23-1.94)c	1.50 (0.80-1.67)
Indication IOL (n = 9236) elective	0.65 (0.54-0.78)c	NA	1.04 (0.82-1.31)

Abbreviations: IOL, induction of labor; NA, not analyzed; OR, odds ratio.

^aAdjusted for history of prior cesarean birth, fetal sex, prenatal depression, gestational weight gain under recommended guidelines, public versus private insurance, maternal age, smoking status, gestational age at birth, and prepregnancy body mass index.

^bP ≤ .01.

^cP ≤ .001.

^dInstitute of Medicine guidelines based on prepregnancy body mass index.