Table 2 Maternal presenting race/ethnicity and cesarean birth in healthy, laboring nulliparas (N = 5095)

Presenting Race/Ethnicity

 Black-presenting

Ref

–

Ref

–

 White-presenting

0.66 (0.55- 0.79)

 < 0.001

0.57 (0.45–0.73)

 < 0.001

 Hispanic-presenting

1.04 (0.83- 1.29)

0.761

1.17 (0.88, 1.55)

0.278

Maternal Age

–

–

1.08 (1.06–1.10)

 < 0.001

Gestational Age at Labor Onset

 37—37.6

–

–

0.90 (0.62–1.28)

0.560

 38—38.6

–

–

0.96 (0.73–1.27)

0.797

 39—39.6

–

–

Ref

–

 40—40.6

–

–

1.33 (1.08–1.65)

0.009

 41—41.6

–

–

1.93 (1.50–2.48)

 < 0.001

  > 42.0

–

–

1.37 (0.59–2.92)

0.439

Development of Gestational Diabetes

–

–

1.18 (0.79–1.74)

0.415

Development of Hypertensive Disorder

–

–

1.35 (1.12–1.62)

0.002

Mode of Labor Onset

Spontaneous onset, Augmented

–

–

2.00 (1.50- 2.71)

 < 0.001

Induction of Labor

–

–

3.24 (2.41- 4.43)

 < 0.001

Maternal BMI at Labor Admission

  < 25 kg/m²

–

–

Ref

 25—29.99 kg/m²

–

–

1.48 (1.03–2.19)

0.041

 30—34.99 kg/m²

–

–

2.52 (1.75–3.73)

 < 0.001

 35—39.99 kg/m²

–

–

3.52 (2.38–5.32)

 < 0.001

 ≥ 40 kg/m²

–

–

4.83 (3.22–7.41)

0.002