Table 2. Maternal characteristics by the starting dose of oxytocin for labor augmentation in nulliparas.
| Starting dose | ||||
|---|---|---|---|---|
| 1 mU/min. N=1319 | 2 mU/min. N=2383 | 4 mU/min N=4073 | P* | |
| Maternal race White (%) | 73 | 48 | 67 | <.0001 |
| Black (%) | 2 | 23 | 7 | |
| Hispanic (%) | 13 | 19 | 16 | |
| Other or unknown (%) | 12 | 10 | 10 | |
| Insurance Private (%) | 79 | 57 | 67 | <.0001 |
| Public (%) | 21 | 43 | 33 | |
| Maternal age (mean ± SD, year) | 25.0 (4.9) | 24.0 (5.3) | 23.9 (4.7) | <.0001 |
| Epidural analgesia (%) | 95 | 84 | 94 | <.0001 |
| Intrauterine pressure catheter use (%) | 46 | 31 | 38 | <.0001 |
| Fetal scalp electrode use (%) | 44 | 41 | 39 | 0.0015 |
| Cervical dilation at admission (mean ± SD, cm) | 2.5 (1.5) | 2.9 (1.5) | 2.6 (1.4) | <.0001 |
| No. of contractions/10 minutes at admission (mean ± SD) | 3.5 (1.2) | 3.1 (1.5) | 3.7 (1.4) | <.0001 |
| Effacement at admission (mean ± SD, %) | 81 (13) | 79 (17) | 80 (14) | <.0001 |
| Station at admission (median, 10th, 90th centiles) | -1 (-2, 0) | -2 (-3, -1) | -2 (-3, 0) | <.0001 |
| Cervical dilation at start of oxytocin | 3 (1, 7) | 4 (1, 8) | 3 (1, 7) | <.0001 |
| Highest dose of oxytocin (mU/min) (median, 10th, 90th centiles) | 7 (2, 19) | 9.5 (2, 24) | 12 (4, 20) | <.0001 |
*
Chi-square test for categorical variables; analysis of variance for continuous variables with a normal distribution; Kruskal-Wallis test for continuous variables with a non-normal distribution.