Table 2.
Comparison of Demographic, Prenatal, and Intrapartum Risk Factors Between Study Groups Exposed or Not Exposed to Active Management of Risk in Pregnancy at Term (AMOR-IPAT)
| Factor | Exposed (n = 794) | Nonexposed (n = 1,075) | Risk Ratio (95% CI) | P Value |
| Demographic | ||||
| Age, mean, y | 26.0 | 26.7 | – | .005* |
| Advanced age (≥35 y) at delivery, % | 7.7 | 8.7 | 0.92 (0.75–1.13) | .44 |
| Single, % | 34.3 | 28.6 | 1.16 (1.04–1.29) | .008 |
| Private medical insurance, % | 61.7 | 71.4 | 0.78 (0.70–0.87) | <.001 |
| White, % | 98.0 | 97.3 | 1.20 (0.81–1.78) | .36 |
| Family physician practitioner, % | 44.7 | 24.1 | 1.65 (1.49–1.83) | <.001 |
| Prenatal | ||||
| Nulliparous, % | 42.1 | 45.2 | 0.92 (0.83–1.03) | .19 |
| Multiparous, no prior cesarean, % | 51.3 | 46.3 | 1.12 (1.01–1.24) | .04 |
| Multiparous, prior cesarean, % | 6.7 | 8.5 | 0.86 (0.69–1.07) | .16 |
| Late prenatal care (>4th mo), % | 9.7 | 9.6 | 1.01 (0.84–1.20) | .94 |
| Dating ultrasound (12–20 wk), % | 71.8 | 62.5 | 1.28 (1.13–1.45) | <.001 |
| Cigarette use, % | 29.0 | 29.4 | 0.99 (0.88–1.11) | .88 |
| History of hypertension, % | 2.5 | 2.0 | 1.15 (0.84–1.58) | .42 |
| History of asthma, % | 7.8 | 7.3 | 0.96 (0.79–1.19) | .79 |
| Previous cervical surgery, % | 20.6 | 20.9 | 0.99 (0.87–1.13) | .91 |
| Previous assisted (vacuum or forceps) vaginal delivery, % | 3.2 | 2.4 | 1.16 (0.87–1.54) | .39 |
| Previous macrosomia (>4,000 g), % | 0.8 | 1.3 | 0.91 (0.77–1.09) | .37 |
| Previous low birth weight (<2,500 g), % | 1.8 | 2.9 | 0.72 (0.47–1.13) | .13 |
| Short stature (≤62 in), % | 26.1 | 30.0 | 0.89 (0.79–1.01) | .06 |
| High BMI (≥30 kg/m2) at conception, % | 17.5 | 15.5 | 1.08 (0.95–1.24) | .26 |
| Excess weight gain (>30 lb), % | 44.5 | 50.8 | 0.86 (0.78–0.96) | .008 |
| Size greater than dates (≥3 cm), % | 7.6 | 5.4 | 1.21 (1.01–1.46) | .07 |
| Size less than dates (≤3 cm), % | 1.4 | 2.8 | 0.64 (0.41–0.98) | .04 |
| Anemia in first trimester (Hgb <11 g/dL),† % | 6.0 | 3.7 | 1.33 (1.05–1.66) | .03 |
| High glucose (>135 mg/dL) on 50-g glucose test, % | 26.0 | 24.3 | 1.06 (0.91–1.23) | .47 |
| Gestational diabetes, % | 7.4 | 6.9 | 1.04 (0.86–1.28) | .65 |
| Suspected IUGR or oligohydramnios, % | 0.9 | 3.0 | 0.42 (0.21–0.82) | .002 |
| Intrapartum | ||||
| Gestational age on admission (calculated) | 39 wk 5 d | 39 wk 6 d | – | .01* |
| Bishop score on admission, mean | 4.97 | 5.12 | – | .05* |
| Bishop score <6 on admission, % | 55.9 | 50.0 | 1.15 (1.03–1.28) | <.01 |
| PGE2 gel cervical ripening, % | 23.3 | 15.7 | 1.30 (1.15–1.46) | <.001 |
| Ruptured membrane on admission, % | 23.7 | 22.7 | 1.03 (0.91–1.17) | .62 |
| MAP on admission, mean, mm Hg | 93.4 | 94.0 | – | .09* |
| Preeclampsia, % | 3.6 | 3.7 | 0.99 (0.74–1.31) | 1.00 |
| Malpresentation (nonvertex), % | 1.6 | 3.4 | 0.62 (0.39–0.99) | .03 |
| Intrapartum oxytocin use (any), % | 49.5 | 51.6 | 0.95 (0.86–1.06) | .37 |
| Epidural analgesia,‡ % | 6.5 | 15.7 | 0.39 (0.28–0.53) | <.001 |
| Temperature maximum >100.4°F, % | 0.8 | 1.5 | 0.64 (0.32–1.27) | .19 |
| Thick meconium on ROM, % | 1.2 | 3.8 | 0.45 (0.25–0.75) | .001 |
| Elective repeated cesarean, % | 0.9 | 1.2 | 0.82 (0.45–1.50) | .65 |
CI = confidence interval; BMI = body mass index; Hgb = hemoglobin; IUGR = intrauterine growth restriction; PGE2 = prostaglandin E2; MAP = mean arterial pressure; ROM = rupture of membranes.
* Calculated using the Wilcoxon rank-sum test.
† Numerator/denominator were 39/649 in the exposed group and 36/981 in the nonexposed group.
‡ Epidural analgesia during labor, excluding patients given epidural analgesia immediately before cesarean delivery.