TABLE 1.
Demographic and clinical sample characteristics of 4057 nulliparous women in two tertiary care academic nurse-midwifery practices
| Variable | Sample | Michigan | Oregon | P-value |
|---|---|---|---|---|
| Total n | 4057 | 2803 | 1253 | |
| Maternal age | 0.000 | |||
| Mean (SD) | 28.9 (5.3) | 28.3 (5.4) | 30.0 (5.0) | |
| ≥35 y | 643 (16.9) | 291 (10.5) | 227 (18.9) | |
| Race/ethnicity | <0.001 | |||
| White | 3188 (80.2) | 2093 (76.1) | 1096 (89.2) | |
| Black | 350 | 325 (11.8) | 25 (2.0) | |
| Hispanic/Latina | 219 | 108 (3.92) | 111 (9.0) | |
| Asian | 193 | 123 (4.5) | 70 (5.6) | |
| Native American/Alaska Native | 14 | 9 (0.3) | 5 (0.4) | |
| Native Hawaiian or Pacific Islander | 10 | n/a | 10 (0.8) | |
| Middle Eastern | 88 | 88 (3.2) | n/a | |
| Identified by two or more/other | 26 | 3 (0.1) | 23 (1.9) | |
| Pre-pregnancy BMI | ||||
| Normal | 2038 (55.9) | 1251 (52.0) | 787 (63.5) | <0.001 |
| Underweight | 126 (3.5) | 83 (3.5) | 43 (3.5) | |
| Overweight | 920 (25.2) | 658 (27.3) | 262 (21.2) | |
| Obese | 561 (15.4) | 413 (17.2) | 148 (12.0) | |
| Gestational age at birth (weeks +days) | ||||
| 37 + 0–37 + 6 | 175 (4.3) | 122 (4.4) | 53 (4.2) | |
| 38 + 0–38 + 6 | 430 (10.6) | 317 (11.3) | 113 (9.0) | |
| 39 + 0–39 + 6 | 988 (24.4) | 721 (25.7) | 267 (21.3) | |
| 40 + 0–40 + 6 | 1303 (32.2) | 887 (31.7) | 416 (33.2) | <0.001 |
| 41 + 0–41 + 6 | 962 (23.7) | 632 (22.6) | 330 (26.3) | |
| 42 + weeks | 199 (4.9) | 124 (4.4) | 75 (5.9) | |
| Delivery year | ||||
| 2007–2011 | 1007 | 1007 | 0 | <0.001 |
| 2012–2018 | 3050 | 1796 | 1254 | |
| Reasons for labor induction | 0.39 | |||
| Labor induction | 1172 (28.9) | 821 (29.3) | 351 (27.9) | |
| Prelabor rupture of membranes | 246 (20.9) | 151 (18.3) | 95 (27.1) | |
| Elective postdates | 205 (17.5) | 168 (20.4) | 37 (10.5) | |
| Medical or obstetric risks/conditions | 531 (45.3) | 364 (44.3) | 167 (47.6) | |
| Social/other elective | 46 (3.4) | 30 (3.6) | 16 (4.5) | |
| Advanced maternal age | 32 (2.7) | n/a | 32 (9.1) | |
| Augmentation (spontaneous labors) | 1087 (37.6) | 704 (35.3) | 383 (42.8) | <0.001 |
| Neuroaxial analgesia | 2118 (60.1) | 1405 (61.8) | 712 (57.0) | 0.006 |
| Hydrotherapy | 2032 (54.9) | 1414 (57.3) | 618 (50.1) | <0.001 |
| Intra-amniotic infection | 197 (6.3) | 94 (5.1) | 103 (8.2) | <0.001 |
| Hypertensive disorder | 352 (8.8) | 233 (8.4) | 119 (9.5) | 0.26 |
| Cesarean birth | 787 (19.4) | 558 (19.9) | 229 (18.3) | 0.22 |
| Instrument-assisted vaginal birth | 136 (3.9) | 81 (3.6) | 55 (5.4) | 0.25 |
| 3rd/4th-degree perineal laceration | 214 (6.5) | 133 (5.9) | 81 (7.9) | 0.03 |
| Episiotomy | 146 (4.5) | 82 (3.7) | 64 (6.1) | 0.002 |
| Postpartum hemorrhage (>/=1000 mL) | 316 (8.5) | 204 (8.3) | 112 (8.9) | 0.46 |
| Vaginal birth | 100 (3.2) | 45 (2.1) | 55 (5.4) | |
| Cesarean birth | 216 (39.9) | 159 (48.2) | 57 (25.3) | |
| Blood transfusion | 44 (1.2) | 14 (0.6) | 30 (2.4) | <0.001 |
| Infant weight, mean(SD), grams | 3463.6 (448.7) | 3454.2 (453.4) | 3484.34 (437.5) | 0.04 |
| Macrosomia (>/=4000 g) | 507 (12.5) | 363 (13.0) | 144 (11.5) | 0.19 |
| 5-minute APGAR <7 | 94 (2.3) | 61 (2.2) | 33 (2.6) | 0.37 |
| Neonatal composite outcome (any of the following outcomes) | 190 (4.7) | 71 (2.5) | 119 (9.5) | <0.001 |
| NICU Admissiona | 181 (4.5) | 64 (2.3) | 117 (9.4) | <0.001 |
| Meconium aspiration | 19 (0.5) | 10 (0.4) | 9 (0.7) | 0.19 |
| Stillbirth or perinatal death | 5 (0.1) | 3 (0.1) | 2 (0.2) | 0.66 |
a
NICU admission also includes protocol-driven observation periods at Oregon site with return to general recovery after 4 h.