Table 2.
Labor Process Variables Describing the Sample of 24,729 Vaginal Births and the Composition of Each Labor Phenotype Class and Rate of Postpartum Hemorrhage
| Analytic Samplea | Class 1 Spontaneous: Early Admission |
Class 2 Spontaneous: Active Admission |
Class 3 Induction: Moderate Duration Admission |
Class 4 Spontaneous: Prolonged Second Stage |
Class 5 Induction: Prolonged Complicated Admission |
|
|---|---|---|---|---|---|---|
| Distribution of class membership, n (%) | 24,729 (100) | 11,168 (45.1) | 3077 (12.4) | 7485 (30.3) | 1796 (7.3) | 1203 (4.9) |
| Postpartum hemorrhage rate,b n (%) | 1,167 (4.7) | 420 (3.8) | 120 (3.9) | 341 (4.6) | 143 (8.0) | 143 (11.9) |
| Labor process variables | ||||||
| Spontaneous labor, n (%) | 15,493 (62.6) | 10,902 (97) | 2983 (99) | 0 (0) | 1324 (75) | 284 (24) |
| ≥3 methods needed for labor induction,c n (%) | 882 (5.2) | 0 (0) | 0 (0) | 514 (7) | 51 (3) | 317 (31) |
| Neuroaxial analgesia, n (%) | 20,087 (82.2) | 9488 (85) | 1272 (45) | 6479 (86) | 1700 (96) | 1148 (96) |
| Intrauterine pressure catheter, n (%) | 4770 (19.3) | 1783 (16) | 17 (1) | 1645 (22) | 572 (32) | 753 (62) |
| Artificial rupture of membranes, n (%) | 16,416 (66.4) | 6378 (58) | 1571 (59) | 6577 (89) | 960 (56) | 930 (78) |
| Fever and/or intraamniotic infection, n (%) | 819 (3.3) | 298 (3) | 17 (1) | 64 (1) | 253 (14) | 187 (15) |
| Magnesium sulfate use, n (%) | 404 (1.6) | 124 (1) | 15 (1) | 152 (2) | 31 (2) | 82 (7) |
| Having both episiotomy and lacerations, n (%) | 7925 (32.0) | 3429 (31) | 677 (22) | 2225 (30) | 1072 (60) | 522 (43) |
| Instrument-assisted vaginal birth, n (%) | 2096 (8.5) | 679 (6) | 113 (4) | 475 (6) | 599 (34) | 230 (19) |
| Shoulder dystocia, n (%) | 423 (1.7) | 172 (2) | 19 (1) | 127 (2) | 55 (3) | 50 (4) |
| Admission until birth, mean (SD), h | 9.2 (6.9) | 7.5 (1.6) | 2.8 (2.2) | 10.2 (5.0) | 13.3 (5.2) | 26.2 (13.1) |
| Cervical dilatation on admission, mean (SD), cm | 3.5 (2.1) | 3.5 (1.3) | 7.3 (1.6) | 2.4 (1.2) | 3.0 (1.7) | 1.3 (0.9) |
| Oxytocin duration, mean (SD), h | 3.7 (4.5) | 2.0 (2.5) | 0.3 (1.1) | 4.1 (3.0) | 3.9 (4.2) | 13.1 (8.4) |
| Number of cervical examinations, mean (SD) | 7.5 (3.0) | 7.5 (2.6) | 4.8 (1.6) | 7.5 (2.4) | 9.3 (3.2) | 12.6 (3.9) |
| Full dilation duration, mean (SD), h | 0.8 (0.9) | 0.6 (0.5) | 0.5 (0.6) | 0.5 (0.5) | 2.9 (0.9) | 1.3 (0.9) |
| Third stage of labor, mean (SD), min | 5.4 (3.9) | 5.3 (3.6) | 5.1 (4.2) | 5.1 (3.6) | 6.4 (4.8) | 6.2 (4.5) |
Missing data: duration of admission (n = 102), cervical dilatation on admission (n = 758), duration of oxytocin (n = 433), duration of second stage (n = 2021), number of cervical examinations (n = 489), artificial rupture of membranes (n = 704), instrument-assisted vaginal birth (n = 803), medications for labor induction (n = 121), laceration or episiotomy (n = 1).
Postpartum hemorrhage rate is a composite of diagnosis code from the International Classification of Diseases, Ninth Revision and estimated blood loss over 500 mL on birth record.
Methods and procedures included any of the following within cases coded for induced labor only: artificial rupture of membranes, misoprostol or prostaglandin El agonist, mechanical dilator, prostaglandin E2 agonist synthetic oxytocin.