Article Figures & Data
Tables
- Table 1.
Practitioner Characteristics by Study Group Exposure to Active Management of Risk in Pregnancy at Term (AMOR-IPAT)
Practitioner Specialty* Number of Deliveries† Overall Induction Rate, % Preventive Induction Rate, % PGE2Use Rate, % Attendance Rate,‡% PGE2 = prostaglandin E2. Notes: Number of deliveries and practitioner rates of labor induction (all types), preventive labor induction, PGE2 usage, and attendance at continuity delivery. * All obstetricians and no family physicians or certified nurse-midwives had cesarean delivery privileges at the study hospital. † Total N = 1,869 deliveries. ‡ The percentage of labors the practitioner attended; 21 patients did not have information concerning delivering physician. § This large obstetrics group had 7 practitioners and shared both prenatal care and deliveries. The composition of this group—practitioner type (number of deliveries)—was obstetrician (256), obstetrician (132), obstetrician (12), certified nurse-midwife (143), obstetrician (3), certified nurse-midwife (2), and obstetrician (36). Exposed group (n = 794 deliveries) Family physician 1 104 50.0 38.5 40.4 91.3 Family physician 2 80 35.4 15.8 24.4 95.1 Family physician 3 91 38.5 19.8 27.5 95.6 Obstetrician 1 438 29.0 17.1 20.8 90.8 Family physician 4 79 25.3 15.2 21.5 91.1 Nonexposed group (n = 1,075 deliveries) Obestritician 2 231 28.1 10.8 10.4 90.8 Family physician 5 49 20.4 16.3 10.2 87.5 Family physician 6 75 18.7 9.3 21.3 96.0 Family physician 7 136 19.8 7.4 16.2 94.0 Obstetrics group§ 584 18.8 5.1 18.2 97.7 - 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 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. 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 - Table 3.
Labor Induction and Cesarean Delivery: Rates and Indications in Study Groups Exposed or Not Exposed to Active Management of Risk in Pregnancy at Term (AMOR-IPAT)
Measure Exposed (n = 794) Nonexposed (n = 1,075) Risk Ratio (95% CI) P Value CI = confidence interval; ACOG = American College of Obstetricians and Gynecologists; CPD = cephalopelvic disproportion. Note: Values in the Exposed and Nonexposed columns are expressed as percent alone or percent (numerator/denominator). Statistical analyses were performed using χ2 tests (Fisher’s exact test). * No “other” reason for cesarean occurred more than twice in either group. Induction rates Overall induction 31.4 20.4 1.37 (1.23–1.52) <.001 Preventive induction 21.2 8.1 1.70 (1.53–1.89) <.001 Indicated induction 10.2 12.3 0.88 (0.74–1.06) .18 Nulliparous induction 27.8 (93/334) 20.6 (100/486) 1.25 (1.05–1.50) .02 Multiparous induction 31.7 (129/407) 19.3 (96/498) 1.40 (1.21–1.62) <.001 Previous cesarean induction 50.9 (27/53) 25.3 (23/91) 1.95 (1.29–2.96) .002 Induction indications ACOG-approved indication Postdates 41–42 wk 5.5 6.0 0.96 (0.76–1.21) .76 Postdates >42 wk 0.3 0.5 0.67 (0.21–2.17) .71 Preeclampsia 1.9 3.0 0.75 (0.49–1.14) .18 Fetal compromise 1.4 1.5 0.96 (0.61–1.52) 1.00 History of rapid labor 0.5 0.4 1.18 (0.59–2.36) .73 Other 0.6 0.9 0.78 (0.38–1.61) .60 Preventive Impending macrosomia 7.2 2.4 1.66 (1.42–1.94) <.001 Previous cesarean delivery 2.4 0.7 1.67 (1.30–2.15) .005 Impending preeclampsia 1.4 0.4 1.74 (1.27–2.37) .02 Gestational diabetes 0.6 0.6 1.07 (0.56–2.05) 1.00 Other 9.6 4.0 1.56 (1.34–1.80) <.001 Cesarean delivery rates Overall cesarean delivery 5.3 11.8 0.56 (0.43–0.73) <.001 Nulliparous – overall 8.1 (27/334) 14.2 (69/486) 0.66 (0.48–0.92) .008 Noninduced labor 7.1 (17/238) 6.8 (25/368) 1.03 (0.71–1.51) .87 Induced labor 7.5 (7/93) 26.0 (26/100) 0.39 (0.20–0.77) <.001 Planned cesarean delivery 100 (3/3) 100 (18/18) – Multiparous – overall 1.2 (5/407) 4.2 (21/498) 0.42 (0.19–0.93) .008 Noninduced labor 1.1 (3/276) 1.8 (7/398) 0.73 (0.28–1.89) .54 Induced labor 0.0 (0/129) 10.4 (10/96) 0 .001 Planned cesarean delivery 100 (2/2) 100 (4/4) – – Previous cesarean delivery – overall 18.9 (10/53) 40.7 (37/91) 0.48 (0.27–0.87) .01 Noninduced labor 5.3 (1/19) 32.7 (18/55) 0.16 (0.02–1.12) .03 Induced labor 7.4 (2/27) 26.1 (6/23) 0.42 (0.12–1.43) .12 Elective repeated cesarean delivery 100 (7/7) 100 (13/13) – – Cesarean delivery indications CPD/failure to progress 2.0 (16/794) 4.7 (51/1,075) 0.55 (0.36–0.85) .001 Fetal intolerance 0.9 (7/794) 2.7 (29/1,075) 0.45 (0.23–0.88) .006 Malpresentation (nonvertex) 1.3 (10/794) 2.6 (28/1,075) 0.61 (0.36–1.05) .05 Elective repeated 0.9 (7/794) 1.2 (13/1,075) 0.82 (0.45–1.50) .65 Other* 0.3 (2/794) 0.6 (6/1,075) 0.59 (0.18–1.95) .48 Univariate Multivariate Variable Odds Ratio 95% CI Odds Ratio 95% CI 95% CI* CI = confidence interval; AMOR-IPAT = Active Management of Risk in Pregnancy at Term; BMI = body mass index. * Adjusted for clustering of births by prenatal care practitioner. AMOR-IPAT exposure 0.42 0.29–0.60 0.56 0.37–0.88 0.37–0.88 Family physician practitioner 0.41 0.27–0.62 0.55 0.34–0.91 0.35–0.87 Short stature (≤62 in) 1.85 1.34–2.57 1.88 1.27–2.78 1.52–2.32 High BMI (>30 kg/m2) at conception 2.07 1.44–2.98 2.43 1.55–3.81 1.64–3.60 Epidural analgesia 4.72 3.25–6.85 3.18 2.03–4.97 2.37–4.25 Nulliparous 1.73 1.26–2.38 4.82 2.77–8.40 2.20–10.55 Previous cesarean delivery 6.42 4.33–9.52 20.55 10.9–38.6 10.38–40.69 Malpresentation (nonvertex) 58.3 27.7–122.7 146.85 59.6–362 75.9–284 - Table 5.
Other Outcomes of Patients Exposed or Not Exposed to Active Management of Risk in Pregnancy at Term (AMOR-IPAT)
Outcome Exposed (n = 794) Nonexposed (n = 1,075) RiskRatio (95% CI) P Value CI = confidence interval; ROM = rupture of membranes; Hgb = hemoglobin; ICU = intensive care unit; NICU = neonatal intensive care unit. * Calculated using the Wilcoxon rank-sum test. † Numerator/denominator were 40/752 in the exposed group and 64/1,024 in the nonexposed group. ‡ Analyzed using Student’s t test. Maternal Thick meconium at ROM, % 1.2 3.8 0.45 (0.13–0.68) .001 Repetitive late decelerations, % 0.4 1.7 0.23 (0.07–0.76) .007 Major perineal trauma (3rd/4th degree), % 8.1 9.5 0.90 (0.74–1.10) .32 Assisted (vacuum/forceps) vaginal delivery, % 17.5 16.0 1.06 (0.93–1.22) .22 Estimated blood loss, mean, cc 290 323 – <.001* Estimated blood loss, >500 cc, % 7.8 11.1 0.78 (0.62–0.99) .03 Use of carboprost, % 1.9 2.1 0.93 (0.62–1.38) .74 Anemia (Hgb <9 mg/dL),† % 6.6 5.8 1.08 (0.88–1.34) .48 Postpartum maximum temperature >100.4°F, % 3.5 4.7 0.83 (0.61–1.12) .20 Transfer to ICU or tertiary care, % 0 0.1 0 1.00 Death, % 0 0 – – Infant Birth weight, mean, g 3,454 3,483 – .17* Birth weight >4,000 g 11.6 12.9 0.93 (0.78–1.10) .43 Birth weight >4,500 g 0.8 2.2 0.48 (0.24–0.99) .02 Birth weight <2,500 g 1.5 1.8 0.91 (0.58–1.42) .72 Birth weight <3,000 g 14.2 14.9 0.97 (0.83–1.13) .74 Birth head circumference, mean, cm 34.4 34.4 – .67‡ Birth head circumference ≥37 cm, % 5.3 6.2 0.85 (0.58–1.25) .41 Venous cord blood pH <7.2, % 2.9 3.3 1.16 (0.90–1.51) .29 Apgar at 1 min <4, % 2.3 2.5 0.94 (0.65–1.35) .76 Apgar at 5 min <7, % 0.76 1.0 0.83 (0.43–1.58) .63 Apgar at 5 min <4, % 0.25 0.28 0.90 (0.15–5.39) 1.00 Regular nursery, % 94.3 92.6 1.02 (0.99–1.04) .16 Possible sepsis, % 2.53 2.59 0.97 (0.52–1.81) 1.00 NICU admission, % 2.3 4.2 0.66 (0.45–0.99) .03 Stillbirth, % 0.1 0.0 2.36 (2.23–2.48) .42 Perinatal mortality, % 0.0 0.0 – – Time intervals Maternal admit to discharge, h 44.1 44.9 – .59 Maternal admit to delivery, hr 9.2 8.7 – .02 Maternal first stage, h 5.7 5.4 – .66 Maternal second stage, min 41 54 – <.001 Maternal delivery to discharge, h 35.5 36.6 – .16 Infant delivery to discharge, h 38.6 39.3 – .46
Additional Files
Supplemental Appendixes
Supplemental Appendix 1. Upper Limit of the Optimal Time of Delivery (UL-OTD) Calculation Sheet. Supplemental Appendix 2. X-Factors and Timing of Induction
Files in this Data Supplement:
- Supplemental data: Appendix 1 - PDF file, 2 pages, 61 KB
- Supplemental data: Appendix 2 - PDF file, 1 page, 72 KB
The Article in Brief
A Preventive Approach to Obstetric Care in a Rural Hospital: Association Between Higher Rates of Preventive Labor Induction and Lower Rates of Cesarean Delivery
James M. Nicholson, MD, MSCE, and colleagues
Background Cesarean deliveries, which tend to have more medical complications than vaginal births, are increasing in North America. Clinicians have developed a method for inducing labor in women who are near the upper limit of the safest and most advantageous time period for their delivery. This study compares cesarean section rates between practitioners who often use this process (called the Active Management of Risk in Pregnancy at Term, or AMOR-IPAT) and those who do not.
What This Study Found In this 4-year study at a rural hospital, patients of clinicians who practiced AMOR-IPAT had a significantly lower cesarean delivery rate than patients of other clinicians. Women who received AMOR-IPAT did not have higher rates of other birth complications.
Implications
- As rates of cesarean deliveries rise, the authors encourage clinicians to consider the potential benefits of AMOR-IPAT as an alternative method of maternity care.
- The authors call for more study of this possible approach to preventing cesarean deliveries.
