Outcomes in low-risk patients before and after an institutional policy offering 39-week elective induction of labor

Figures & data

Figure 1. Flow diagram depicting patients identified for inclusion in final analysis.

Legend: None

Table 1. Demographics of low-risk pregnant patients before and after adoption of institution-wide policy offering elective induction at ≥39 0/7 weeks.

Characteristic	Pre-eIOL (N = 2521)	During-eIOL (N = 5410)	Post-eIOL (N = 2827)	p-value^a
Type of labor				<0.001
Spontaneous	485 (19.2)	999 (18.5)	276 (9.8)
Induction	912 (36.2)	2214 (40.9)	1813 (64.1)
Augmented	1124 (44.6)	2197 (40.6)	738 (26.1)
Maternal age (years)	25.6 ± 5.7	26.5 ± 5.8	27.2 ± 5.9	<0.001
Advanced maternal age (≥35 years)	186 (7.4)	478 (8.8)	335 (11.9)	<0.001
Race				<0.001
Black	1292 (51.8)	2471 (46.3)	1194 (42.9)
White	668 (26.8)	1705 (31.9)	930 (33.4)
Other	533 (21.4)	1164 (21.8)	658 (23.7)
Hispanic ethnicity	449 (18.0)	1018 (19.0)	592 (21.2)	0.009
BMI (kg/m^b)	27.9 ± 6.9	27.8 ± 6.9	27.8 ± 6.8	0.83
Obesity (BMI ≥30)	710 (32.0)	1589 (30.1)	802 (29.6)	0.17
Nulliparous	1177 (46.7)	2475 (45.8)	1346 (47.6)	0.28
Married	948 (37.9)	2196 (40.8)	1259 (44.7)	<0.001
Private insurance	721 (28.7)	1881 (34.8)	1251 (44.6)	<0.001
GA at intake to care^b	14.8 ± 7.4	13.6 ± 7.2	13.4 ± 7.2	<0.001

Data presented as n (%) or mean ± SD as appropriate.

^a p-value expresses the differences among all three groups.

^b GA at intake to care = GA at first ultrasound or first prenatal care visit (whichever occurred earlier).

Table 2. Primary and secondary outcomes among low-risk pregnant patients before and after adoption of institution-wide policy offering elective induction at ≥39 0/7 weeks.

OUTCOME	Pre-eIOL (N = 2521)	During-eIOL (N = 5410)	Post-eIOL (N = 2827)	During vs Pre-eIOL OR (95% CI) aOR (95% CI)^a	Post vs Pre-eIOL OR (95% CI) aOR (95% CI)^a
Maternal outcomes
Cesarean delivery	441 (17.5)	795 (14.7)	433 (15.3)	0.81 (0.72–0.92) 0.79 (0.69–0.90)	0.85 (0.74–0.99) 0.83 (0.72–0.96)
Chorioamnionitis	92 (3.7)	382 (7.1)	163 (5.8)	2.01 (1.59–2.53) 1.99 (1.57–2.51)	1.62 (1.24–2.10) 1.61 (1.24–2.10)
Operative vaginal delivery	47 (1.9)	263 (4.9)	140 (5.0)	2.69 (1.97–3.68) 2.74 (2.00–3.75)	2.74 (1.96–3.83) 2.84 (2.03–3.98)
Postpartum hemorrhage	135 (5.4)	659 (12.2)	255 (9.0)	2.45 (2.02–2.97) 2.42 (2.00–2.93)	1.75 (1.41–2.18) 1.73 (1.39–2.15)
Neonatal outcomes
GA at delivery (weeks)	40.0 ± 0.7	40.0 ± 0.7	39.7 ± 0.6	<0.001
GA at delivery <40 weeks	1197 (47.5)	2798 (51.7)	1935 (68.5)	1.19 (1.08-–1.30) 1.16 (1.05–1.28)	2.40 (2.15–2.68) 2.35 (2.10–2.63)
GA at delivery ≥41 weeks	361 (14.3)	652 (12.1)	138 (4.9)	0.82 (0.71–0.94) 0.86 (0.75–0.99)	0.31 (0.25–0.38) 0.33 (0.27–0.40)
Stillbirth	3 (0.1)	4 (0.1)	2 (0.1)	0.62 (0.14–2.78) 0.61 (0.14–2.75)	0.60 (0.10–3.57) 0.59 (0.10–3.58)
5-min APGAR ≤3	30 (1.2)	60 (1.1)	41 (1.5)	0.93 (0.60–1.45) 0.97 (0.62–1.51)	1.22 (0.76–1.96) 1.28 (0.79–2.06)
Neonatal birthweight (g)	3390.1 ± 455.8	3387.8 ± 423.8	3328.5 ± 416.3	<0.001
Birthweight ≥4000 g	195 (8.3)	407 (7.8)	146 (5.4)	0.93 (0.78–1.11) 0.88 (0.73–1.05)	0.63 (0.51–0.79) 0.56 (0.45–0.70)
Small-for-GA	509 (20.3)	901 (16.7)	513 (18.2)	0.79 (0.70–0.89) 0.81 (0.71–0.91)	0.87 (0.76–1.00) 0.91 (0.80–1.05)
Large-for-GA	145 (5.8)	316 (5.9)	125 (4.4)	1.01 (0.83–1.24) 0.94 (0.76–1.15)	0.76 (0.59–0.97) 0.66 (0.52–0.85)
NICU admission	232 (9.2)	462 (8.5)	295 (10.4)	0.92 (0.78–1.09) 0.95 (0.81–1.13)	1.15 (0.96–1.38) 1.21 (1.00–1.45)
Hypoglycemia (<35 mg/dL)	32 (1.3)	65 (1.2)	16 (0.6)	0.95 (0.62–1.45) 0.94 (0.61–1.43)	0.44 (0.24–0.81) 0.44 (0.24–0.81)

Data presented as n (%) or mean ± SD as appropriate.

p-value presented for continuous variables. “-”indicates unable to calculate.

GA: gestational age. NICU : Neonatal intensive care unit.

There were no maternal deaths or neonatal deaths within 28 days of life.

^a Adjusted for maternal age, GA at intake, and marital status; Pre-eIOL is the referent.

Table 3. Primary and secondary outcomes among low-risk patients undergoing labor induction before and after adoption of institution-wide policy offering elective induction at ≥39 0/7 weeks.

OUTCOME	Pre-eIOL (N = 912)	During-eIOL (N = 2214)	Post-eIOL (N = 1813)	During vs Pre-eIOL aOR (95% CI)^a	Post vs Pre-eIOL aOR (95% CI)^a
Maternal outcomes
Cesarean delivery	253 (27.7)	463 (21.0)	331 (18.3)	0.68 (0.57–0.82)	0.58 (0.48–0.70)
Chorioamnionitis	45 (4.9)	208 (9.4)	110 (6.1)	1.99 (1.42–2.78)	1.24 (0.87–1.79)
Operative vaginal delivery	20 (2.2)	102 (4.6)	94 (5.2)	2.11 (1.30–3.43)	2.37 (1.45–3.88)
Postpartum hemorrhage	53 (5.8)	321 (14.5)	190 (10.5)	2.71 (2.01–3.67)	1.87 (1.36–2.57)
Neonatal outcomes
GA at delivery (weeks)	40.2 ± 0.8	40.0 ± 0.8	39.7 ± 0.6	<0.001
GA at delivery <40 weeks	360 (39.5)	1101 (49.7)	1286 (70.9)	1.49 (1.27–1.74)	3.63 (3.06–4.29)
GA at delivery ≥41 weeks	238 (26.1)	436 (19.7)	96 (5.3)	0.70 (0.58–0.85)	0.16 (0.12–0.21)
Stillbirth	2 (0.2)	4 (0.2)	1 (0.1)	0.81 (0.15–4.43)	0.25 (0.02–2.79)
5-min APGAR ≤3	12 (1.3)	30 (1.4)	23 (1.3)	1.04 (0.53–2.04)	1.01 (0.50–2.05)
Neonatal birthweight (g)	3428.0 ± 466.2	3399.6 ± 454.7	3337.5 ± 421.2	<0.001
Birthweight ≥4000 g	91 (10.8)	185 (8.7)	110 (6.4)	0.78 (0.60–1.02)	0.54 (0.40–0.73)
Small-for-GA	195 (21.5)	401 (18.1)	330 (18.2)	0.82 (0.67–0.99)	0.83 (0.68–1.02)
Large-for-GA	70 (7.7)	136 (6.2)	93 (5.1)	0.78 (0.57–1.05)	0.62 (0.45–0.86)
NICU admission	104 (11.4)	234 (10.6)	195 (10.8)	0.96 (0.75–1.24)	1.01 (0.78–1.31)
Hypoglycemia (<35 mg/dL)	13 (1.4)	38 (1.7)	11 (0.6)	1.21 (0.64–2.28)	0.43 (0.19–0.96)

Data presented as n (%) or mean ± SD as appropriate.

p-value presented for continuous variables. “-”indicates unable to calculate.

GA: gestational age; NICU: neonatal intensive care unit.

There were no maternal deaths or neonatal deaths within 28 days of life.

^a Adjusted for maternal age, GA at intake, and marital status; Pre-eIOL is the referent.

Data availability statement

Data available on request from the authors.