There were 43577 deliveries in Harvard University Partners Healthcare Systems (PARTNERS) from January 1, 2016 to December 31, 2018, including 29,943 vaginal deliveries and 13,634 cesarean deliveries, the rate of cesarean delivery was 31.3%. There were 7109 multiparous women who planned for vaginal delivery and encountered the labor process, 76.3% with epidural analgesia, 27.8% with oxytocin (Table 1). The duration of first stage was 6.2(3.6-10.0) hours in multiparous women, the second stage was 0.3(0.2-0.7) hours, the total stage was 6.9(4.1-10.7) hours. The rate of overall adverse outcomes was 23.6%, the rate of maternal adverse outcomes was 9.4%, the rate of neonatal adverse outcomes was 17.1%, other adverse outcomes were showed in Table 2.
Table 1 Demographics and obstetrics characteristics of multiparous women (n=7109).
|
Median/n
|
IQR/%
|
Duration of stage of labor
|
|
|
First stage (hour) *
|
6.2
|
3.6-10.0
|
<6h
|
3398
|
47.8
|
6-11.9h
|
2512
|
35.3
|
12-17.9h
|
820
|
11.5
|
18-23.9h
|
228
|
3.2
|
≥ 24h
|
151
|
2.1
|
Second stage (hour) *
|
0.3
|
0.2-0.7
|
< 1h
|
5791
|
81.5
|
1-1.9h
|
776
|
10.9
|
2-2.9h
|
278
|
3.9
|
3-3.9h
|
129
|
1.8
|
≥ 4h
|
135
|
1.9
|
Total stage (hour) *
|
6.9
|
4.1-10.7
|
< 12h
|
5717
|
80.4
|
12-23.9h
|
1208
|
17.0
|
≥ 24h
|
184
|
2.6
|
Gestational age(weeks) *
|
39.6
|
39.0-40.3
|
Maternal age(years) *
|
33.0
|
30.0-36.0
|
Maternal Height (cm) *
|
162.6
|
160.0-167.6
|
Gestational weight gain(kg) *
|
14.0
|
10.0-17.0
|
Maternal BMI(kg/m2) *
|
29.4
|
26.6-32.6
|
Gravidity*
|
3.0
|
2.0-4.0
|
Parity*
|
2.0
|
2.0-3.0
|
Baby weight (g) *
|
3459
|
3175-3750
|
Baby height (cm) *
|
50.8
|
48.3-52.1
|
Ethnicity
|
|
|
Non-Hispanic White
|
4671
|
65.7
|
Non-Hispanic Black
|
558
|
7.9
|
Hispanic
|
273
|
3.8
|
Asian or Pacific Islanders
|
737
|
10.4
|
Other or Unknown
|
870
|
12.2
|
Epidural analgesia
|
5423
|
76.3
|
Induction
|
1647
|
23.2
|
Oxytocin
|
1975
|
27.8
|
Data was presented as n (%) or *median (interquartile range, non-normal distribution).
Table 2 Adverse delivery outcomes in multiparous women.
|
n
|
%
|
Overall outcomes
|
1677
|
23.6
|
Maternal outcomes
|
671
|
9.4
|
Referral cesarean delivery
|
98
|
1.4
|
Instrumental delivery
|
207
|
2.9
|
Postpartum hemorrhage
|
155
|
2.2
|
III and IV degree laceration
|
78
|
1.1
|
Length of stay ≥90th
|
332
|
4.7
|
Neonatal outcomes
|
1213
|
17.1
|
NICU
|
411
|
5.8
|
Shoulder dystocia
|
185
|
2.6
|
Apgar ≤7(5 min)
|
89
|
1.3
|
Neonatal resuscitation
|
790
|
11.1
|
Assisted ventilation
|
181
|
2.5
|
Overall outcomes include maternal and neonatal adverse outcomes.
With the prolongation of first stage, the rates of overall adverse outcomes were 21%, 23.4%, 28.8%, 35.5%, 38.4% in subgroups <6h, 6-11.9h, 12-17.9h, 18-23.9h, ≥24h, the rates increased significantly (X2=57.64, P<0.001). The rate of maternal adverse outcomes was 7.2%, 8.8%, 13.8%, 20.2%, 29.8% respectively, which increased significantly (X2=121.38, P<0.001); The rate of neonatal adverse outcomes was 16.0%, 17.3%, 19.3%, 21.5%, 18.5% respectively, which increased significantly (X2=7.75, P=0.005). There were significant differences in the incidence of referral cesarean delivery, instrumental delivery, length of stay ≥90th, shoulder dystocia, Apgar ≤7(5 min), neonatal resuscitation, assisted ventilation in different duration of the first stage (Table 3, Figure 2). In order to assess the effect of duration of labor on adverse outcomes, we made the following analysis, with <6h as the reference. Multivariable logistic regression showed that ARR(95%CI) of overall adverse outcomes were 1.10(0.92,1.31), 1.33(1.04,1.70), 1.80(1.21,2.68), 2.57(1.60,4.15) in subgroups of 6-11.9h, 12-17.9h, 18-23.9h, ≥24h; ARR(95% CI) of maternal adverse outcomes were 1.31(1.01,1.71), 2.42(1.74,3.37), 3.15(1.92,5.18), 5.52(3.19,9.58); ARR(95% CI) of neonatal adverse outcomes were 1.04(0.85,1.26), 0.95(0.71,1.27), 1.28(0.81,2.02), 1.27(0.71,2.25). The risk of referral cesarean delivery and length of stay ≥90th increased with prolonged first stage. This was showed in Additional file 1: Table S1, Figure 3. In order to understand the impact of different cutoff values on the risk of overall adverse outcomes, the first stage <6h and ≥6h were compared, ARR(95% CI) was 1.23(1.05, 1.43); if the cutoff values were 12h, 18h, 24h, ARR(95% CI) were 1.48(1.22, 1.80), 1.92(1.41, 2.59), 2.33(1.45, 3.72); ARR(95% CI) of maternal adverse outcomes were 1.76(1.40, 2.22), 2.55(1.98, 3.28), 3.61(2.13, 4.40), 4.05(2.39, 6.86), ARR(95% CI) of neonatal adverse outcomes were 1.04(0.87,1.24), 1.03(0.82,1.30), 1.26(0.88,1.81), 1.25(0.71,2.19) with 6h,12h, 18h, 24h as cutoff values. The risk of referral cesarean delivery and length of stay ≥90th increased with the change of cutoff values. Other outcomes were showed in Additional file 2: Table S2, Figure 3.
Table 3 Adverse outcomes in the first stage of labor in multiparous women (n=7109).
|
Duration of First stage of labor
|
Linear trend X2
|
P
|
<6h
|
6-11.9h
|
12-17.9h
|
18-23.9h
|
≥24h
|
Overall outcomes
|
714(21.0)
|
588(23.4)
|
236(28.8)
|
81(35.5)
|
58(38.4)
|
57.64
|
<0.001
|
Maternal outcomes
|
246(7.2)
|
221(8.8)
|
113(13.8)
|
46(20.2)
|
45(29.8)
|
121.38
|
<0.001
|
Referral cesarean delivery
|
28(0.8)
|
29(1.2)
|
20(2.4)
|
13(5.7)
|
8(5.3)
|
50.97
|
<0.001
|
Instrumental delivery
|
77(2.3)
|
72(2.9)
|
35(4.3)
|
12(5.3)
|
11(7.3)
|
23.46
|
<0.001
|
Postpartum hemorrhage
|
72(2.5)
|
53(2.5)
|
18(2.6)
|
9(4.7)
|
3(2.3)
|
0.73
|
0.393
|
III and IV degree laceration
|
34(1.1)
|
23(1.0)
|
14(1.9)
|
4(2.0)
|
3(2.3)
|
3.76
|
0.053
|
Length of stay ≥90th
|
100(2.9)
|
100(4.0)
|
67 (8.2)
|
31(13.6)
|
34(22.5)
|
160.81
|
<0.001
|
Neonatal outcomes
|
543(16.0)
|
435(17.3)
|
158(19.3)
|
49(21.5)
|
28(18.5)
|
7.75
|
0.005
|
NICU
|
184(5.4)
|
150(6.0)
|
54(6.6)
|
16(7.0)
|
7(4.6)
|
1.14
|
0.285
|
Shoulder dystocia
|
76(2.3)
|
73(3.0)
|
20(2.5)
|
10(4.5)
|
6(4.1)
|
4.33
|
0.037
|
Apgar ≤7(5 min)
|
24(0.7)
|
42(1.7)
|
15(1.8)
|
5(2.2)
|
3(2.0)
|
12.66
|
<0.001
|
Neonatal resuscitation
|
354(11.0)
|
287(12.2)
|
101(13.3)
|
31(15.3)
|
17(13.1)
|
5.77
|
0.016
|
Assisted ventilation
|
72(2.2)
|
66(2.8)
|
31(4.1)
|
8(3.9)
|
4(2.7)
|
7.13
|
0.008
|
Data was presented as n(%). Linear trend Chi-square test for categorical data.
With the prolongation of second stage of labor, the rates of overall adverse outcomes were 20.0%, 30.7%, 38.5%, 61.2%, 69.6% in subgroups <1h, 1-1.9h, 2-2.9h, 3-3.9h, ≥4h (X2=349.70, P<0.001). The rate of maternal adverse outcomes increased from 5.9%, 14.6%, 25.2%, 45.0%, to 64.4% (X2=821.97, P<0.001); The rate of neonatal adverse outcomes was 16.0%, 19.6%, 21.2%, 31.8%, 27.4%, which increased significantly (X2=38.06, P<0.001). There were significant differences in the rate of referral cesarean delivery, instrumental delivery, postpartum hemorrhage, III and IV degree laceration, length of stay ≥90th, NICU, Apgar ≤7(5 min), neonatal resuscitation, assisted ventilation in second stage of labor (Table 4 , Figure 4). With <1h as the reference group of second stage, ARR (95% CI) of 1-1.9h, 2-2.9h, 3-3.9h, 4h were 1.89(1.50, 2.39), 2.22 (1.55, 3.18), 10.64 (6.09, 18.59), 11.75(6.55, 21.08) in overall adverse outcomes; ARR(95%CI) were 2.51(1.83,3.44), 4.69(3.09,7.12), 13.87(8.21,23.44), 28.63(16.26,50.40) in maternal outcomes; ARR(95%CI) were 1.46(1.12,1.91), 1.28(0.83,1.98), 3.89(2.33,6.49), 1.68(0.91,3.10) in neonatal outcomes; other outcomes showed in Additional file 3: Table S3, Figure 5. Regarding the impact of cutoff values of second stage on the risk of adverse outcomes, ARR (95% CI) of overall adverse outcomes were 2.71(2.25, 3.26), 4.08(3.15, 5.28), 9.51(6.33, 14.28), 9.31(5.20, 16.65) with 1h, 2h, 3h, 4h as the cutoff values; ARR (95% CI) of maternal adverse outcomes were 4.63(3.64,5.87), 7.80(5.85,10.41), 14.11(9.59,20.78), 18.24(10.47,31.78); ARR (95% CI) of neonatal adverse outcomes were 1.61(1.30,2.00), 1.75(1.30,2.35), 2.48(1.68,3.66), 1.48(0.81,2.73). Other adverse outcomes were showed in Additional file 4: Table S4, Figure 5.
Table 4 Adverse outcomes in the second stage of labor in multiparous women (n=7109).
|
Duration of second stage of labor
|
Linear trend X2
|
P
|
<1h
|
1-1.9h
|
2-2.9h
|
3-3.9h
|
≥4h
|
Overall outcomes
|
1159(20.0)
|
238(30.7)
|
107(38.5)
|
79(61.2)
|
94(69.6)
|
349.70
|
<0.001
|
Maternal outcomes
|
343(5.9)
|
113(14.6)
|
70(25.2)
|
58(45.0)
|
87(64.4)
|
821.97
|
<0.001
|
Referral cesarean delivery
|
6(0.1)
|
13(1.7)
|
17(6.1)
|
18(14.0)
|
44(32.6)
|
989.84
|
<0.001
|
Instrumental delivery
|
88(1.5)
|
37(4.8)
|
28(10.1)
|
25(19.4)
|
29(21.5)
|
375.02
|
<0.001
|
Postpartum hemorrhage
|
90(1.8)
|
25(3.8)
|
6(2.7)
|
12(10.4)
|
22(19.0)
|
130.31
|
<0.001
|
III and IV degree laceration
|
48(0.9)
|
11(1.6)
|
6(2.5)
|
6(5.8)
|
7(7.1)
|
46.88
|
<0.001
|
Length of stay≥90th
|
150(2.6)
|
54(7.0)
|
38(13.7)
|
34(26.4)
|
56(41.5)
|
614.33
|
<0.001
|
Neonatal outcomes
|
924(16.0)
|
152(19.6)
|
59(21.2)
|
41(31.8)
|
37(27.4)
|
38.06
|
<0.001
|
NICU
|
295(5.1)
|
55(7.1)
|
28(10.1)
|
18(14.0)
|
15(11.1)
|
36.42
|
<0.001
|
Shoulder dystocia
|
150(2.6)
|
22(2.9)
|
7(2.6)
|
4(3.3)
|
2(1.5)
|
0.05
|
0.83
|
Apgar ≤7(5 min)
|
48(0.8)
|
17(2.2)
|
6(2.2)
|
13(10.1)
|
5(3.7)
|
64.22
|
<0.001
|
Neonatal resuscitation
|
609(11.2)
|
95(13.1)
|
30(11.9)
|
30(25.2)
|
26(21.1)
|
24.22
|
<0.001
|
Assisted ventilation
|
123(2.3)
|
23(3.2)
|
10(4.0)
|
14(11.8)
|
11(8.9)
|
48.11
|
<0.001
|
Data was presented as n(%). Linear trend Chi-square test for categorical data.
The total stage of labor was stratified to <12h, 12-23.9h, and ≥24h. With the increase of total stage of labor, the rate of overall adverse outcomes were 21.5%, 30.8%, 42.4% (X2=84.90, P<0.001); the rate of material adverse outcomes were 7.3%, 15.7%, 33.2% (X2=195.48, P<0.001); the rate of neonatal adverse outcomes were 16.4%, 20.0%, 19.6% (X2=8.61, P=0.003). The rate was (significantly) different in terms of referral cesarean delivery, instrumental delivery, postpartum hemorrhage, III and IV degree laceration, length of stay ≥90th, Apgar ≤7(5 min), neonatal resuscitation, and assisted ventilation (Table 5, Figure 6). With total stage of labor <12h as the reference, the risk of overall adverse outcomes, ARR (95% CI) were 1.41(1.16,1.72), 3.17 (2.10,4.80) in subgroups of 12-23.9h, ≥24h, the risk of maternal outcomes, ARR (95% CI) was 2.40 (1.84,3.12), 6.57 (4.14,10.42), and the risk of neonatal outcomes, ARR (95% CI) was 1.01 (0.80,1.28), 1.41 (0.86,2.30), (Additional file 5: Table S5, Figure 7). Regarding the impact of the total stage on the risk of overall adverse outcomes, ARR (95% CI) were 1.59(1.32,1.91) with 12h, 24h as the cutoff values; ARR (95% CI) of maternal adverse outcome was 2.84(2.23,3.62) with 12h as the cutoff value, but there was no effect on the neonatal adverse outcomes (Additional file 6: Table S6, Figure 7).
Table 5 Adverse outcomes in the total stage of labor in multiparous women. (n=7109).
|
Duration of total stage of labor
|
Linear trend X2
|
P
|
<12h
|
12-23.9h
|
≥24h
|
Overall outcomes
|
1227(21.5)
|
372(30.8)
|
78(42.4)
|
84.90
|
<0.001
|
Maternal outcomes
|
420(7.3)
|
190(15.7)
|
61(33.2)
|
195.48
|
<0.001
|
Referral cesarean delivery
|
43(0.8)
|
39(3.2)
|
16(8.7)
|
111.98
|
<0.001
|
Instrumental delivery
|
129(2.3)
|
62(5.1)
|
16(8.7)
|
51.34
|
<0.001
|
Postpartum hemorrhage
|
113(2.3)
|
34(3.3)
|
8(5.1)
|
6.86
|
0.009
|
III and IV degree laceration
|
55(1.1)
|
18(1.7)
|
5(3.1)
|
6.96
|
0.008
|
Length of stay≥90th
|
172(3.0)
|
116(9.6)
|
44(23.9)
|
239.48
|
<0.001
|
Neonatal outcomes
|
936(16.4)
|
241(20.0)
|
36(19.6)
|
8.61
|
0.003
|
NICU
|
313(5.5)
|
89(7.4)
|
9(4.9)
|
2.91
|
0.088
|
Shoulder dystocia
|
143(2.5)
|
35(3.0)
|
7(3.9)
|
1.68
|
0.194
|
Apgar ≤7(5 min)
|
58(1.0)
|
27(2.2)
|
4(2.2)
|
11.83
|
0.001
|
Neonatal resuscitation
|
615(11.4)
|
154(13.9)
|
21(13.1)
|
4.62
|
0.032
|
Assisted ventilation
|
131(2.4)
|
44(4.0)
|
6(3.8)
|
7.70
|
0.006
|
Data was presented as n(%). Linear trend Chi-square test for categorical data.