Table 1. Baseline Maternal Characteristics in the Four Groups Categorized by Interpregnancy Interval.
Maternal Parameters
|
IPI of IPI of IPI of IPI of
|
P value
|
< 24 mon
(n = 121)
|
24-59 mon
(n = 583)
|
60-119 mon
(n = 712)
|
≥120 mon
(n = 246)
|
Maternal age at index conception (y)
|
30.75±3.5
|
31.43±3.31
|
33.88±3.2
|
37.14±2.95
|
< 0.001
|
≥ 35
|
16 (13.2)
|
86 (14.8)
|
284 (39.9)
|
195 (79.3)
|
0.001
|
< 35
|
105 (86.8)
|
497 (85.2)
|
428 (60.1)
|
51 (20.7)
|
|
Education (y)
|
|
|
|
|
< 0.001
|
≤ 12
|
9 (7.4)
|
36 (6.2)
|
52 (7.4)
|
23 (9.4)
|
|
13-16
|
10 (8.3)
|
48 (8.3)
|
74 (10.5)
|
34 (13.9)
|
|
≥ 17
|
102 (84.3)
|
497 (85.5)
|
578 (82.1)
|
188 (76.7)
|
|
BMI, No. (Kg/m2)
|
|
|
|
|
0.005
|
< 18
|
19 (15.7)
|
74 (12.7)
|
55 (7.7)
|
14 (5.7)
|
|
18-23.9
|
80 (66.1)
|
395 (67.8)
|
525 (73.7)
|
173 (70.3)
|
|
24-27.9
|
22 (14.9)
|
93 (16)
|
116 (16.3)
|
51 (20.7)
|
|
> 28
|
4 (3.3)
|
21 (3.6)
|
16 (2.2)
|
8 (3.3)
|
|
Number of previous pregnancies
|
|
|
|
|
< 0.001
|
≥ 3
|
66 (54.5)
|
366 (62.8)
|
530 (74.4)
|
218 (88.6)
|
|
< 3
|
55 (45.5)
|
217 (37.2)
|
182 (25.6)
|
28 (11.4)
|
|
Parity ≥ 2
|
16 (13.2)
|
38 (6.5)
|
26 (3.7)
|
10 (4.1)
|
< 0.001
|
Prior cesareans ≥ 2
|
16 (13.2)
|
33 (5.7)
|
21 (2.9)
|
5 (2.0)
|
0.001
|
Prior vaginal birth
|
4 (3.3)
|
8 (1.4)
|
11 (1.5)
|
6 (2.4)
|
0.384
|
IVF-ET
|
2 (3.5)
|
6 (1.0)
|
4 (0.6)
|
3 (1.2)
|
0.007
|
Preexisting hypertension
|
2 (1.7)
|
2 (0.3)
|
4 (0.6)
|
4 (1.6)
|
0.128
|
Preexisting diabetes
|
0 (0)
|
3 (0.5)
|
2 (0.3)
|
2 (0.8)
|
0.60
|
Gestational age at delivery (weeks)
|
38.05±1.75
|
38.07± 1.81
|
38.12± 1.76
|
37.72± 2.21
|
0.027
|
Mode of delivery
|
|
|
|
|
0.178
|
Repeated cesarean section
|
117 (96.7)
|
560 (96.1)
|
696 (97.8)
|
242 (98.4)
|
|
Vaginal birth after CS
|
4 (3.3)
|
23 (3.9)
|
16 (2.2)
|
4 (1.6)
|
|
Type of repeated cesarean section
|
|
|
|
|
|
Emergency cesarean section
|
38 (32.2)
|
179 (31.9)
|
220 (31.6)
|
87 (36.0)
|
0.641
|
CS with indications
|
45 (37.2)
|
191 (34)
|
216 (31)
|
85 (35.1)
|
0.403
|
Data are expressed as mean ± SD, or n (%) with p-value from exact chi-square.
IPI, interpregnancy interval.
BMI, body mass index; IVF-ET, in vitro fertilization and embryo transfer.
Table 2. Rates of Maternal and Neonatal outcomes in the Four Groups Categorized by Interpregnancy Interval.
Perinatal outcome
|
IPI of IPI of IPI of IPI of
|
P value
|
< 24 mon
(n = 121)
|
24-59 mon
(n = 583)
|
60-119 mon
(n = 712)
|
≥ 120 mon
(n = 246)
|
Anemia
|
22 (18.2)
|
57 (9.8)
|
90 (12.6)
|
32 (13)
|
0.057
|
GHP
|
15 (4.2)
|
5 (2.6)
|
22 (3.1)
|
15 (6.1)
|
0.036
|
GDM
|
21 (18.2)
|
120 (20.6)
|
156 (21.9)
|
86 (34.9)
|
0.001
|
Grade A1
|
17 (14.9)
|
107 (18.4)
|
136 (19.1)
|
79 (32.1)
|
|
Grade A2
|
4 (3.3)
|
13 (2.2)
|
20 (2.8)
|
7 (2.8)
|
|
Placenta inherence
|
5 (8.9)
|
46 (7.9)
|
50 (7.0)
|
21 (8.5)
|
0.9
|
Placental position
|
|
|
|
|
0.256
|
Normal
|
107 (88.4)
|
522 (89.5)
|
637 (89.5)
|
215 (87.4)
|
|
Low placenta
|
9 (7.4)
|
18 (3.1)
|
31 (4.4)
|
16 (6.5)
|
|
Partial or marginal placenta previa
|
1 (0.8)
|
10 (1.7)
|
16 (2.2)
|
4 (1.6)
|
|
Complete placenta previa
|
4 (3.3)
|
33 (5.7)
|
28 (3.9)
|
11 (4.5)
|
|
Pernicious placenta
|
7 (5.8)
|
40 (6.9)
|
40 (5.6)
|
19 (7.7)
|
0.629
|
Placenta accreta
|
11 (9.1)
|
46 (7.9)
|
50 (7.0)
|
21 (8.5)
|
0.787
|
PROM
|
17 (14)
|
68 (11.7)
|
108 (15.2)
|
29 (11.8)
|
0.258
|
Uterine rupture
|
12 (9.9)
|
63 (10.8)
|
58 (8.1)
|
12 (4.9)
|
0.041
|
Placental abruption
|
2 (1.7)
|
3 (0.5)
|
2 (0.3)
|
4 (1.6)
|
0.258
|
Postpartum hemorrhage
|
5 (4.1)
|
35 (6.0)
|
43 (6.0)
|
16 (6.5)
|
0.835
|
Hysterectomy
|
2 (1.7)
|
6 (1.0)
|
7 (1.0)
|
3 (1.2)
|
0.921
|
Preterm birth
|
16 (13.2)
|
72 (12.3)
|
77 (10.8)
|
39 (15.9)
|
0.282
|
Preterm birth < 34 weeks
|
5 (4.1)
|
15 (2.6)
|
11 (1.5)
|
15 (6.1)
|
0.002
|
Birth weight (g)
|
3247±499
|
3233±522
|
3290±502
|
3174±558
|
0.017
|
Birth length (cm)
|
49.25±2.39
|
48.99±2.89
|
49.23±2.52
|
48.68±2.89
|
0.035
|
LBW
|
3 (5.5)
|
38 (6.5)
|
40 (5.6)
|
26 (10.6)
|
0.071
|
1-min Apgar score <10
|
5 (4.1)
|
3 (5.3)
|
28 (3.9)
|
13 (5.3)
|
0.625
|
NICU admission
|
17 (12.7)
|
57 (9.8)
|
72 (10.1)
|
28 (11.4)
|
0.519
|
Data are expressed as mean ± SD, or n (%) with p-value from exact chi-square.
IPI, interpregnancy interval.
GDM, gestational diabetes mellitus; GHP, gestational hypertension; PROM, premature rupture of membrane.
LBW, the birth weight of newborns is less than 2500g; NICU, neonatal intensive care.
Table 3. Association among Anemia, GHP, GDM and IPI in the Three Groups with IPI of <24, 60-119 and ≥ 120 months.
|
IPI of <24 mon (n = 121)
|
IPI of 60-119 mon (n = 712)
|
IPI of ≥ 120 mon (n = 246)
|
aOR (95% CI)
|
P value
|
aOR (95% CI)
|
P value
|
aOR (95% CI)
|
P value
|
Anemia
|
2.09 (1.21-3.62)
|
0.008
|
1.37 (0.94-1.98)
|
0.098
|
1.39 (0.81-2.38)
|
0.232
|
GHP
|
1.91 (0.67-5.45)
|
0.227
|
1.06 (0.53-2.13)
|
0.874
|
1.65 (0.69-3.98)
|
0.262
|
GDM
|
1.28 (0.73-2.23)
|
0.395
|
1.21 (0.89-1.64)
|
0.218
|
0.86 (0.58-1.3)
|
0.482
|
IPI, interpregnancy interval.
aOR, adjusted odds ratio; CI, confidential index; GHP, gestational hypertension; GDM, gestational diabetes mellitus.
Adjusted for maternal age, maternal body mass index, education status, gravidity, number of previous cesarean section.
Table 4. Association between other Perinatal Outcomes and IPI in the Three Groups with IPI of <24, 60-119 and ≥ 120 months.
|
Index
|
IPI of <24 mon
(n = 121)
|
IPI of 60-119 mon
(n = 712)
|
IPI of ≥ 120 mon
(n = 246)
|
P value
|
aOR (95% CI)
|
aOR (95% CI)
|
aOR (95% CI)
|
Abnormal placental position
|
0.084
|
0.92 (0.77-1.1)
|
1.09 (0.91-1.3)
|
1.18 (0.82-1.97)
|
0.366
|
Pernicious placenta with or without placenta accreta
|
0.015
|
0.98 (0.79-1.22)
|
1.02 (0.82-1.26)
|
1.03 (0.67-1.98)
|
0.889
|
PROM
|
0.032
|
0.97 (0.82-1.14)
|
1.03 (0.87-1.22)
|
1.07 (0.76-1.63)
|
0.074
|
Uterine rupture
|
-0.265
|
1.30 (1.05-1,61)
|
0.77 (0.62-0.95)
|
0.59 (0.38-1.08)
|
0.014
|
Postpartum hemorrhage
|
0.060
|
0.94 (0.72-1.23)
|
1.06 (0.81-1.39)
|
1.13 (0.66-2.58)
|
0.662
|
Hysterectomy
|
0.054
|
0.95 (0.74-1.21)
|
1.06 (0.83-1.35)
|
1.11 (0.68-2.36)
|
0.666
|
1-min Apgar score <10
|
-0.252
|
1.28 (0.62-2.73)
|
0.78 (0.37-1.61)
|
0.61 (0.13-2.9)
|
0.504
|
NICU admission
|
-0.004
|
1.00 (0.82-1.23)
|
1.00 (0.81-1.22)
|
0.99 (0.66-1.91)
|
0.966
|
IPI, interpregnancy interval.
aOR, adjusted odds ratio; CI, confidential index; PROM, premature rupture of membrane.
Abnormal placental position, including low placenta, partial and complete placenta previa.
Table 5. Association between other Perinatal Outcomes and IPI in the Three Groups with IPI of <24, 60-119 and ≥ 120 months.
|
Index
|
IPI of <24 mon
(n = 121)
|
IPI of 60-119 mon
(n = 712)
|
IPI of ≥ 120 mon
(n = 246)
|
P value
|
aOR (95% CI)
|
aOR (95% CI)
|
aOR (95% CI)
|
Abnormal placental position
|
0.139
|
0.87 (0.71-1.06)
|
1.15 (0.94--1.4)
|
1.32 (0.89-1.97)
|
0.169
|
Pernicious placenta with or without placenta accreta
|
0.103
|
0.90 (0.71-1.14)
|
1.11 (0.88-1.41)
|
1.23 (0.77-1.98)
|
0.395
|
PROM
|
0.059
|
0.94 (0.78-1.13)
|
1.06 (0.88-1.28)
|
1.13 (0.78-1.63)
|
0.527
|
Uterine rupture
|
-0.193
|
1.21 (0.96-1.53)
|
0.82 (0.65-1.04)
|
0.68 (0.43-1.08)
|
0.102
|
Postpartum hemorrhage
|
0.162
|
0.85 (0.62-1.15)
|
1.18 (0.87-1.53)
|
1.38 (0.75-2.58)
|
0.303
|
Hysterectomy
|
0.145
|
0.87 (0.65-1.14)
|
1.16 (0.87-1.53)
|
1.34 (0.77-2.36)
|
0.312
|
1-min Apgar score <10
|
-0.272
|
1.31 (0.59-3.08)
|
0.76 (0.32-1.7)
|
0.58 (0.11-2.9)
|
0.516
|
NICU admission
|
0.102
|
0.90 (0.72-1.13)
|
1.11 (0.89-1.38)
|
1.23 (0.79-1.91)
|
0.365
|
IPI, interpregnancy interval.
aOR, adjusted odds ratio; CI, confidential index; PROM, premature rupture of membrane.
Abnormal placental position, including low placenta, partial and complete placenta previa.
Aadjusted for maternal age, maternal body mass index, education status, assisted reproductive technology, number of previous cesarean section, previous vaginal delivery, previous emergency cesarean section.
Table 6. Association between IPI and other Perinatal Outcomes in Women with Emergency Cesarean Section.
|
Index
|
IPI of <24 mon
(n = 121)
|
IPI of 60-119 mon
(n = 712)
|
IPI of ≥ 120 mon
(n = 246)
|
P value
|
aOR (95% CI)
|
aOR (95% CI)
|
aOR (95% CI)
|
Abnormal placental position
|
0.119
|
0.89 (0.63-1.24)
|
1.13 (0.81-1.57)
|
1.27 (0.66-2.48)
|
0.482
|
Pernicious placenta with or without placenta accreta
|
-0.036
|
1.04(0.73-1.47)
|
0.96 (0.68-1.37)
|
0.93 (0.46-1.88)
|
0.840
|
PROM
|
0.028
|
0.97 (0.74-1.28)
|
1.03 (0.78-1.35)
|
1.06 (0.61-1.83)
|
0.843
|
Uterine rupture
|
-0.249
|
1.28 (0.94-1.75)
|
0.78 (0.57-1.06)
|
0.61 (0.33-1.12)
|
0.113
|
Postpartum hemorrhage
|
0.215
|
0.81 (0.47-1.37)
|
1.24 (0.73-2.14)
|
1.54 (0.53-4.57)
|
0.430
|
Hysterectomy
|
0.265
|
0.77 (0.46-1.25)
|
1.30 (0.8-2.16)
|
1.70 (0.64-4.66)
|
0.293
|
1-min Apgar score <10
|
-0.503
|
1.65 (0.5-6.42)
|
0.61 (0.16-2.01)
|
0.37 (0.02-4.05)
|
0.428
|
NICU admission
|
0.035
|
0.97 (0.69-1.35)
|
1.04 (0.74-1.46)
|
1.07 (0.55-2.12)
|
0.838
|
IPI, interpregnancy interval.
aOR, adjusted odds ratio; CI, confidential index; PROM, premature rupture of membrane.
Abnormal placental position, including low placenta, partial and complete placenta previa.
Table 7. Association between IPI and other Perinatal Outcomes in Women with Emergency Cesarean Section.
|
Index
|
IPI of <24 mon
(n = 121)
|
IPI of 60-119 mon
(n = 712)
|
IPI of ≥ 120 mon
(n = 246)
|
P value
|
aOR (95% CI)
|
aOR (95% CI)
|
aOR (95% CI)
|
Abnormal placental position
|
0.160
|
0.85 (0.59-1.22)
|
1.17 (0.82-1.69)
|
1.38 (0.68-2.86)
|
0.382
|
Pernicious placenta with or without placenta accreta
|
0.057
|
0.95 (0.64-1.38)
|
1.06 (0.72-1.56)
|
1.12 (0.52-2.43)
|
0.772
|
PROM
|
0.068
|
0.93 (0.69-1.25)
|
1.07 (0.8-1.44)
|
1.15 (0.64-2.08)
|
0.653
|
Uterine rupture
|
-0.157
|
1.17 (0.84-1.63)
|
0.86 (0.61-1.19)
|
0.73 (0.38-1.42)
|
0.354
|
Postpartum hemorrhage
|
0.195
|
0.82 (0.44-1.49)
|
1.21 (0.67-2.27)
|
1.48 (0.45-5.14)
|
0.528
|
Hysterectomy
|
0.192
|
0.83 (0.47-1.42)
|
1.21 (0.71-2.14)
|
1.47 (0.5-4.56)
|
0.494
|
1-min Apgar score <10
|
-0.572
|
1.77 (0.47-8.86)
|
0.56 (0.12-2.14)
|
0.32 (0.01-4.58)
|
0.426
|
NICU admission
|
0.321
|
0.73 (0.49-1.06)
|
1.38 (0.94-2.04)
|
1.90 (0.89-4.17)
|
0.102
|
IPI, interpregnancy interval.
aOR, adjusted odds ratio; CI, confidential index; PROM, premature rupture of membrane.
Abnormal placental position, including low placenta, partial and complete placenta previa.
Adjusted for maternal age, maternal body mass index, education status, assisted reproductive technology, number of previous cesarean section, previous vaginal delivery.