The Association between Early Artificial Amniotomy and Chorioamnionitis in Nulliparous Induction of Labor
Table 1
Association between demographic variables and amniotomy exposure.
Variable
Early amniotomy
Late amniotomy
value*
= 398
= 1,169
Maternal age, yr
23 (19–29)
22 (19–28)
0.48
African American race, (%)
98 (26.3)
310 (28.3)
0.48
Chronic hypertension or preeclampsia, (%)
127 (31.9)
336 (28.7)
0.23
Pregestational or gestational diabetes, (%)
27 (6.8)
56 (4.8)
0.12
Obesity, (%)
23 (8.3)
104 (8.9)
0.72
HIV, (%)
0
0
Lupus, (%)
2 (0.5)
0
0.06
Smoking, (%)
8 (2)
22 (1.9)
0.83
Location of prenatal care, (%)
Private practice
251 (63.9)
744 (65.2)
0.71
Medicaid practice
134 (34.1)
368 (32.3)
No prenatal care
8 (2.0)
29 (2.5)
Gestational age at delivery, wk
39.6 (39.0–41.0)
40.0 (39.1–41.0)
0.07
Neonatal weight, gms
3275 (2895–3610)
3220 (2856–3556)
0.10
Indication for induction, (%)
Maternal
27 (51.9)
227 (52.7)
0.68
Fetal
25 (48.1)
198 (48.9)
Both
0
6 (1.4)
Method of Induction, (%)
Pitocin
329 (82.7)
962 (82.3)
0.87
Prostaglandin
224 (56.6)
576 (49.4)
0.01
Foley bulb
79 (20.0)
216 (18.5)
0.53
Multiple methods
227 (57.3)
606 (52.0)
0.06
Any cervical ripening
266 (67.2)
710 (60.9)
0.03
Epidural anesthesia, (%)
366 (94.1)
1,084 (94.1)
0.99
Maternal GBS positive, (%)
135 (36.1)
377 (34.2)
0.50
Number of vaginal exams, (%)
8 (6–11)
8 (6–10)
0.47
Meconium stained amniotic fluid, (%)
64 (16.4)
217 (18.7)
0.30
Fetal scalp electrode, (%)
181 (45.5)
395 (33.8)
<0.001
Intrauterine pressure catheter, (%)
232 (58.3)
533 (45.7)
<0.001
Year of delivery, (%)
2008
133 (33.6)
230 (19.7)
<0.001
2009
98 (24.8)
267 (22.9)
2010
55 (13.9)
334 (28.6)
2011
110 (27.8)
337 (28.9)
Cervical dilation at amniotomy (cm)
3 (3.0–3.5)
4.5 (4.0–5.2)
<0.001
Categorical data analyzed with chi-square tests and data reported as (%). Continuous data analyzed with nonparametric comparison of medians and reported as median (interquartile range).
