Open Document File - Utah Government Publications Online

2007 UTAH’S HEALTH: AN ANNUAL REVIEW
Table 3: Mode of Delivery by Parity
Nulliparous
Induced Labor* Non-Induced Labor
No. % No. % P Value
Primary cesarean section 196 10.9 391 10.5 NS
Instrumental vaginal delivery 366 22.8 590 17.7 < .001
Multiparous
Primary cesarean section 50 1.2 122 2.4 < .001
Instrumental vaginal delivery
NS = not statistically significant
* Induced labor in the absence of an identified
227 5.6 240 4.8 NS
Since instrumental delivery among nulliparous women was correlated with birth weight and maternal age, as well
as induction, we used a logistic regression model to adjust for these potentially confounding characteristics.
Instrumental delivery was designated as the dependent variable in the logistic model, with group (induction vs.
non-induction) as an independent variable, and birth weight and maternal age as covariates. The odds ratio for
instrumental delivery adjusted for these confounding factors is shown in Table 4. The nulliparous women in the
induced group were 1.36 times more likely to experience instrumental delivery compared to the nulliparous
women in the non-induced group, regardless of maternal age or newborn's birth weight.
Table 4: Risk of Instrumental Delivery among Nulliparous Women Related to Induction
Crude Odds
Ratio
Instrumental Vaginal Delivery 1.38
(1.19 - 1.59)*
*95% confidence interval
Adjusted for
Birth Weight
1.36
(1.17-1.57)*
Adjusted for
Maternal Age
1.38
(1.19 - 1.60)*
Adjusted for All
1.36
(1.18 - 1.58)*
Neonatal Characteristics
Neonatal characteristics at birth are presented in Table 5. The average neonatal weight at birth in the labor
induction group was 3,416 grams compared with 3,365 grams in the non-induced group (p