Neonatal Mortality Risk for Repeat Cesarean Compared to Vaginal Birth after Cesarean (VBAC) Deliveries in the United States, 1998–2002 Birth Cohorts

Fay Menacker; Marian F. MacDorman; Eugene Declercq

Disclosures

Matern Child Health J. 2010;14(2):147-154. 

In This Article

Methods

Since 1989, data on method of delivery have been available through the U.S. Standard Certificate of a Live Birth. By 1991, all states and the District of Columbia were reporting information on this item. This paper examines the repeat cesarean section rate, defined here as the number of repeat cesareans per 100 live births to mothers who have had a previous cesarean and whose parity is known to be 2 or greater. We examine trends and characteristics of repeat cesareans to mothers in three groups: (1) all women; (2) those at low risk as defined by the American College of Obstetricians and Gynecologists (mothers with singleton, full term [37+ weeks] births in vertex presentation),[8] and (3) mothers at "no indicated risk"(NIR). A previous report used national U.S. birth certificate data to create this new category for analysis—mothers at "no indicated risk" and then examined the growth of primary cesareans in these cases from 1991–2001.[9] Births to women at NIR were singleton, term (37–41 weeks), vertex presentation births that were not reported to have any of 16 medical risk factors1 or 15 complications of labor/delivery2 listed on the 1989 revision of the U.S. Standard Certificate of Live Birth.

We then compared infant and neonatal mortality rates in repeat cesarean and vaginal birth after cesarean (VBAC) deliveries for low-risk and NIR births for the 1998–2002 birth cohorts, the latest national data available. To exclude post term deliveries which may have higher risks, in the mortality analysis (Tables 2, 3) infant gestational age of 37–41 weeks was used for births to low-risk women. After 2002, complete national data for the variables of interest were not available due to implementation of the 2003 Revision of the U.S. Standard Certificate of Live Birth.

Finally, multivariate logistic regression analysis was used to examine neonatal mortality for repeat cesareans and VBACs, after controlling for maternal age, race and Hispanic origin, parity, education, infant birthweight and gestational age. The parameters in the model were estimated by the maximum likelihood method using the LOGISTIC procedure of SAS, version 9.1.3.[10] Those records with missing data, (less than 4% of all records) were excluded from the models. All statements in the text were tested for statistical significance using the two-proportion z-test, and any differences noted as higher or lower were statistically significant.

1Anemia, cardiac disease, acute or chronic lung disease, diabetes, genital herpes, hydramnios/oligohydramnios, hemoglobinopathy, chronic hypertension, pregnancy associated hypertension, eclampsia, incompetent cervix, previous infant 4000 + grams, previous preterm or small small-for-gestational-age infant, renal disease, Rh sensitization, uterine bleeding.
2Febrile, meconium moderate/heavy, premature rupture of membrane, abruptio placenta, placenta previa, other excessive bleeding, seizures during labor, precipitous labor, prolonged labor, dysfunctional labor, breech/malpresentation, cephalopelvic disproportion, cord prolapse, anesthetic complication, fetal distress.

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