The association between the length of first stage of labor, mode of delivery, and perinatal outcomes in women undergoing induction of labor.

OBJECTIVE: To estimate the association between the lengths of the first stage of labor, mode of delivery, and perinatal outcomes in women undergoing labor induction. STUDY DESIGN: Retrospective cohort study of singleton, term pregnancies with labor induction and delivered during the second stage. The length of the first stage was examined by 6-hour intervals as predictors of mode of delivery and perinatal morbidity using chi(2) test and multivariable logistic regression analysis. RESULTS: There were 3620 women who met study criteria. Compared with women with a first stage between 0-12 hours, women with longer first stages had a higher risk of cesarean delivery during the second stage, up to an adjusted odds ratio of 7.44 in those with a first stage > or =24 hours (95% confidence interval [CI], 3.43-16.1). Women with a first stage > or =24 hours also had higher odds of postpartum hemorrhage (adjusted odds ratio [aOR], 3.16; 95% CI, 1.73-5.79), chorioamnionitis (aOR, 2.83; 95% CI, 1.19-6.69), and neonatal admission to the intensive care nursery (aOR, 2.03; 95% CI, 1.10-3.74). CONCLUSION: In women who underwent induction of labor, even when a second stage of labor was reached, the risk for cesarean delivery and maternal morbidity remained increased when the length of the first stage was longer than 24 hours. However, in this clinical scenario, the frequency of cesarean delivery remains less than 50%. The decision for surgical intervention thus should not be based on the elapse of time alone.

The use of ultrasound in fetal surgery.

Obstetric ultrasound (US) is an integral part of fetal surgery for open and minimally invasive techniques. With advances in US imaging, the ability to refine diagnosis, predict prognosis, and contribute to fetal treatment continues to grow. Current research in fetal diagnosis and treatment includes identifying the most reliable sonographic features for determining prognosis before and after surgery.

Does length of labor vary by maternal age?

OBJECTIVE: The purpose of this study was to examine lengths of first and second stages of labor across maternal age groups to determine whether different norms should be established. STUDY DESIGN: We conducted a retrospective cohort study of all laboring, term, singleton, and cephalic deliveries at a single institution between 1980-2001. Median lengths of labor were compared among 6 maternal age groups. Statistical comparisons were made using Kruskal-Wallis and Wilcoxon rank sum tests. Multivariable linear and logistic regression models were performed. RESULTS: Among 31,976 births, length of labor differed significantly by maternal age for both nulliparous and multiparous women. Younger nulliparous women (age, <20 yrs) had a shorter median second stage by up to 97 minutes (P < .001) than older nulliparous women (age, >39 yrs). After we controlled for potential confounders, we found that older women had a persistently higher likelihood of experiencing longer labor and prolonged labor than younger women. CONCLUSION: Length of labor and prolonged labor increases with increasing maternal age.

Duration of the second stage of labor in multiparous women: maternal and neonatal outcomes.

OBJECTIVE: This study was undertaken to examine perinatal outcomes associated with the second stage of labor in multiparous women. STUDY DESIGN: This is a retrospective cohort study of all term, cephalic, singleton births delivered by multiparous women between 1991 and 2001. Duration of the second stage of labor was stratified into hourly intervals: 0-1 hour, 1-2 hours, 2-3 hours, and 3 hours or longer. Perinatal outcomes were analyzed by using chi2 test and multivariable logistic regression models, by using P<.05 and 95% CI to indicate statistical significance. RESULTS: Compared with women who delivered between the 0- and 2-hour interval, women with a second stage more than 3 hours had higher risks of operative vaginal deliveries (odds ratio = 13.27; 95% CI [9.38-18.8]), cesarean deliveries (odds ratio = 6.00; [4.06-8.86]), and maternal morbidity including third- or fourth-degree perineal lacerations, postpartum hemorrhage, and chorioamnionitis. Their neonates had higher risks of 5-minute Apgar score less than 7 (odds ratio = 3.63; 95% CI [1.77-7.43]), meconium stained amniotic fluid (odds ratio = 1.44; 95% CI [1.07-1.94]), admission to intensive care nursery (odds ratio = 2.08; 95% CI [1.15-3.77]), composite neonatal morbidity (odds ratio = 1.85; 95% CI [1.23-2.77]), and longer neonatal stay in the hospital (odds ratio = 1.67; 95% CI [1.11-2.51]). CONCLUSION: Multiparous women with a second stage of 3 hours or greater are at increased risks for operative deliveries, peripartum morbidity, and undesirable neonatal outcomes. These outcomes should be considered in the management of multiparous women with a second stage of labor beyond 3 hours.

First-trimester combined screening: experience with an instant results approach.

OBJECTIVE: This study was undertaken to assess an instant results protocol for first-trimester combined screening. STUDY DESIGN: Retrospective analysis of patients having first-trimester combined screening between Nov. 1, 2003 and Oct. 31, 2005. We evaluated the feasibility of patient self-collection and mail-in of blood samples before nuchal translucency ultrasound. Primary outcome was success with providing in-office, immediate screening results after the ultrasound. Predictor variables included age, ethnicity, insurance, and provider. The chi2 analysis was performed. RESULTS: Two thousand three hundred ten women completed first-trimester combined screening, and 60.6% received instant results. When the biochemistry sample was collected at home, 80% received instant results. Age 35 years or older predicted instant results (P = .001), whereas ethnicity, insurance, and referring provider did not. Comparing the prior 24 months, clinic volume increased by 18%. Diagnostic procedure volume was unchanged, although chorionic villus sampling increased by 12% (P = .02) and amniocentesis decreased by 6% (P = .049). CONCLUSION: Patients were able to obtain instant results in 60.6% of cases, which appeared to increase the use of chorionic villus sampling.

Concordance of chart abstraction and patient recall of intrapartum variables up to 53 years later.

OBJECTIVE: The purpose of this study was to determine the concordance of patient recall compared with chart abstraction for distant intrapartum variables and to evaluate predictors of concordance. STUDY DESIGN: A random sample from a cohort of diverse women aged 40-74 years. Intrapartum variables reported by participants were compared with the medical record. Outcomes were assessed for sensitivity, specificity, positive predictive value, and negative predictive value. Multivariate logistic regression was used to determine predictors of concordance of patient recall. RESULTS: Four hundred one births among 178 women were analyzed. Recall of cesarean delivery had the highest concordance (sensitivity, 0.98; specificity, 1.00; positive predictive value, 1.00; negative predictive value, 0.99). Laceration that required repair had the lowest concordance (sensitivity, 0.37; specificity, 0.68; positive predictive value, 0.34; negative predictive value, 0.81). No variables predicted concordance of recall for all variables. CONCLUSION: The concordance of patient recall to chart abstraction for intrapartum variables varies widely, although with a pattern of greater specificity and negative predictive value of recall. This should be kept in mind during patient interviews and in the performance of clinical research.

Chorionic villus sampling compared with amniocentesis and the difference in the rate of pregnancy loss.

OBJECTIVE: To compare loss rates following amniocentesis and chorionic villus sampling (CVS) over time. METHODS: A retrospective cohort study of all amniocentesis and CVS procedures resulting in a normal karyotype from 1983-2003 at a single prenatal diagnostic referral center was conducted. Pregnancy loss rates for amniocentesis, CVS, and nonintervention groups (ie, those who had nuchal translucency screening or counseling, but no procedure) were compared using the chi 2 test. Year of procedure, maternal age, parity, race or ethnicity, and gestational age at procedure were controlled for in multivariable logistic regression models. RESULTS: There were 9,886 CVS and 30,893 amniocentesis procedures performed during the study period that resulted in a normal karyotype. The overall loss rates were 3.12% for CVS and 0.83% for amniocentesis (P < .001). When examined by 5-year intervals, there was a statistically significant decrease in the CVS loss rate (P < .001) and a nonsignificant lesser decrease in the loss rate for amniocentesis over time. Although the pregnancy loss rate from CVS over the entire study period was higher than from amniocentesis (adjusted odds ratio 4.23, 95% confidence interval 2.29-7.81), in the most recent time period, 1998 to 2003, there was no difference between the two procedures (adjusted odds ratio 1.03, 95% confidence interval 0.23-4.52). CONCLUSION: The loss rates for both amniocentesis and CVS at our institution have decreased over time. Because the decrease in loss rate for CVS has been greater, there is no longer a statistically significant difference between the two. These results are informative in both patient counseling and establishing widespread prenatal diagnostic and screening programs.

Gestational weight gain and adverse neonatal outcome among term infants.

OBJECTIVE: To examine the relationship between gestational weight gain and adverse neonatal outcomes among infants born at term (37 weeks or more). METHODS: This was a retrospective cohort study of 20,465 nondiabetic, term, singleton births. We performed univariable and multivariable analyses of the associations between gestational weight gain and neonatal outcomes. We categorized gestational weight gain by the Institute of Medicine guidelines as well as extremes of gestational weight gain (less than 7 kg and more than 18 kg). RESULTS: Gestational weight gain above the Institute of Medicine guidelines was more common than gestational weight gain below (43.3% compared with 20.1%). In multivariable analyses, gestational weight gain above guidelines was associated with a low 5-minute Apgar score (adjusted odds ratio [AOR] 1.33, 95% confidence interval [CI] 1.01-1.76), seizure (AOR 6.50, 95% CI 1.43-29.65), hypoglycemia (AOR 1.52, 95% CI 1.06-2.16), polycythemia (AOR 1.44, 95% CI 1.06-1.94), meconium aspiration syndrome (AOR 1.79, 95% CI 1.12-2.86), and large for gestational age (AOR 1.98, 95% CI 1.74-2.25) compared with women within weight gain guidelines. Gestational weight gain below guidelines was associated with decreased odds of neonatal intensive care unit admission (AOR 0.66, 95% CI 0.46-0.96) and increased odds of small for gestational age (SGA; AOR 1.66, 95% CI 1.44-1.92). Gestational weight gain less than 7 kg was associated with increased risk of seizure, hospital stay more than 5 days, and SGA. Gestational weight gain more than 18 kg was associated with assisted ventilation, seizure, hypoglycemia, polycythemia, meconium aspiration syndrome, and large for gestational age. CONCLUSION: Gestational weight gain above guidelines was common and associated with multiple adverse neonatal outcomes, whereas gestational weight gain below guidelines was only associated with SGA status. Public health efforts among similar populations should emphasize prevention of excessive gestational weight gain.

Are there ethnic differences in the length of labor?

OBJECTIVE: The purpose of this study was to examine the lengths of the first and second stages of labor among different racial/ethnic groups to determine whether different norms should be established. STUDY DESIGN: This was a retrospective cohort study of all laboring, term, singleton, vertex deliveries in a single academic institution. Median lengths of first and second stages of labor were compared among 4 racial/ethnic groups: black, Asian, white, and Latina. Kruskal-Wallis, Wilcoxon rank sum tests, and multivariate linear and logistic regression models were performed. RESULTS: In 27,521 births, the lengths of first stage of labor did not differ significantly among groups in the multivariate analysis. In the second stage of labor, black women had shorter labors, both overall and stratified by epidural use. In the multivariate analysis, when controlled for demographics, parity, epidural, chorioamnionitis, birthweight, delivery year, and labor management, black women had a shorter second stage than did white women (nulliparous women, 22 minutes; multiparous women, 7.5 minutes; P < .001) and lower rates of prolonged second stage (odds ratio, 0.6; P < .001). Nulliparous Asian women had a significantly longer second stage and higher rates of prolonged second stage, and nulliparous Latina women had a shorter second stage, compared with nulliparous white women. CONCLUSION: When data are controlled for confounding factors, black women had a shorter length of second stage of labor than did women in other ethnic groups. These differences appear to be clinically significant. This contributes to the support of a multifactorial redefinition of labor curves, which are used widely in the management of labor.

Racial/ethnic differences in perineal, vaginal and cervical lacerations.

OBJECTIVE: To determine if variation exists between ethnicities for risk of perineal, vaginal, and cervical laceration at vaginal delivery. STUDY DESIGN: Retrospective cohort study of nulliparous women who underwent vaginal delivery of a vertex presentation. Predictor variable was ethnicity with outcome variables cervical, vaginal, and second-, third-, or fourth-degree perineal laceration. Logistic regression analysis was conducted to control for confounders. RESULTS: Of the 17,216 who met criteria, Filipino (OR = 1.92, 95% CI 1.64-2.25) and Chinese (OR = 1.60, 95% CI 1.33-1.92) women were at greatest risk for third- and fourth-degree laceration. Only Filipino (OR = 1.32, 95% CI 1.10-1.57) and other Asian (OR = 1.23, 95% CI 1.08-1.41) women were at slightly increased risk of vaginal laceration. No differences were seen for cervical laceration. CONCLUSION: Different ethnicities are at widely varying risk of perineal laceration, but little difference exists for vaginal or cervical lacerations. Research into the mechanisms behind this should investigate differences in perineal anatomy.

How long is too long: Does a prolonged second stage of labor in nulliparous women affect maternal and neonatal outcomes?

OBJECTIVE: The purpose of this study was to examine maternal and neonatal outcomes in relation to lengthening intervals of the second stage of labor. STUDY DESIGN: This is a retrospective cohort study of 15,759 nulliparous, term, cephalic, singleton births at the University of California, San Francisco, between 1976 and 2001. The second stage of labor was divided into 1-hour intervals. Maternal and neonatal outcomes were compared with the use of chi-squared and Student t tests, and a probability value of < or =.05 was used to indicate statistical significance. Potential confounders were controlled for with multivariate logistic regression. RESULTS: Increasing rates of cesarean delivery, operative vaginal delivery, and perineal trauma were associated with the second stage beyond the first hour. In multivariate analysis, the >4-hour interval group had higher rates of cesarean delivery (odds ratio, 5.65; P < .001), operative vaginal deliveries (odds ratio, 2.83; P < .001), 3rd- or 4th-degree perineal lacerations (odds ratio, 1.33; P = .009), and chorioamnionitis (odds ratio, 1.79; P < .001). There were no differences in neonatal acid-base status associated with length of second stage. However, there were fewer neonates with a 5-minute Apgar score of <7 (odds ratio, 0.45; P = .01). CONCLUSION: Although the length of the second stage of labor is not associated with poor neonatal outcome, a prolonged second stage is associated with increased maternal morbidity and operative delivery rates.

Gestational weight gain, macrosomia, and risk of cesarean birth in nondiabetic nulliparas.

OBJECTIVE: To examine how the association between excessive weight gain and cesarean birth is modified by infant birth weight in nondiabetic women. METHODS: We designed a retrospective cohort study of singleton, term, nulliparous women with cephalic presentations delivering at a single university hospital. Subjects with diabetes were excluded. Bivariate and multivariate analyses were performed. Regression models controlled for maternal age, maternal prepregnancy body mass index, gestational age, ethnicity, smoking, birth weight, and date of delivery. RESULTS: Women gaining above Institute of Medicine guidelines were more likely to have a cesarean birth, even if birth weight was less than 4,000 g. In the multivariate analysis, women with excessive weight gain had an odds ratio of 1.40 (95% confidence interval 1.22-1.59) for cesarean birth. When absolute weight gain (total pregnancy weight gain minus birth weight and placental weight) was used in the multivariate analysis, excessive weight gain was still an independent predictor of cesarean delivery. Although macrosomia was a stronger predictor of cesarean than weight gain alone, excessive weight gain was much more common than macrosomia in our cohort. CONCLUSION: Excessive weight gain during pregnancy is an independent risk factor for cesarean birth, even when birth weight is not excessive. Other mechanisms besides macrosomia may be involved in the association between high weight gain and cesarean birth. We estimate that of the approximately 288,000 primary cesarean deliveries performed in nulliparas annually in the United States, 64,000 would be prevented if no women gained above Institute of Medicine recommendations. LEVEL OF EVIDENCE: II-2