Daytime Compared With Nighttime Differences in Management and Outcomes of Postpartum Hemorrhage

OBJECTIVE

To assess whether postpartum hemorrhage management or subsequent morbidity differs based on whether delivery occurred during the day or night.

METHODS

We conducted a secondary analysis of a multicenter observational obstetric cohort of more than 115,000 mother-neonate pairs from 25 hospitals (2008-2011). This analysis included women delivering singleton or twin births who experienced postpartum hemorrhage (estimated blood loss greater than 500 cc for vaginal delivery, estimated blood loss greater than 1,000 cc for cesarean delivery, or documented treatment for postpartum hemorrhage). Nighttime delivery was defined as that occurring between 8 PM and 6 AM. The primary outcome was a composite of maternal morbidity (death, hysterectomy, intensive care unit admission, transfusion, or unanticipated procedure for bleeding). Secondary outcomes included estimated blood loss, uterotonic use, and procedures to treat bleeding that occurred during the postpartum hospitalization. Multivariable logistic, linear, quantile, and multinomial regression models were used to assess associations between nighttime delivery and outcomes, adjusting for potential patient-level confounders and hospital as a fixed effect.

RESULTS

In total, 2,709 (34.2%) of 7,917 women with postpartum hemorrhage delivered at night. Women who delivered at night were younger, had a lower body mass index, and were more likely to have government-sponsored insurance, be nulliparous, have hypertension, use neuraxial analgesia, and deliver vaginally. After adjusting for potential confounders, the primary composite outcome of maternal morbidity was similar regardless of night compared with day delivery (15.5% night vs 17.5% day; adjusted odds ratio 0.89, 95% CI 0.77-1.03). Some secondary outcomes, including mean EBL, frequency of uterotonic use, and time from delivery to first uterotonic dose, differed on unadjusted analyses, but these associations did not persist in multivariable analysis. The study had limited power to assess differences in uncommon outcomes.

CONCLUSION

Nighttime delivery was not associated with significant differences in postpartum hemorrhage-related management or morbidity.

Thyroid function in neonates of women with subclinical hypothyroidism or hypothyroxinemia

OBJECTIVE

To assess whether treatment of pregnant women with subclinical hypothyroidism or hypothyroxinemia alters neonatal TSH results.

STUDY DESIGN

A planned secondary analysis of data from two multi-center randomized, double-masked, placebo-controlled thyroxine replacement trials in pregnant women with either subclinical hypothyroidism or hypothyroxinemia. Infant heel-stick specimens were obtained before discharge. We compared TSH levels between neonates born to mothers allocated to treatment or placebo within each trial and between neonates in the placebo groups. Multiples of means were generated for day-of-life-specific data.

RESULTS

Neonatal TSH values were available for 573/677 (84.6%) newborns from the subclinical hypothyroidism trial and 461/526 (87.6%) newborns from the hypothyroxinemia trial. Neonatal TSH values did not differ in either trial by treatment group or between placebo groups (P > 0.05 for all comparisons).

CONCLUSIONS

Neonatal TSH values did not differ with thyroid hormone replacement in pregnancies diagnosed with subclinical hypothyroidism or hypothyroxinemia.

Incidence of early-onset sepsis in infants born to women with clinical chorioamnionitis

Objective To determine the frequency of sepsis and other adverse neonatal outcomes in women with a clinical diagnosis of chorioamnionitis. Methods We performed a secondary analysis of a multi-center placebo-controlled trial of vitamins C/E to prevent preeclampsia in low risk nulliparous women. Clinical chorioamnionitis was defined as either the "clinical diagnosis" of chorioamnionitis or antibiotic administration during labor because of an elevated temperature or uterine tenderness in the absence of another cause. Early-onset neonatal sepsis was categorized as "suspected" or "confirmed" based on a clinical diagnosis with negative or positive blood, urine or cerebral spinal fluid cultures, respectively, within 72 h of birth. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by logistic regression. Results Data from 9391 mother-infant pairs were analyzed. The frequency of chorioamnionitis was 10.3%. Overall, 6.6% of the neonates were diagnosed with confirmed (0.2%) or suspected (6.4%) early-onset sepsis. Only 0.7% of infants born in the setting of chorioamnionitis had culture-proven early-onset sepsis versus 0.1% if chorioamnionitis was not present. Clinical chorioamnionitis was associated with both suspected [OR 4.01 (3.16-5.08)] and confirmed [OR 4.93 (1.65-14.74)] early-onset neonatal sepsis, a need for resuscitation within the first 30 min after birth [OR 2.10 (1.70-2.61)], respiratory distress [OR 3.14 (2.16-4.56)], 1 min Apgar score of ≤3 [OR 2.69 (2.01-3.60)] and 4-7 [OR 1.71 (1.43-2.04)] and 5 min Apgar score of 4-7 [OR 1.67 (1.17-2.37)] (vs. 8-10). Conclusion Clinical chorioamnionitis is common and is associated with neonatal morbidities. However, the vast majority of exposed infants (99.3%) do not have confirmed early-onset sepsis.

Association Between Gestational Weight Gain and Perinatal Outcomes

OBJECTIVE

To evaluate the association between gestational weight gain and maternal and neonatal outcomes in a large, geographically diverse cohort.

METHODS

Trained chart abstractors at 25 hospitals obtained maternal and neonatal data for all deliveries on randomly selected days over 3 years (2008-2011). Gestational weight gain was derived using weight at delivery minus prepregnancy or first-trimester weight and categorized as below, within, or above the Institute of Medicine (IOM) guidelines in this retrospective cohort study. Maternal (primary or repeat cesarean delivery, third- or fourth-degree lacerations, severe postpartum hemorrhage, hypertensive disease of pregnancy) and neonatal (preterm birth, shoulder dystocia, macrosomia, hypoglycemia) outcomes were compared among women in the gestational weight gain categories in unadjusted and adjusted analyses with odds ratios (ORs) and 95% CI reported. Covariates included age, race-ethnicity, tobacco use, insurance type, parity, prior cesarean delivery, pregestational diabetes, hypertension, and hospital type.

RESULTS

Of the 29,861 women included, 51% and 21% had gestational weight gain above and below the guidelines, respectively. There was an association between gestational weight gain above the IOM guidelines and cesarean delivery in both nulliparous women (adjusted OR 1.44, 95% CI 1.31-1.59) and multiparous women (adjusted OR 1.26, 95% CI 1.13-1.41) and hypertensive diseases of pregnancy in nulliparous and multiparous women combined (adjusted OR 1.84, 95% CI 1.66-2.04). For the neonatal outcomes, gestational weight gain above the IOM guidelines was associated with shoulder dystocia (adjusted OR 1.74, 95% CI 1.41-2.14), macrosomia (adjusted OR 2.66, 95% CI 2.03-3.48), and neonatal hypoglycemia (adjusted OR 1.60, 95% CI 1.16-2.22). Gestational weight gain below the guidelines was associated with spontaneous (adjusted OR 1.50, 95% CI 1.31-1.73) and indicated (adjusted OR 1.34, 95% CI 1.12-1.60) preterm birth.

CONCLUSION

In a large, diverse cohort with prospectively collected data, gestational weight gain below or above guidelines is associated with a variety of adverse pregnancy outcomes.

Stillbirth, Inflammatory Markers, and Obesity: Results from the Stillbirth Collaborative Research Network

BACKGROUND

Obesity is associated with increased risk of stillbirth, although the mechanisms are unknown. Obesity is also associated with inflammation. Serum ferritin, C-reactive protein, white blood cell count, and histologic chorioamnionitis are all markers of inflammation.

OBJECTIVE

This article determines if inflammatory markers are associated with stillbirth and body mass index (BMI). Additionally, we determined whether inflammatory markers help to explain the known relationship between obesity and stillbirth.

STUDY DESIGN

White blood cell count was assessed at admission to labor and delivery, maternal serum for assessment of various biomarkers was collected after study enrollment, and histologic chorioamnionitis was based on placental histology. These markers were compared for stillbirths and live births overall and within categories of BMI using analysis of variance on logarithmic-transformed markers and logistic regression for dichotomous variables. The impact of inflammatory markers on the association of BMI categories with stillbirth status was assessed using crude and adjusted odds ratios (COR and AOR, respectively) from logistic regression models. The interaction of inflammatory markers and BMI categories on stillbirth status was also assessed through logistic regression. Additional logistic regression models were used to determine if the association of maternal serum ferritin with stillbirth is different for preterm versus term births. Analyses were weighted for the overall population from which this sample was derived.

RESULTS

A total of 497 women with singleton stillbirths and 1,414 women with live births were studied with prepregnancy BMI (kg/m²) categorized as normal (18.5-24.9), overweight (25.0-29.9), or obese (30.0 + ). Overweight (COR, 1.48; 95% confidence interval [CI]: 1.14-1.94) and obese women (COR, 1.60; 95% CI: 1.23-2.08) were more likely than normal weight women to experience stillbirth. Serum ferritin levels were higher (geometric mean: 37.4 ng/mL vs. 23.3, p < 0.0001) and C-reactive protein levels lower (geometric mean: 2.9 mg/dL vs. 3.3, p = 0.0279), among women with stillbirth compared with live birth. Elevated white blood cell count (15.0 uL × 10³ or greater) was associated with stillbirth (21.2% SB vs. 10.0% live birth, p < 0.0001). Histologic chorioamnionitis was more common (33.2% vs. 15.7%, p < 0.0001) among women with stillbirth compared with those with live birth. Serum ferritin, C-reactive protein, and chorioamnionitis had little impact on the ORs associating stillbirth with overweight or obesity. Adjustment for elevated white blood cell count did not meaningfully change the OR for stillbirth in overweight versus normal weight women. However, the stillbirth OR for obese versus normal BMI changed by more than 10% when adjusting for histologic chorioamnionitis (AOR, 1.38; 95% CI: 1.02-1.88), indicating confounding. BMI by inflammatory marker interaction terms were not significant. The association of serum ferritin levels with stillbirth was stronger among preterm births (p = 0.0066).

CONCLUSION

Maternal serum ferritin levels, elevated white blood cell count, and histologic chorioamnionitis were positively and C-reactive protein levels negatively associated with stillbirth. Elevated BMIs, both overweight and obese, were associated with stillbirth when compared with women with normal BMI. None of the inflammatory markers fully accounted for the relationship between obesity and stillbirth. The association of maternal serum ferritin with stillbirth was stronger in preterm than term stillbirths.

Neonatal outcomes of elective early-term births after demonstrated fetal lung maturity

BACKGROUND

Studies of early-term birth after demonstrated fetal lung maturity show that respiratory and other outcomes are worse with early-term birth (370-386 weeks) even after demonstrated fetal lung maturity when compared with full-term birth (390-406 weeks). However, these studies included medically indicated births and are therefore potentially limited by confounding by the indication for delivery. Thus, the increase in adverse outcomes might be due to the indication for early-term birth rather than the early-term birth itself.

OBJECTIVE

We examined the prevalence and risks of adverse neonatal outcomes associated with early-term birth after confirmed fetal lung maturity as compared with full-term birth in the absence of indications for early delivery.

STUDY DESIGN

This is a secondary analysis of an observational study of births to 115,502 women in 25 hospitals in the United States from 2008 through 2011. Singleton nonanomalous births at 37-40 weeks with no identifiable indication for delivery were included; early-term births after positive fetal lung maturity testing were compared with full-term births. The primary outcome was a composite of death, ventilator for ≥2 days, continuous positive airway pressure, proven sepsis, pneumonia or meningitis, treated hypoglycemia, hyperbilirubinemia (phototherapy), and 5-minute Apgar <7. Logistic regression and propensity score matching (both 1:1 and 1:2) were used.

RESULTS

In all, 48,137 births met inclusion criteria; the prevalence of fetal lung maturity testing in the absence of medical or obstetric indications for early delivery was 0.52% (n = 249). There were 180 (0.37%) early-term births after confirmed pulmonary maturity and 47,957 full-term births. Women in the former group were more likely to be non-Hispanic white, smoke, have received antenatal steroids, have induction, and have a cesarean. Risks of the composite (16.1% vs 5.4%; adjusted odds ratio, 3.2; 95% confidence interval, 2.1-4.8 from logistic regression) were more frequent with elective early-term birth. Propensity scores matching confirmed the increased primary composite in elective early-term births: adjusted odds ratios, 4.3 (95% confidence interval, 1.8-10.5) for 1:1 and 3.5 (95% confidence interval, 1.8-6.5) for 1:2 matching. Among components of the primary outcome, CPAP use and hyperbilirubinemia requiring phototherapy were significantly increased. Transient tachypnea of the newborn, neonatal intensive care unit admission, and prolonged neonatal intensive care unit stay (>2 days) were also increased with early-term birth.

CONCLUSION

Even with confirmed pulmonary maturity, early-term birth in the absence of medical or obstetric indications is associated with worse neonatal respiratory and hepatic outcomes compared with full-term birth, suggesting relative immaturity of these organ systems in early-term births.

Comparison of diameter-based and image-based measures of surface area from gross placental pathology for use in epidemiologic studies

Placental surface area is often estimated using diameter measurements. However, as many placentas are not elliptical, we were interested in the validity of these estimates. We compared placental surface area from images for 491 singletons from the Stillbirth Collaborative Research Network (SCRN) Study (416 live births, 75 stillbirths) to estimates obtained using diameter measurements. Placental images and diameters were obtained from pathologic assessments conducted for the SCRN Study and images were analyzed using ImageJ software. On average, diameter-based measures underestimated surface area by -5.58% (95% confidence interval: -30.23, 19.07); results were consistent for normal and abnormal shapes. The association between surface area and birthweight was similar for both measures. Thus, diameter-based surface area can be used to estimate placental surface area.

Long-term mortality risk and life expectancy following recurrent hypertensive disease of pregnancy

BACKGROUND

Women with a history of hypertensive disease of pregnancy have increased risks for early mortality from multiple causes. The effect of recurrent hypertensive disease of pregnancy on mortality risk and life expectancy is unknown.

OBJECTIVE

We sought to determine whether recurrent hypertensive disease of pregnancy is associated with increased mortality risks.

STUDY DESIGN

In this retrospective cohort study, we used birth certificate data to determine the number of pregnancies affected by hypertensive disease of pregnancy for each woman delivering in Utah from 1939 through 2012. We assigned women to 1 of 3 groups based on number of affected pregnancies: 0, 1, or ≥2. Exposed women had ≥1 affected singleton pregnancy and lived in Utah for ≥1 year postpartum. Exposed women were matched 1:2 to unexposed women by age, year of childbirth, and parity. Underlying cause of death was determined from death certificates. Mortality risks by underlying cause of death were compared between exposed and unexposed women as a function of number of affected pregnancies. Cox regressions controlled for infant sex, gestational age, parental education, ethnicity, and marital status.

RESULTS

We identified 57,384 women with ≥1 affected pregnancy (49,598 women with 1 affected pregnancy and 7786 women with ≥2 affected pregnancies). These women were matched to 114,768 unexposed women. As of 2016, 11,894 women were deceased: 4722 (8.2%) exposed and 7172 (6.3%) unexposed. Women with ≥2 affected pregnancies had increased mortality from all causes (adjusted hazard ratio, 2.04; 95% confidence interval, 1.76-2.36), diabetes (adjusted hazard ratio, 4.33; 95% confidence interval, 2.21-8.47), ischemic heart disease (adjusted hazard ratio, 3.30; 95% confidence interval, 2.02-5.40), and stroke (adjusted hazard ratio, 5.10; 95% confidence interval, 2.62-9.92). For women whose index pregnancy delivered from 1939 through 1959 (n = 10,488), those with ≥2 affected pregnancies had shorter additional life expectancies than mothers who had only 1 or 0 hypertensive pregnancies (48.92 vs 51.91 vs 55.48 years, respectively).

CONCLUSION

Hypertensive diseases of pregnancy are associated with excess risks for early all-cause mortality and some cause-specific mortality, and these risks increase further with recurrent disease.

Adverse Maternal and Neonatal Outcomes in Indicated Compared with Spontaneous Preterm Birth in Healthy Nulliparas: A Secondary Analysis of a Randomized Trial

OBJECTIVE

To compare the risks of adverse maternal and neonatal outcomes associated with spontaneous (SPTB) versus indicated preterm births (IPTB).

METHODS

A secondary analysis of a multicenter trial of vitamin C and E supplementation in healthy low-risk nulliparous women. Outcomes were compared between women with SPTB (due to spontaneous membrane rupture or labor) and those with IPTB (due to medical or obstetric complications). A primary maternal composite outcome included: death, pulmonary edema, blood transfusion, adult respiratory distress syndrome (RDS), cerebrovascular accident, acute tubular necrosis, disseminated intravascular coagulopathy, or liver rupture. A neonatal composite outcome included: neonatal death, RDS, grades III or IV intraventricular hemorrhage (IVH), sepsis, necrotizing enterocolitis (NEC), or retinopathy of prematurity.

RESULTS

Of 9,867 women, 10.4% (N = 1,038) were PTBs; 32.7% (n = 340) IPTBs and 67.3% (n = 698) SPTBs. Compared with SPTB, the composite maternal outcome was more frequent in IPTB-4.4% versus 0.9% (adjusted odds ratio [aOR], 4.0; 95% confidence interval [CI], 1.4-11.8), as were blood transfusion and prolonged hospital stay (3.2 and 3.7 times, respectively). The frequency of composite neonatal outcome was higher in IPTBs (aOR, 1.8; 95% CI, 1.1-3.0), as were RDS (1.7 times), small for gestational age (SGA) < 5th percentile (7.9 times), and neonatal intensive care unit (NICU) admission (1.8 times).

CONCLUSION

Adverse maternal and neonatal outcomes were significantly more likely with IPTB than with SPTB.

Variation in the Nulliparous, Term, Singleton, Vertex Cesarean Delivery Rate

OBJECTIVE

To estimate the contributions of patient and health care provider-hospital characteristics to the variation in the frequency of nulliparous, term, singleton, vertex cesarean delivery in a multi-institutional U.S. cohort.

METHODS

We performed a secondary analysis of the multicenter Assessment of Perinatal Excellence cohort of 115,502 mother and neonatal pairs who were delivered at 25 hospitals between March 2008 and February 2011. Women met inclusion criteria if they were nulliparous and delivered a singleton in vertex presentation at term. Hospital ranks for nulliparous, term, singleton, vertex cesarean delivery frequency were determined after risk adjustment. The fraction of variation in nulliparous, term, singleton, vertex cesarean delivery frequency attributable to patient and health care provider-hospital characteristics was assessed using hierarchical logistic regression.

RESULTS

Of the 115,502 deliveries in the initial cohort, 38,275 nulliparous, term, singleton, vertex deliveries met inclusion criteria. The median hospital nulliparous, term, singleton, vertex cesarean delivery frequency was 25.3% with a range from 15.0% to 35.2%. The majority of hospitals (16/25) changed rank quintiles after risk adjustment; overall the changes in rank were not statistically significant (P=.53). Patient characteristics accounted for 24% of the nulliparous, term, singleton, vertex cesarean delivery variation. The analyzed health care provider-hospital characteristics were not significantly associated with cesarean delivery frequency.

CONCLUSION

Although patient characteristics accounted for some of the variation in nulliparous, term, singleton, vertex cesarean delivery frequency and accounting for case mix had implications for hospital cesarean delivery rankings, the majority of the variation was not explained by the characteristics evaluated. These findings emphasize the importance of continued efforts to understand aspects of obstetric care, including case mix, that contribute to cesarean delivery variation.

The Association of Decision-to-Incision Time for Cesarean Delivery with Maternal and Neonatal Outcomes

OBJECTIVE

The objective of this study was to estimate whether the decision-to-incision (DTI) time for cesarean delivery (CD) is associated with differences in maternal and neonatal outcomes.

METHODS

This analysis is of data from women at 25 U.S. medical centers with a term, singleton, cephalic nonanomalous gestation and no prior CD, who underwent an intrapartum CD. Perinatal and maternal outcomes associated with DTI intervals of ≤ 15, 16 to 30, and > 30 minutes were compared.

RESULTS

Among 3,482 eligible women, median DTI times were 46 and 27 minutes for arrest and fetal indications for CD, respectively (p < 0.01). Women with a fetal indication whose DTI interval was > 30 minutes had similar odds to the referent group (DTI of 16-30 minutes) for the adverse neonatal and maternal composites (odds ratio [OR]: 0.83, 95% confidence interval [CI]: 0.40-1.71 and OR: 0.89, 95% CI: 0.63-1.27). For arrest disorders, the odds of the adverse neonatal composite were lower among women with a DTI of > 30 minutes (OR: 0.25, 95% CI: 0.08-0.77), and the adverse maternal composite was no different (OR: 1.15, 95% CI: 0.81-1.63).

CONCLUSION

In this analysis, DTI times longer than 30 minutes were not associated with worse maternal or neonatal outcomes.

Pregnancy-Associated Hypertension and Offspring Cardiometabolic Health

OBJECTIVE

To evaluate whether pregnancy-associated hypertension (gestational hypertension and preeclampsia) was associated with the cardiometabolic health of young offspring.

METHODS

This was a prospective observational follow-up study from 2012 to 2013 of children born to women previously enrolled in a mild gestational diabetes mellitus treatment trial or nongestational diabetes mellitus observational study. At 5-10 years after birth, children were examined and fasting blood samples obtained to determine the following cardiometabolic risk factors: blood pressure (BP), high-density lipoprotein cholesterol, triglycerides, glucose, homeostatic model assessment of insulin resistance, waist circumference, and body mass index (BMI).

RESULTS

This analysis included 979 children evaluated at a median 7 years of age. Twenty-three (2%) were born preterm from a hypertensive pregnancy, 73 (7%) were born at term from a hypertensive pregnancy, 58 (6%) were born preterm from a normotensive pregnancy, and 825 (84%) were born at term from a normotensive pregnancy (reference group). After adjusting for confounding factors, mean adjusted systolic BP was significantly higher in the children who were born at term to mothers who experienced pregnancy-associated hypertension compared with those born at term to normotensive mothers (systolic BP of 104 mm Hg, 95% CI 101-106 vs systolic BP of 99 mm Hg, 95% CI 99-100, P=.001). No other significant differences were observed.

CONCLUSION

Pregnancy-associated hypertension in women who deliver at term was associated with higher systolic BP in the offspring, but not with their measures of diastolic BP, BMI, waist circumference, homeostatic model assessment of insulin resistance, glucose, or lipids.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT00069576.

Potentially Preventable Stillbirth in a Diverse U.S. Cohort

OBJECTIVE

To estimate the proportion of potentially preventable stillbirths in the United States.

METHODS

We conducted a secondary analysis of 512 stillbirths with complete evaluation enrolled in the Stillbirth Collaborative Research Network from 2006 to 2008. The Stillbirth Collaborative Research Network was a multisite, geographically, racially, and ethnically diverse, population-based case-control study of stillbirth in the United States. Cases of stillbirth underwent standard evaluation that included maternal interview, medical record abstraction, biospecimen collection, postmortem examination, placental pathology, and clinically recommended evaluation. Each stillbirth was assigned probable and possible causes of death using the Initial Causes of Fetal Death algorithm system. For this analysis, we defined potentially preventable stillbirths as those occurring in nonanomalous fetuses, 24 weeks of gestation or greater, and weighing 500 g or greater that were 1) intrapartum, 2) the result of medical complications, 3) the result of placental insufficiency, 4) multiple gestation (excluding twin-twin transfusion), 5) the result of spontaneous preterm birth, or 6) the result of hypertensive disorders of pregnancy.

RESULTS

Of the 512 stillbirths included in our cohort, causes of potentially preventable stillbirth included placental insufficiency (65 [12.7%]), medical complications of pregnancy (31 [6.1%]), hypertensive disorders of pregnancy (20 [3.9%]), preterm labor (16 [3.1%]), intrapartum (nine [1.8%]), and multiple gestations (four [0.8%]). Twenty-seven stillbirths fit two or more categories, leaving 114 (22.3%) potentially preventable stillbirths.

CONCLUSION

Based on our definition, almost one fourth of stillbirths are potentially preventable. Given the predominance of placental insufficiency among stillbirths, identification and management of placental insufficiency may have the most immediate effect on stillbirth reduction.

Defining failed induction of labor

BACKGROUND

While there are well-accepted standards for the diagnosis of arrested active-phase labor, the definition of a "failed" induction of labor remains less certain. One approach to diagnosing a failed induction is based on the duration of the latent phase. However, a standard for the minimum duration that the latent phase of a labor induction should continue, absent acute maternal or fetal indications for cesarean delivery, remains lacking.

OBJECTIVE

The objective of this study was to determine the frequency of adverse maternal and perinatal outcomes as a function of the duration of the latent phase among nulliparous women undergoing labor induction.

STUDY DESIGN

This study is based on data from an obstetric cohort of women delivering at 25 US hospitals from 2008 through 2011. Nulliparous women who had a term singleton gestation in the cephalic presentation were eligible for this analysis if they underwent a labor induction. Consistent with prior studies, the latent phase was determined to begin once cervical ripening had ended, oxytocin was initiated, and rupture of membranes had occurred, and was determined to end once 5-cm dilation was achieved. The frequencies of cesarean delivery, as well as of adverse maternal (eg, postpartum hemorrhage, chorioamnionitis) and perinatal (eg, a composite frequency of seizures, sepsis, bone or nerve injury, encephalopathy, or death) outcomes, were compared as a function of the duration of the latent phase (analyzed with time both as a continuous measure and categorized in 3-hour increments).

RESULTS

A total of 10,677 women were available for analysis. In the vast majority (96.4%) of women, the active phase had been reached by 15 hours. The longer the duration of a woman's latent phase, the greater her chance of ultimately undergoing a cesarean delivery (P < .001, for time both as a continuous and categorical independent variable), although >40% of women whose latent phase lasted ≥18 hours still had a vaginal delivery. Several maternal morbidities, such as postpartum hemorrhage (P < .001) and chorioamnionitis (P < .001), increased in frequency as the length of latent phase increased. Conversely, the frequencies of most adverse perinatal outcomes were statistically stable over time.

CONCLUSION

The large majority of women undergoing labor induction will have entered the active phase by 15 hours after oxytocin has started and rupture of membranes has occurred. Maternal adverse outcomes become statistically more frequent with greater time in the latent phase, although the absolute increase in frequency is relatively small. These data suggest that cesarean delivery should not be undertaken during the latent phase prior to at least 15 hours after oxytocin and rupture of membranes have occurred. The decision to continue labor beyond this point should be individualized, and may take into account factors such as other evidence of labor progress.

Predictive Characteristics of Elevated 1-Hour Glucose Challenge Test Results for Gestational Diabetes

Objective The objective was to estimate the optimal screen-positive 1-hour 50 g glucose challenge test (GCT) threshold for gestational diabetes (GDM) and predictive characteristics of increasing screen-positive GCT threshold values (135–199 mg/dL) for GDM.

Study Design It is a secondary analysis of a multicenter mild GDM study. At 24 to 30 weeks' gestation, women with elevated GCT (135–199 mg/dL) completed a diagnostic 3-hour oral glucose tolerance test (OGTT). A novel change-point analysis method was used to compare the GDM rates for the adjacent GCT values, delineating categories of changing risk such that values within categories have equal risk for GDM. Positive (PPV) and negative (NPV) predictive values for GDM were computed for increasing GCT cut-offs.

Results In 7,280 women with both GCT (135–199 mg/dL) and OGTT results, 4 GDM risk-equivalent GCT categories were identified with escalations at 144, 158, and 174 mg/dL (all p-values <0.05). The PPV for GDM increased from 33 to 64% as GCT increased from 135 to 199 mg/dL, while the NPV decreased from 80 to 67%. PPVs were only 20% and 61% for risk-equivalent categories of 135 to 143 mg/dL and 174 to 199 mg/dL, respectively.

Conclusion Elevated GCT cut-off values between 135 and 143 mg/dL may carry equivalent GDM risk. No threshold GCT value <199 mg/dL alone sufficiently predicts GDM.

Racial and Ethnic Differences in Utilization of Labor Management Strategies Intended to Reduce Cesarean Delivery Rates

OBJECTIVE

To examine whether racial and ethnic differences exist in the frequency of and indications for cesarean delivery and to assess whether application of labor management strategies intended to reduce cesarean delivery rates is associated with patient's race and ethnicity.

METHODS

This is a secondary analysis of a multicenter observational obstetric cohort. Trained research personnel abstracted maternal and neonatal records of greater than 115,000 pregnant women from 25 hospitals (2008-2011). Women at term with singleton, nonanomalous, vertex, liveborn neonates were included in two cohorts: 1) nulliparous women (n=35,529); and 2) multiparous women with prior vaginal deliveries only (n=39,871). Women were grouped as non-Hispanic black, non-Hispanic white, Hispanic, and Asian. Multivariable logistic regression was used to evaluate the following outcomes: overall cesarean delivery frequency, indications for cesarean delivery, and utilization of labor management strategies intended to safely reduce cesarean delivery.

RESULTS

A total of 75,400 women were eligible for inclusion, of whom 47% (n=35,529) were in the nulliparous cohort and 53% (n=39,871) were in the multiparous cohort. The frequencies of cesarean delivery were 25.8% among nulliparous women and 6.0% among multiparous women. For nulliparous women, the unadjusted cesarean delivery frequencies were 25.0%, 28.3%, 28.7%, and 24.0% for non-Hispanic white, non-Hispanic black, Asian, and Hispanic women, respectively. Among nulliparous women, the adjusted odds of cesarean delivery were higher in all racial and ethnic groups compared with non-Hispanic white women (non-Hispanic black adjusted odds ratio [OR] 1.47, 95% CI 1.36-1.59; Asian adjusted OR 1.26, 95% CI 1.14-1.40; Hispanic adjusted OR 1.17, 95% CI 1.07-1.27) as a result of greater odds of cesarean delivery both for nonreassuring fetal status and labor dystocia. Nonapplication of labor management strategies regarding failed induction, arrest of dilation, arrest of descent, or cervical ripening did not contribute to increased odds of cesarean delivery for non-Hispanic black and Hispanic women. Compared with non-Hispanic white women, Hispanic women were actually less likely to experience elective cesarean delivery (adjusted OR 0.60, 95% CI 0.42-0.87) or cesarean delivery for arrest of dilation before 4 hours (adjusted OR 0.67, 95% CI 0.49-0.92). Additionally, compared with non-Hispanic white women, Asian women were more likely to experience cesarean delivery for nonreassuring fetal status (adjusted OR 1.29, 95% CI 1.09-1.53) and to have had that cesarean delivery be performed in the setting of a 1-minute Apgar score 7 or greater (adjusted OR 1.79, 95% CI 1.07-3.00). A similar trend was seen among multiparous women with prior vaginal deliveries.

CONCLUSION

Although racial and ethnic disparities exist in the frequency of cesarean delivery, differential use of labor management strategies intended to reduce the cesarean delivery rate does not appear to be associated with these racial and ethnic disparities.

The association among cytochrome P450 3A, progesterone receptor polymorphisms, plasma 17-alpha hydroxyprogesterone caproate concentrations, and spontaneous preterm birth

BACKGROUND

Infants born <37 weeks' gestation are of public health concern since complications associated with preterm birth are the leading cause of mortality in children <5 years of age and a major cause of morbidity and lifelong disability. The administration of 17-alpha hydroxyprogesterone caproate reduces preterm birth by 33% in women with history of spontaneous preterm birth. We demonstrated previously that plasma concentrations of 17-alpha hydroxyprogesterone caproate vary widely among pregnant women and that women with 17-alpha hydroxyprogesterone caproate plasma concentrations in the lowest quartile had spontaneous preterm birth rates of 40% vs rates of 25% in those women with higher concentrations. Thus, plasma concentrations are an important factor in determining drug efficacy but the reason 17-alpha hydroxyprogesterone caproate plasma concentrations vary so much is unclear. Predominantly, 17-alpha hydroxyprogesterone caproate is metabolized by CYP3A4 and CYP3A5 enzymes.

OBJECTIVE

We sought to: (1) determine the relation between 17-alpha hydroxyprogesterone caproate plasma concentrations and single nucleotide polymorphisms in CYP3A4 and CYP3A5; (2) test the association between progesterone receptor single nucleotide polymorphisms and spontaneous preterm birth; and (3) test whether the association between plasma concentrations of 17-alpha hydroxyprogesterone caproate and spontaneous preterm birth varied by progesterone receptor single nucleotide polymorphisms.

STUDY DESIGN

In this secondary analysis, we evaluated genetic polymorphism in 268 pregnant women treated with 17-alpha hydroxyprogesterone caproate, who participated in a placebo-controlled trial to evaluate the benefit of omega-3 supplementation in women with history of spontaneous preterm birth. Trough plasma concentrations of 17-alpha hydroxyprogesterone caproate were measured between 25-28 weeks of gestation after a minimum of 5 injections of 17-alpha hydroxyprogesterone caproate. We extracted DNA from maternal blood samples and genotyped the samples using TaqMan (Applied Biosystems, Foster City, CA) single nucleotide polymorphism genotyping assays for the following single nucleotide polymorphisms: CYP3A4*1B, CYP3A4*1G, CYP3A4*22, and CYP3A5*3; and rs578029, rs471767, rs666553, rs503362, and rs500760 for progesteronereceptor. We adjusted for prepregnancy body mass index, race, and treatment group in a multivariable analysis. Differences in the plasma concentrations of 17-alpha hydroxyprogesterone caproate by genotype were evaluated for each CYP single nucleotide polymorphism using general linear models. The association between progesterone receptor single nucleotide polymorphisms and frequency of spontaneous preterm birth was tested using logistic regression. A logistic model also tested interaction between 17-alpha hydroxyprogesterone caproate concentrations with each progesterone receptor single nucleotide polymorphism for the outcome of spontaneous preterm birth.

RESULTS

The association between CYP single nucleotide polymorphisms *22, *1G, *1B, and *3 and trough plasma concentrations of 17-alpha hydroxyprogesterone caproate was not statistically significant (P = .68, .44, .08, and .44, respectively). In an adjusted logistic regression model, progesterone receptor single nucleotide polymorphisms rs578029, rs471767, rs666553, rs503362, and rs500760 were not associated with the frequency of spontaneous preterm birth (P = .29, .10, .76, .09, and .43, respectively). Low trough plasma concentrations of 17-alpha hydroxyprogesterone caproate were statistically associated with a higher frequency of spontaneous preterm birth (odds ratio, 0.78; 95% confidence ratio, 0.61-0.99; P = .04 for trend across quartiles), however no significant interaction with the progesterone receptor single nucleotide polymorphisms rs578029, rs471767, rs666553, rs503362, and rs500760 was observed (P = .13, .08, .10, .08, and .13, respectively).

CONCLUSION

The frequency of recurrent spontaneous preterm birth appears to be associated with trough 17-alpha hydroxyprogesterone caproate plasma concentrations. However, the wide variation in trough 17-alpha hydroxyprogesterone caproate plasma concentrations is not attributable to polymorphisms in CYP3A4 and CYP3A5 genes. Progesterone receptor polymorphisms do not predict efficacy of 17-alpha hydroxyprogesterone caproate. The limitations of this secondary analysis include that we had a relative small sample size (n = 268) and race was self-reported by the patients.