Genetic Predisposition to Adverse Neurodevelopmental Outcome of Extremely Low Birth Weight Infants.

OBJECTIVE: This study aimed to evaluate whether there are genetic variants associated with adverse neurodevelopmental outcomes in extremely low birth weight (ELBW) infants. STUDY DESIGN: We conducted a candidate gene association study in two well-defined cohorts of ELBW infants (<1,000 g). One cohort was for discovery and the other for replication. The discovery case-control analysis utilized anonymized DNA samples and evaluated 1,614 single-nucleotide polymorphisms (SNPs) in 145 genes concentrated in inflammation, angiogenesis, brain development, and oxidation pathways. Cases were children who died by age one or who were diagnosed with cerebral palsy (CP) or neurodevelopmental delay (Bayley II mental developmental index [MDI] or psychomotor developmental index [PDI] < 70) by 18 to 22 months. Controls were survivors with normal neurodevelopment. We assessed significant epidemiological variables and SNPs associated with the combined outcome of CP or death, CP, mental delay (MDI < 70) and motor delay (PDI < 70). Multivariable analyses adjusted for gestational age at birth, small for gestational age, sex, antenatal corticosteroids, multiple gestation, racial admixture, and multiple comparisons. SNPs associated with adverse neurodevelopmental outcomes with p < 0.01 were selected for validation in the replication cohort. Successful replication was defined as p < 0.05 in the replication cohort. RESULTS: Of 1,013 infants analyzed (452 cases, 561 controls) in the discovery cohort, 917 were successfully genotyped for >90% of SNPs and passed quality metrics. After adjusting for covariates, 26 SNPs with p < 0.01 for one or more outcomes were selected for replication cohort validation, which included 362 infants (170 cases and 192 controls). A variant in SERPINE1, which encodes plasminogen activator inhibitor (PAI1), was associated with the combined outcome of CP or death in the discovery analysis (p = 4.1 × 10-4) and was significantly associated with CP or death in the replication cohort (adjusted odd ratio: 0.4; 95% confidence interval: 0.2-1.0; p = 0.039). CONCLUSION: A genetic variant in SERPINE1, involved in inflammation and coagulation, is associated with CP or death among ELBW infants. KEY POINTS: · Early preterm and ELBW infants have dramatically increased risks of CP and developmental delay.. · A genetic variant in SERPINE1 is associated with CP or death among ELBW infants.. · The SERPINE1 gene encodes the serine protease inhibitor plasminogen activator inhibitor..

Prediction of Cerebral Palsy or Death among Preterm Infants Who Survive the Neonatal Period.

OBJECTIVE: To assess whether neonatal morbidities evident by the time of hospital discharge are associated with subsequent cerebral palsy (CP) or death. STUDY DESIGN: This is a secondary analysis of data from a multicenter placebo-controlled trial of magnesium sulfate for the prevention of CP. The association between prespecified intermediate neonatal outcomes (n = 11) and demographic and clinical factors (n = 10) evident by the time of discharge among surviving infants (n = 1889) and the primary outcome of death or moderate/severe CP at age 2 (n = 73) was estimated, and a prediction model was created. RESULTS: Gestational age in weeks at delivery (odds ratio [OR]: 0.74, 95% confidence interval [CI]: 0.67-0.83), grade III or IV intraventricular hemorrhage (IVH) (OR: 5.3, CI: 2.1-13.1), periventricular leukomalacia (PVL) (OR: 46.4, CI: 20.6-104.6), and male gender (OR: 2.5, CI: 1.4-4.5) were associated with death or moderate/severe CP by age 2. Outcomes not significantly associated with the primary outcome included respiratory distress syndrome, bronchopulmonary dysplasia, seizure, necrotizing enterocolitis, neonatal hypotension, 5-minute Apgar score, sepsis, and retinopathy of prematurity. Using all patients, the receiver operating characteristic curve for the final prediction model had an area under the curve of 0.84 (CI: 0.78-0.89). Using these data, the risk of death or developing CP by age 2 can be calculated for individual surviving infants. CONCLUSION: IVH and PVL were the only neonatal complications evident at discharge that contributed to an individual infant's risk of the long-term outcomes of death or CP by age 2. A model that includes these morbidities, gestational age at delivery, and gender is predictive of subsequent neurologic sequelae. KEY POINTS: · Factors known at hospital discharge are identified which are independently associated with death or CP by age 2.. · A model was created and validated using these findings to counsel parents.. · The risk of death or CP can be calculated at the time of hospital discharge..

Sex-Specific Genetic Susceptibility to Adverse Neurodevelopmental Outcome in Offspring of Pregnancies at Risk of Early Preterm Delivery.

OBJECTIVE: To evaluate sex-specific genetic susceptibility to adverse neurodevelopmental outcome (ANO, defined as cerebral palsy [CP], mental, or psychomotor delay) at risk for early preterm birth (EPTB, < 32 weeks). STUDY DESIGN: Secondary case-control analysis of a trial of magnesium sulfate (MgSO4) before anticipated EPTB for CP prevention. Cases are infants who died by the age of 1 year or developed ANO. Controls, matched by maternal race and infant sex, were neurodevelopmentally normal survivors. Neonatal DNA was evaluated for 80 polymorphisms in inflammation, coagulation, vasoregulation, excitotoxicity, and oxidative stress pathways using Taqman assays. The primary outcome for this analysis was sex-specific ANO susceptibility. Conditional logistic regression estimated each polymorphism's odds ratio (OR) by sex stratum, adjusting for gestational age, maternal education, and MgSO4-corticosteroid exposures. Holm-Bonferroni corrections, adjusting for multiple comparisons (p < 7.3 × 10-4), accounted for linkage disequilibrium between markers. RESULTS: Analysis included 211 cases (134 males; 77 females) and 213 controls (130 males; 83 females). An interleukin-6 (IL6) polymorphism (rs2069840) was associated with ANO in females (OR: 2.6, 95% confidence interval [CI]: 1.5-4.7; p = 0.001), but not in males (OR: 0.8, 95% CI: 0.5-1.2; p = 0.33). The sex-specific effect difference was significant (p = 7.0 × 10-4) and was unaffected by MgSO4 exposure. No other gene-sex associations were significant. CONCLUSION: An IL6 gene locus may confer susceptibility to ANO in females, but not males, after EPTB.

The Endosomal Recycling Pathway-At the Crossroads of the Cell.

The endosomal recycling pathway lies at the heart of the membrane trafficking machinery in the cell. It plays a central role in determining the composition of the plasma membrane and is thus critical for normal cellular homeostasis. However, defective endosomal recycling has been linked to a wide range of diseases, including cancer and some of the most common neurological disorders. It is also frequently subverted by many diverse human pathogens in order to successfully infect cells. Despite its importance, endosomal recycling remains relatively understudied in comparison to the endocytic and secretory transport pathways. A greater understanding of the molecular mechanisms that support transport through the endosomal recycling pathway will provide deeper insights into the pathophysiology of disease and will likely identify new approaches for their detection and treatment. This review will provide an overview of the normal physiological role of the endosomal recycling pathway, describe the consequences when it malfunctions, and discuss potential strategies for modulating its activity.

Genetic Variation, Magnesium Sulfate Exposure, and Adverse Neurodevelopmental Outcomes Following Preterm Birth.

OBJECTIVE: To evaluate the association of magnesium sulfate (MgSO4) exposure and candidate gene polymorphisms with adverse neurodevelopmental outcomes following preterm birth. STUDY DESIGN: We performed a nested case-control analysis of a randomized trial of maternal MgSO4 before anticipated preterm birth for the prevention of cerebral palsy (CP). Cases were children who died within 1 year of life or were survivors with abnormal neurodevelopment at age 2 years. Controls were race- and sex-matched survivors with normal neurodevelopment. We analyzed 45 candidate gene polymorphisms in inflammation, coagulation, and vascular regulation pathways and their association with (1) psychomotor delay, (2) mental delay, (3) CP, and (4) combined outcome of death/CP. Logistic regression analyses, conditional on maternal race and child sex, and adjusted for treatment group, gestational age at birth and maternal education, were performed. RESULTS: Four hundred and six subjects, 211 cases and 195 controls, were analyzed. The strongest association was for IL6R (rs 4601580) in which each additional copy of the minor allele was associated with an increased risk of psychomotor delay (adjusted odds ratio 3.3; 95% confidence interval, 1.7-6.5; p < 0.001). CONCLUSION: Candidate gene polymorphisms are associated with death and adverse neurodevelopmental outcomes following preterm birth. MgSO4 may abrogate this genotype association for some loci.

Antenatal Magnesium and Cerebral Palsy in Preterm Infants.

OBJECTIVE: To evaluate the relationship of maternal antenatal magnesium sulfate (MgSO4) with neonatal cranial ultrasound abnormalities and cerebral palsy (CP). STUDY DESIGN: In a randomized trial of MgSO4 or placebo in women at high risk of preterm delivery, up to 3 cranial ultrasounds were obtained in the neonatal period. Images were reviewed by at least 2 pediatric radiologists masked to treatment and other clinical conditions. Diagnoses were predefined for intraventricular hemorrhage, periventricular leukomalacia, intracerebral echolucency or echodensity, and ventriculomegaly. CP was diagnosed at 2 years of age by standardized neurologic examination. RESULTS: Intraventricular hemorrhage, periventricular leukomalacia, intracerebral echolucency or echodensity, and ventriculomegaly were all strongly associated with an increased risk of CP. MgSO4 administration did not affect the risk of cranial ultrasound abnormality observed at 35 weeks postmenstrual age or later. However, for the 82% of infants born at <32 weeks gestation, MgSO4 was associated with a reduction in risk of echolucency or echodensity. The reduction in risk for echolucency explained 21% of the effect of MgSO4 on CP (P = .04), and for echodensity explained 20% of the effect (P = .02). CONCLUSIONS: MgSO4 given prior to preterm delivery was associated with decreased risk of developing echodensities and echolucencies at <32 weeks gestation. However, this effect can only partially explain the effect of MgSO4 on CP at 2 years of age. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00014989.

Identifying post-menopausal women at elevated risk for epithelial ovarian cancer.

OBJECTIVE: We developed and validated a hybrid risk classifier combining serum markers and epidemiologic risk factors to identify post-menopausal women at elevated risk for invasive fallopian tube, primary peritoneal, and ovarian epithelial carcinoma. METHODS: To select epidemiologic risk factors for use in the classifier, Cox proportional hazards analyses were conducted using 74,786 Women's Health Initiative (WHI) Observational Study (OS) participants. To construct a combination classifier, 210 WHI OS cases and 536 matched controls with serum marker measurements were analyzed; validation employed 143 cases and 725 matched controls from the WHI Clinical Trial (CT) with similar data. RESULTS: Analyses identified a combination risk classifier composed of two elevated-risk groups: 1) women with CA125 or HE4 exceeding a 98% specificity threshold; and 2) women with intact fallopian tubes, prior use of menopausal hormone therapy for at least two years, and either a first degree relative with breast or ovarian cancer or a personal history of breast cancer. In the WHI OS population, it classified 13% of women as elevated risk, identifying 30% of ovarian cancers diagnosed up to 7.8years post-enrollment (Hazard Ratio [HR]=2.6, p<0.001). In the WHI CT validation population, it classified 8% of women as elevated risk, identifying 31% of cancers diagnosed within 7years of enrollment (HR=4.6, p<0.001). CONCLUSION: CA125 and HE4 contributed significantly to a risk prediction classifier combining serum markers with epidemiologic risk factors. The hybrid risk classifier may be useful to identify post-menopausal women who would benefit from timely surgical intervention to prevent epithelial ovarian cancer.

Length of latency with preterm premature rupture of membranes before 32 weeks' gestation.

OBJECTIVE: The objective of the article is to describe latency for patients with preterm premature membrane rupture (PPROM) between 24(0/7) and 31(6/7) weeks' gestation. STUDY DESIGN: Secondary analysis of data collected prospectively in a multicenter clinical trial of magnesium sulfate for cerebral palsy prevention. Women with PPROM and fewer than six contractions per hour at enrollment who were candidates for expectant management (n = 1,377) were included in this analysis. Length of latency was calculated in days by subtracting the time of delivery from the time of membrane rupture. RESULTS: At each week of gestation, median latency between 24 and 28 weeks was similar at approximately 9 days, but it was significantly shorter with PPROM at 29, 30, and 31 weeks (p < 0.001). In addition, the percentage of patients remaining undelivered at 7 days and 14 days was similar for PPROM between 24 and 28 weeks, but it decreased significantly after that. For each gestational age, the proportion of patients remaining pregnant declined in a fashion similar to an exponential pattern. CONCLUSION: Median latency after PPROM is similar from 24 to 28 weeks' gestation, but it shortens with PPROM at and after 29 weeks.

Effect of magnesium sulfate administration for neuroprotection on latency in women with preterm premature rupture of membranes.

OBJECTIVE: This study aims to evaluate whether magnesium sulfate administration for neuroprotection prolongs latency in women with preterm premature rupture of membranes (PPROM) between 24 and 31(6/7) weeks' gestation. STUDY DESIGN: This is a secondary analysis of a randomized controlled trial of magnesium sulfate for prevention of cerebral palsy. Gravid women with a singleton pregnancy between 24 and 31(6/7) weeks' gestation with PPROM without evidence of labor were randomized to receive magnesium sulfate, administered intravenously as a 6-g bolus followed by a constant infusion of 2 g per hour up to 12 hours, or placebo. Maternal outcomes for this analysis were delivery in less than 48 hours and in less than 7 days from randomization. Neonatal outcomes included a composite of respiratory distress syndrome, interventricular hemorrhage grades 3 or 4, periventricular leukomalacia, sepsis, necrotizing enterocolitis, retinopathy of prematurity, or death. RESULTS: A total of 1,259 women were included. The rate of delivery < 48 hours was not different in the magnesium sulfate and the placebo groups (22.2 and 20.7%, p = 0.51). Delivery < 7 days was similar between groups (55.4 and 51.4%, p = 0.16). Median latency was also similar between groups (median [interquartile range], 6.0 days [range, 2.4-13.8 days] and 6.6 days [range, 2.4-15.1 days], p = 0.29). Composite neonatal outcomes did not differ between groups. CONCLUSION: Magnesium sulfate administration given for neuroprotection in women with a singleton gestation with PPROM and without labor before 32 weeks does not impact latency.

Relation between birth weight and weight and height at the age of 2 in children born preterm.

OBJECTIVE: The aim of the study was to evaluate associations between fetal growth and weight at 2 years in infants born preterm using a customized approach for birth weight. STUDY DESIGN: This is a secondary analysis of a multicenter trial that included a 2-year follow-up of children born prematurely. Customized birth weight percentiles were calculated using the Gardosi model for a U.S. population, and the relation between customized percentile and weight and height at 2 years (adjusted for gender using z-score) was determined using regression analysis and by comparing z-scores for children with birth weight <10th versus ≥10th percentile. RESULTS: Weight z-score at 2 years was significantly lower in the <10th than in the ≥10th percentile group (median [interquartile range, IQR]: -0.66 [-1.58, -0.01] vs. -0.23 [-1.05, 0.55]; p < 0.001), and remained after adjusting for maternal education (p < 0.001). A similar relationship was noted for height z-score between groups (median [IQR]: -0.56 [-1.29, 0.19] vs. -0.24 [-0.99, 0.37]; p < 0.001). Positive relationships between customized birth weight percentile and weight and height at 2 years were noted (p < 0.001 for both), but were not strong (R (2) = 0.04 and 0.02, respectively). CONCLUSION: Customized birth weight percentile is a minor determinant of weight at 2 years among children born preterm.

The association of cord serum cytokines with neurodevelopmental outcomes.

OBJECTIVE: To test whether elevated umbilical cord serum inflammatory cytokine levels predicted subsequent cerebral palsy (CP) or neurodevelopmental delay (NDD). STUDY DESIGN: Nested case-control analysis within a clinical trial of antenatal magnesium sulfate (MgSO4) before anticipated preterm birth (PTB) for prevention of CP, with evaluation of surviving children at the age of 2. NDD was defined as a Bayley psychomotor developmental index (PDI) and/or mental developmental index (MDI) < 70. Controls, defined as surviving children without CP and with Bayley PDI and MDI ≥ 85, were matched by race and gestational age. Cord serum was analyzed for interleukin-8 (IL-8) interleukin-1 beta (IL-1ß), and tumor necrosis factor-α (TNF-α) levels. Elevated cytokine levels were defined as ≥ 75th percentile in placebo-exposed controls. Analyses compared case/control cytokine levels, adjusting for MgSO4 exposure, gestational age, race/ethnicity, and sociodemographic differences. RESULTS: Logistic regression analysis with 339 cases and 276 controls showed that elevated IL-8 and IL-1ß were more common in cord blood serum from infants with subsequent low MDI as compared with controls. After adjusting for additional confounders, the significant differences were no longer evident. Cytokine levels (IL-8, IL-1ß, and TNF-α) were not elevated with CP or low PDI. CONCLUSION: Cord serum IL-8, IL-1ß, and TNF-α levels in preterm infants are not associated with subsequent CP or NDD.

Association of cord blood digitalis-like factor and necrotizing enterocolitis.

OBJECTIVE: Endogenous digoxin-like factor (EDLF) has been linked to vasoconstriction, altered membrane transport, and apoptosis. Our objective was to determine whether increased EDLF in the cord sera of preterm infants was associated with an increased incidence of necrotizing enterocolitis (NEC). STUDY DESIGN: Cord sera from pregnant women enrolled in a randomized trial of MgSO4 for fetal neuroprotection were analyzed for EDLF using a red cell Rb(+) uptake assay in which the inhibition of sodium pump-mediated Rb(+) transport was used as a functional assay of EDLF. Specimens were assayed blinded to neonatal outcome. Cases (NEC, n = 25) and controls (neonates not developing stage 2 or 3 NEC, n = 24) were matched by study center and gestational age. None of the women had preeclampsia. Cases and controls were compared using the Wilcoxon test for continuous and the Fisher exact test for categorical variables. A conditional logistic regression analysis was used to assess the odds of case vs control by EDLF level. RESULTS: Cases and controls were not significantly different for gestational age, race, maternal steroid use, premature rupture of membranes, or MgSO4 treatment. In logistic models adjusted for treatment group, race, premature rupture of membranes, and gestational age, cord sera EDLF was significantly associated with development of NEC (P = .023). CONCLUSION: These data demonstrated an association between cord sera EDLF and NEC.

Investigating the association of lactation history and postmenopausal breast cancer risk in the Women's Health Initiative.

Prolonged lactation (≥24 mo) has been associated with reduced breast cancer risk. This research examined this association in postmenopausal women in the Women's Health Initiative (WHI) Hormone Trial (HT) and Observational Study (OS). This retrospective cohort analysis included 69,358 predominantly overweight (65.4%), white (83.2%) postmenopausal women without breast cancer. Women in the HT were randomized to 0.625 mg conjugated equine estrogen (CEE), 0.625 CEE + 2.5 mg medroxyprogesterone acetate (CEE/MPA), or placebo. OS participants had no restrictions on hormone use. Lactation history was assessed via WHI Reproductive History Questionnaire. Most women breastfed at least 1 mo (58.0%); 35.4% breastfed 1-2 children; and 6.5% stated having breastfed ≥24mo. Women in the HT-CEE who breastfed their first child between 20-24 yr of age demonstrated a nonsignificant decreased risk of breast cancer (HR: 0.62; 95% CI: 0.38, 1.01). OS participants who reported CEE/MPA hormone use and age of first breastfeeding ≥30 yr showed a significant increased risk of breast cancer (HR: 1.66; 95% CI: 1.14, 2.41). Risk was increased if age of last breastfeeding was ≥35yr (HR: 1.50; 95% CI: 1.05, 2.14). This research did not demonstrate a significantly decreased risk of postmenopausal breast cancer in women who breastfed for ≥24 mo during their lifetime.

The association of cerebral palsy and death with small-for-gestational-age birthweight in preterm neonates by individualized and population-based percentiles.

OBJECTIVE: The objective of the study was to determine whether an individualized growth standard (IS) improves the identification of preterm small-for-gestational-age (SGA) neonates at risk of developing moderate/severe cerebral palsy (CP) or death. STUDY DESIGN: This study was a secondary analysis of data from a randomized trial of MgSO4 for the prevention of CP or death among anticipated preterm births. Singleton nonanomalous liveborns delivered before 34 weeks' were classified as SGA (less than the 10th percentile for their gestational age) by a population standard (PS) or an IS (incorporating maternal age, height, weight, parity, race/ethnicity, and neonatal sex). The primary outcome was the prediction of moderate or severe CP or death by age 2 years. RESULTS: Of 1588 eligible newborns, 143 (9.4%) experienced CP (n = 33) or death (n = 110). Forty-four (2.8%) were SGA by the PS and 364 (22.9%) by the IS. All PS-SGA newborns also were identified as IS-SGA. SGA newborns by either standard had a similarly increased risk of CP or death (PS: relative risk [RR], 2.4, 95% confidence interval [CI], 1.3-4.3 vs IS: RR, 1.8, 95% CI, 1.3-2.5, respectively). The similarity of RRs remained after stratification by the MgSO4 treatment group. The IS was more sensitive (36% vs 6%, P < .001) but less specific (78% vs 98%, P < .001) for CP or death. The receiver operating characteristic curve analysis revealed a statistically lower area under the curve for the PS, although the ability of either method to predict which neonates would subsequently develop CP or death was poor (PS: 0.55, 95% CI, 0.49-0.60 vs IS: 0.59, 95% CI, 0.54-0.64, P < .001). CONCLUSION: An individualized SGA growth standard does not improve the association with, or prediction of, CP or death by age 2 years.

Cost-effectiveness of trial of labor after previous cesarean in a minimally biased cohort.

OBJECTIVE: To estimate the cost-effectiveness of a trial of labor after one previous cesarean delivery (TOLAC). STUDY DESIGN: A model comparing TOLAC with elective repeat cesarean delivery (ERCD) was developed for a hypothetical cohort with no contraindication to a TOLAC. Probabilistic estimates were obtained from women matched on their baseline characteristics using propensity scores. Cost data, quality-adjusted life-years (QALYs), and data on cerebral palsy were incorporated from the literature. RESULTS: The TOLAC strategy dominated the ERCD strategy at baseline, with $138.6 million saved and 1703 QALYs gained per 100,000 women. The model was sensitive to five variables: the probability of uterine rupture, the probability of successful TOLAC, the QALY of failed TOLAC, the cost of ERCD, and the cost of successful TOLAC without complications. When the probability of TOLAC success was at the base value, 68.5%, TOLAC was preferred if the probability of uterine rupture was 4.2% or less. When the probability of uterine rupture was at the base value, 0.8%, the TOLAC strategy was preferred as long as the probability of success was 42.6% or more. CONCLUSION: A TOLAC is less expensive and more effective than an ERCD in a group of women with balanced baseline characteristics.

The impact of tobacco use on preterm premature rupture of the membranes.

OBJECTIVE: To determine if tobacco use increases the incidence of preterm premature rupture of the membranes (pPROM) or alters perinatal outcomes after pPROM. STUDY DESIGN: This is a secondary analysis of the databases of three completed Eunice Kennedy Shriver National Institute of Child Health and Human Development-supported Maternal Fetal Medicine Units Network studies. Self-reported tobacco exposure data was obtained. Its relationship with the incidence of pPROM and associated neonatal outcome measures were assessed. RESULTS: There was no difference in the incidence of pPROM when comparing nonsmokers to those using tobacco. Although a trend was seen between the incidence of pPROM and the amount smoked, this did not reach statistical significance. Among the patients with pPROM, the use of tobacco was not associated with an increase in perinatal morbidity. CONCLUSION: Our data do not support a significant relationship between tobacco use and pPROM.

Timing of elective repeat cesarean delivery at term and neonatal outcomes.

BACKGROUND: Because of increased rates of respiratory complications, elective cesarean delivery is discouraged before 39 weeks of gestation unless there is evidence of fetal lung maturity. We assessed associations between elective cesarean delivery at term (37 weeks of gestation or longer) but before 39 weeks of gestation and neonatal outcomes. METHODS: We studied a cohort of consecutive patients undergoing repeat cesarean sections performed at 19 centers of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network from 1999 through 2002. Women with viable singleton pregnancies delivered electively (i.e., before the onset of labor and without any recognized indications for delivery before 39 weeks of gestation) were included. The primary outcome was the composite of neonatal death and any of several adverse events, including respiratory complications, treated hypoglycemia, newborn sepsis, and admission to the neonatal intensive care unit (ICU). RESULTS: Of 24,077 repeat cesarean deliveries at term, 13,258 were performed electively; of these, 35.8% were performed before 39 completed weeks of gestation (6.3% at 37 weeks and 29.5% at 38 weeks) and 49.1% at 39 weeks of gestation. One neonatal death occurred. As compared with births at 39 weeks, births at 37 weeks and at 38 weeks were associated with an increased risk of the primary outcome (adjusted odds ratio for births at 37 weeks, 2.1; 95% confidence interval [CI], 1.7 to 2.5; adjusted odds ratio for births at 38 weeks, 1.5; 95% CI, 1.3 to 1.7; P for trend <0.001). The rates of adverse respiratory outcomes, mechanical ventilation, newborn sepsis, hypoglycemia, admission to the neonatal ICU, and hospitalization for 5 days or more were increased by a factor of 1.8 to 4.2 for births at 37 weeks and 1.3 to 2.1 for births at 38 weeks. CONCLUSIONS: Elective repeat cesarean delivery before 39 weeks of gestation is common and is associated with respiratory and other adverse neonatal outcomes.

Association of cord blood magnesium concentration and neonatal resuscitation.

OBJECTIVE: To assess the relationship between umbilical cord blood magnesium concentration and level of delivery room resuscitation received by neonates. STUDY DESIGN: This was a secondary analysis of a controlled fetal neuroprotection trial that enrolled women at imminent risk for delivery between 24 and 31 weeks' gestation and randomly allocated them to receive either intravenous magnesium sulfate or placebo. The cohort included 1507 infants with data available on total cord blood Mg concentration and delivery room resuscitation. Multivariate logistic regression was used to estimate the association between cord blood Mg concentration and highest level of delivery room resuscitation, using the following hierarchy: none, oxygen only, bag-mask ventilation with oxygen, intubation, and chest compressions. RESULTS: There was no relationship between cord blood Mg and delivery room resuscitation (OR, 0.92 for each 1.0-mEq/L increase in Mg; 95% CI, 0.83-1.03). Maternal general anesthesia was associated with increased neonatal resuscitation (OR, 2.51; 95% CI, 1.72-3.68). Each 1-week increase in gestational age at birth was associated with decreased neonatal resuscitation (OR, 0.63; 95% CI, 0.60-0.66). CONCLUSION: Cord blood Mg concentration does not correlate with the level of delivery room resuscitation of infants exposed to magnesium sulfate for fetal neuroprotection.

Duration of membrane rupture and risk of perinatal transmission of HIV-1 in the era of combination antiretroviral therapy.

OBJECTIVE: The objective of the study was to determine whether the duration of membrane rupture of 4 or more hours is a significant risk factor for perinatal transmission of human immunodeficiency virus (HIV) in the era of combination antiretroviral therapy (ART). STUDY DESIGN: This was a prospective cohort study of 717 HIV-infected pregnant women-infant pairs with a delivery viral load available who received prenatal care and delivered at our institution during the interval 1996-2008. RESULTS: The cohort comprised 707 women receiving ART who delivered during this interval. The perinatal transmission rate was 1% in women with membranes ruptured for less than 4 hours and 1.9% when ruptured for 4 or more hours. For 493 women with a delivery viral load less than 1000 copies/mL receiving combination ART in pregnancy, there were no cases of perinatal transmission identified up to 25 hours of membrane rupture. Logistic regression demonstrated only a viral load above 10,000 copies/mL as an independent risk factor for perinatal transmission. CONCLUSION: Duration of membrane rupture of 4 or more hours is not a risk factor for perinatal transmission of HIV in women with a viral load less than 1000 copies/mL receiving combination ART.

Elective repeat cesarean delivery compared with spontaneous trial of labor after a prior cesarean delivery: a propensity score analysis.

OBJECTIVE: The purpose of this study was to determine outcomes, after the use of propensity score techniques, to create balanced groups according to whether a woman undergoes elective repeat cesarean delivery (ERCD) or trial of labor (TOL). STUDY DESIGN: Women who were eligible for a TOL with 1 previous low transverse incision were categorized according to whether they underwent an ERCD or TOL. A propensity score technique was used to develop ERCD and TOL groups with comparable baseline characteristics. Outcomes were assessed with conditional logistic regression. RESULTS: The rates of endometritis, operative injury, respiratory distress syndrome, and newborn infant infection were lower and the rates of hysterectomy and wound complication were higher in the ERCD group. CONCLUSION: Propensity score techniques can be used to generate comparable ERCD and TOL groups. Some types of maternal morbidity (such as hysterectomy) are higher; other types (such as operative injury) are lower in the ERCD group. Although the absolute risk is low, neonatal morbidity appears to be lower in the ERCD group.