Accuracy of sonographic chorionicity classification in twin gestations.

OBJECTIVES: To evaluate the accuracy of sonographic classification of chorionicity in a large cohort of twins and investigate which factors may be associated with sonographic accuracy. METHODS: We conducted a secondary analysis of a randomized trial of preterm birth prevention in twins. Sonographic classification of chorionicity was compared with pathologic examination of the placenta. Maternal (age, body mass index, diabetes, and hypertension), obstetric (prior cesarean delivery, gestational age at the first sonographic examination, and antepartum bleeding), and sonographic (oligohydramnios, polyhydramnios, and twin-twin transfusion syndrome) factors were assessed for their possible association with accuracy. RESULTS: A total of 545 twin sets in which chorionicity was classified by sonography before 20 weeks' gestation were included; 455 were dichorionic and 90 were monochorionic based on pathologic examination. Sonography misclassified 35 of 545 twin pregnancies (6.4%): 18 of 455 dichorionic twins (4.0%) and 17 of 90 monochorionic twins (19.0%). The sensitivity and specificity of sonographic diagnosis of monochorionicity were 81.1% and 96.0%, respectively. In a multivariable analysis, pregnancies with initial sonographic examinations before 14 weeks' gestation were less likely to have misclassified chorionicity than those with sonographic examinations at 15 to 20 weeks (odds ratio [OR], 0.47; 95% confidence interval [CI], 0.23-0.96). For each week increase in gestational age, the odds of misclassification rose by 10% (OR, 1.10; 95% CI, 1.01-1.2). In the multivariable analysis, maternal age, body mass index, parity, and prior cesarean delivery were not associated with sonographic accuracy. CONCLUSIONS: Sonography before 20 weeks incorrectly classified chorionicity in 6.4% of twin gestations. Those with first sonographic examinations performed at earlier gestational ages had improved chorionicity diagnosis.

Maternal 25-hydroxyvitamin d and preterm birth in twin gestations.

OBJECTIVE: To assess whether there was an independent association between maternal 25-hydroxyvitamin D concentrations at 24-28 weeks of gestation and preterm birth in a multicenter U.S. cohort of twin pregnancies. METHODS: Serum samples from women who participated in a clinical trial of 17 α-hydroxyprogesterone caproate for the prevention of preterm birth in twin gestations (2004-2006) were assayed for 25-hydroxyvitamin D concentrations using liquid chromatography tandem mass spectrometry (n=211). Gestational age was determined early in pregnancy using a rigorous algorithm. Preterm birth was defined as delivery of the first twin or death of either twin at less than 35 weeks of gestation. RESULTS: The mean serum 25-hydroxyvitamin D concentration was 82.7 nmol/L (standard deviation 31.5); 40.3% of women had concentrations less than 75 nmol/L. Preterm birth at less than 35 weeks of gestation occurred in 49.4% of women with 25-hydroxyvitamin D concentrations less than 75 nmol/L compared with 26.2% among those with concentrations of 75 nmol/L or more (P<.001). After adjustment for maternal race and ethnicity, study site, parity, prepregnancy body mass index, season, marital status, education, gestational age at blood sampling, smoking status, and 17 α-hydroxyprogesterone caproate treatment, maternal 25-hydroxyvitamin D concentration of 75 nmol/L or more was associated with a 60% reduction in the odds of preterm birth compared with concentrations less than 75 nmol/L (adjusted odds ratio [OR] 0.4, 95% confidence interval [CI] 0.2-0.8). A similar protective association was observed when studying preterm birth at less than 32 weeks of gestation (OR 0.2, 95% CI 0.1-0.6) and after confounder adjustment. CONCLUSIONS: Late second-trimester maternal 25-hydroxyvitamin D concentrations less than 75 nmol/L are associated with an increase in the risk of preterm birth in this cohort of twin pregnancies. LEVEL OF EVIDENCE: II.

Impact of smoking during pregnancy on functional coagulation testing.

Compounds that are systemically absorbed during the course of cigarette smoking, and their metabolites, affect the coagulation system and cause endothelial dysfunction, dyslipidemia, and platelet activation leading to a prothrombotic state. In addition, smoking increases the activity of fibrinogen, homocysteine, and C-reactive protein. We hypothesize that smoking may affect functional coagulation testing during pregnancy. A secondary analysis of 371 women pregnant with a singleton pregnancy and enrolled in a multicenter, prospective observational study of complications of factor V Leiden mutation subsequently underwent functional coagulation testing for antithrombin III, protein C antigen and activity, and protein S antigen and activity. Smoking was assessed by self-report at time of enrollment (<14 weeks). None of the functional coagulation testing results was altered by maternal smoking during pregnancy. Smoking does not affect the aforementioned functional coagulation testing results during pregnancy.

Second trimester cervical length and risk of preterm birth in women with twin gestations treated with 17-α hydroxyprogesterone caproate.

OBJECTIVE: To compare rates of preterm birth before 35 weeks based on cervical length measurement at 16-20 weeks in women with twin gestations who received 17-α hydroxyprogesterone caproate (17OHPC) or placebo. METHODS: This is a secondary analysis of a randomised, double-blind, placebo-controlled trial of twin gestations exposed to 17OHPC or placebo. Baseline transvaginal ultrasound evaluation of cervical length was performed prior to treatment assignment at 16-20 weeks. Cervical length measurements were categorised according to the 10th, 25th, 50th and 75th percentiles in the women studied. The effect of 17OHPC administration in women with a short (25th percentile) and long (75th percentile) cervix was evaluated. RESULTS: Of 661 twin gestations studied, 221 (33.4%) women enrolled at 11 centers underwent cervical length measurement. The 10th, 25th, 50th, 75th percentiles for cervical length at 16-20 weeks were 32, 36, 40 and 44 mm, respectively. The risk of preterm birth <35 weeks was increased in women with a cervical length <25th percentile (55.8 vs. 36.9%, p=0.02). However, a cervical length >75th percentile at this gestational age interval was not protective for preterm birth (36.5 vs. 42.9%, p=0.42). Administration of 17OHPC did not reduce preterm birth before 35 weeks among those with either a short or a long cervix (64.3 vs. 45.8%, p=0.18 and 38.1 vs. 35.5%, p=0.85, respectively). CONCLUSION: Women with twin gestations and a cervical length below the 25th percentile at 16-20 weeks had higher rates of preterm birth. In this subgroup of women, 17 OHPC did not prevent preterm birth before 35 weeks gestation. A cervical length above the 75th percentile at 16-20 weeks did not significantly reduce the risk of preterm birth in this high risk population.

Neonatal outcomes in twin pregnancies delivered moderately preterm, late preterm, and term.

We compared neonatal outcomes in twin pregnancies following moderately preterm birth (MPTB), late preterm birth (LPTB), and term birth. A secondary analysis of a multicenter, randomized controlled trial of multiple gestations was conducted. MPTB was defined as delivery between 32 (0)/(7) and 33 (6)/(7) weeks and LPTB between 34 (0)/(7) and 36 (6)/(7) weeks. Primary outcome was a neonatal outcome composite consisting of one or more of the following: neonatal death, respiratory distress syndrome, early onset culture-proven sepsis, stage 2 or 3 necrotizing enterocolitis, bronchopulmonary dysplasia, grade 3 or 4 intraventricular hemorrhage, periventricular leukomalacia, pneumonia, or severe retinopathy of prematurity. Among 552 twin pregnancies, the MPTB rate was 14.5%, LPTB 49.8%, and term birth rate 35.7%. The rate of the primary outcome was different between groups: 30.0% for MPTB, 12.8% for LPTB, 0.5% for term birth ( P < 0.001). Compared with term neonates, the primary neonatal outcome composite was increased following MPTB (relative risk [RR] 58.5; 95% confidence interval [CI] 11.3 to 1693.0) and LPTB (RR 24.9; 95% CI 4.8 to 732.2). Twin pregnancies born moderately and late preterm encounter higher rates of neonatal morbidities compared with twins born at term.

Avascular villi, increased syncytial knots, and hypervascular villi are associated with pregnancies complicated by factor V Leiden mutation.

There is controversy about whether pathologic abnormalities are associated with pregnancies complicated by factor V Leiden (FVL) mutation. The purpose of this study was to evaluate 105 placentas delivered to mothers heterozygous for FVL mutation to determine if there are pathologic changes suggestive of hypoxia or thrombosis, which correlate with mutation status. We examined placentas obtained as part of a prospective study of 5188 pregnancies analyzed for the presence of FVL mutation in either the mother or the infant. One hundred five placentas from mothers heterozygous for the mutation were compared with 225 controls matched for maternal age, race, and geographic site. Of the 330 pregnancies, 50 infants were FVL mutation heterozygotes. Maternal FVL heterozygote status was associated with more frequent increased numbers of syncytial knots (13% vs 4%); the difference remained significant after controlling for hypertension, preeclampsia, small-for-gestational-age infants, and delivery prior to 35 weeks of gestation (odds ratio 3.6, 95% confidence interval 1.5-8.7, P  =  0.004). Maternal FVL heterozygotes had more hypervascular villi (10% vs 3%), with significance retained controlling for delivery route (odds ratio 3.4, 95% confidence ratio 1.2-9.4, P  =  0.018). Placentas from infants heterozygous for FVL mutation had more avascular villi than controls (odds ratio 2.9, 95% confidence interval 1.5-5.6, P  =  0.001). Fetal or maternal FVL heterozygosity was not associated with infarcts, small-for-gestational-age placentas, or fetal thrombotic vasculopathy. This analysis demonstrates that pathologic findings associated with placental hypoxia, specifically focal avascular villi, increased numbers of syncytial knots, and hypervascular villi, also correlate with FVL heterozygosity in infants or mothers.

Family history of venous thromboembolism and identifying factor V Leiden carriers during pregnancy.

OBJECTIVE: To estimate whether there is a correlation between family history of venous thromboembolism and factor V Leiden mutation carriage in gravid women without a personal history of venous thromboembolism. METHODS: This is a secondary analysis of a prospective observational study of the frequency of pregnancy-related thromboembolic events among carriers of the factor V Leiden mutation. Family history of venous thromboembolism in either first- or second-degree relatives was self-reported. Sensitivity, specificity, and positive and negative predictive values of family history to predict factor V Leiden mutation carrier status were calculated. RESULTS: Women without a personal venous thromboembolism history and with available DNA were included (n=5,168). One hundred forty women (2.7% [95% confidence interval (CI) 2.3-3.2%]) were factor V Leiden mutation-positive. Four hundred twelve women (8.0% [95% CI 7.3-8.7%]) reported a family history of venous thromboembolism. Women with a positive family history were twofold more likely to be factor V Leiden mutation carriers than those with a negative family history (23 of 412 [5.6%] compared with 117 of 4,756 [2.5%], P<.001). The sensitivity, specificity, and positive predictive value of a family history of a first- or second-degree relative for identifying factor V Leiden carriers were 16.4% (95% CI 10.7-23.6%), 92.3% (95% CI 91.5-93.0%), and 5.6% (95% CI 3.6-8.3%), respectively. CONCLUSION: Although a family history of venous thromboembolism is associated with factor V Leiden mutation in thrombosis-free gravid women, the sensitivity and positive predictive values are too low to recommend screening women for the factor V Leiden mutation based solely on a family history.

The effect of active and passive household cigarette smoke exposure on pregnant women with asthma.

BACKGROUND: The article was designed to estimate the effect of active and passive household cigarette smoke exposure on asthma severity and obstetric and neonatal outcomes in pregnant women with asthma. METHODS: We used a secondary observational analysis of pregnant women with mild and moderate-severe asthma enrolled in a prospective observational cohort study of asthma in pregnancy and a randomized clinical trial (RCT) comparing inhaled beclomethasone and oral theophylline. A baseline questionnaire detailing smoking history and passive household smoke exposure was given to each patient. Smoking status was confirmed in the RCT using cotinine levels. Data on asthma severity and obstetric and neonatal outcomes were collected and analyzed with respect to self-reported tobacco smoke exposure. Kruskal-Wallis and Pearson chi(2) statistics were used to test for significance. RESULTS: A total of 2,210 women were enrolled: 1,812 in the observational study and 398 in the RCT. Four hundred and eight (18%) women reported current active smoking. Of the nonsmokers, 790 (36%) women reported passive household smoke exposure. Active smoking was associated with more total symptomatic days (P < .001) and nights of sleep disturbance (P < .001). Among the newborns of active smokers, there was a greater risk of small for gestational age < 10th percentile (P < .001), and a lower mean birth weight (P < .001). There were no differences in symptom exacerbation or outcome between nonsmokers with and without passive household cigarette smoke exposure. CONCLUSIONS: Among pregnant women with asthma, active but not passive smoking is associated with increased asthma symptoms and fetal growth abnormalities.

The effect of 17-alpha hydroxyprogesterone caproate on the risk of gestational diabetes in singleton or twin pregnancies.

OBJECTIVE: To compare the rates of gestational diabetes among women who received serial doses of 17-alpha hydroxyprogesterone caproate vs placebo. STUDY DESIGN: Secondary analysis of 2 double-blind randomized placebo-controlled trials of 17-alpha hydroxyprogesterone caproate given to women at risk for preterm delivery. The incidence of gestational diabetes was compared between women who received 17-alpha hydroxyprogesterone caproate or placebo. RESULTS: We included 1094 women; 441 had singleton and 653 had twin gestations. Combining the 2 studies, 616 received 17-alpha hydroxyprogesterone caproate and 478 received placebo. Among singleton and twin pregnancies, rates of gestational diabetes were similar in women receiving 17-alpha hydroxyprogesterone caproate vs placebo (5.8% vs 4.7%; P = .64 and 7.4% vs 7.6%; P = .94, respectively). In the multivariable model, progesterone was not associated with gestational diabetes (adjusted odds ratio, 1.04; 95% confidence interval, 0.62-1.73). CONCLUSION: Weekly administration of 17-alpha hydroxyprogesterone caproate is not associated with higher rates of gestational diabetes in either singleton or twin pregnancies.

Prevention of preterm birth in triplets using 17 alpha-hydroxyprogesterone caproate: a randomized controlled trial.

OBJECTIVE: To assess whether 17 alpha-hydroxyprogesterone caproate reduces the rate of preterm birth in women carrying triplets. METHODS: We performed this randomized, double-blinded, placebo-controlled trial in 14 centers. Healthy women with triplets were randomly assigned to weekly intramuscular injections of either 250 mg of 17 alpha-hydroxyprogesterone caproate or matching placebo, starting at 16-20 weeks and ending at delivery or 35 weeks of gestation. The primary study outcome was delivery or fetal loss before 35 weeks. RESULTS: One hundred thirty-four women were assigned, 71 to 17 alpha-hydroxyprogesterone caproate and 63 to placebo; none were lost to follow-up. Baseline demographic data were similar in the two groups. The proportion of women experiencing the primary outcome (a composite of delivery or fetal loss before 35 0/7 weeks) was similar in the two treatment groups: 83% of pregnancies in the 17 alpha-hydroxyprogesterone caproate group and 84% in the placebo group, relative risk 1.0, 95% confidence interval 0.9-1.1. The lack of benefit of 17 alpha-hydroxyprogesterone caproate was evident regardless of the conception method or whether a gestational age cutoff for delivery was set at 32 or 28 weeks. CONCLUSION: Treatment with 17 alpha-hydroxyprogesterone caproate did not reduce the rate of preterm birth in women with triplet gestations. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, www.clinicaltrials.gov, NCT00099164 LEVEL OF EVIDENCE: I.

Sample bias among women with retained DNA samples for future genetic studies.

OBJECTIVE: To evaluate whether women who agree to future use of their biologic specimens for genetic studies reflect the larger study population from which they are derived. METHODS: Women were questioned as to the future disposition of their maternal and fetal DNA samples upon enrollment in a multicenter, observational study originally designed to identify factor V Leiden mutation carriers and prospectively ascertain the estimated rate of pregnancy-related venous thromboembolism and adverse pregnancy outcome. Univariate and multivariate analyses was carried out on the 5,003 of 5,188 enrolled women who indicated their desire regarding future disposition of their DNA samples. RESULTS: Among these 5,003 women, 20.1% desired that their samples be discarded and not available for future genetic studies. Multivariate analysis demonstrated that women who agreed to subsequent use of samples were less likely African-American (odds ratio [OR] 0.6, 95% confidence interval [CI] 0.4-0.7) or Hispanic (OR 0.4, 95% CI 0.3-0.5), and more likely to use tobacco (OR 1.2, 95% CI 1.0-1.6) than those who desired that their samples be discarded. CONCLUSION: Genetic samples from women agreeing to their use in a sample repository may not be representative of the index study cohort. This should be considered in their subsequent interpretation and generalizability. LEVEL OF EVIDENCE: III.

Association of obesity with pulmonary and nonpulmonary complications of pregnancy in asthmatic women.

OBJECTIVE: To evaluate whether maternal obesity is associated with pulmonary and nonpulmonary pregnancy complications in asthmatic women. METHODS: This is a secondary analysis of the prospective cohort Asthma During Pregnancy Study. Asthma patients were classified as having either mild or moderate to severe disease at the beginning of the study. Rates of pulmonary complications of asthma in asthmatic women and rates of nonpulmonary complications of pregnancy among asthma patients and controls, were compared between obese (body mass index > or = 30 kg/m2) and nonobese women. RESULTS: Maternal body mass index and pregnancy outcome data were available for 1,699 of 1,812 asthmatic women and for 867 of 881 controls. Of the asthma subjects, 30.7% (521) were obese compared with 25.5% of the controls, P = .006. Obese women, regardless of whether they had asthma, were more likely to undergo cesarean delivery (OR 1.6, 95% confidence interval [CI]1.3-2.0) to develop preeclampsia or gestational hypertension (OR 1.7 95% CI 1.3-2.3) and gestational diabetes (OR 4.2, 95% CI 2.8-6.3). There were no differences in the rates of overall asthma improvement (20.6% compared with 23.6%, P = .36) or deterioration (33.3% compared with 28.8%, P = .20) between obese and nonobese asthma patients. After adjustment for confounding variables, obesity, not asthma, was associated with nonpulmonary complications of pregnancy, and obesity was associated with an increase in asthma exacerbations as well (OR 1.3, 95% CI 1.1-1.7). CONCLUSION: Obesity is associated with an increased risk of asthma exacerbations during pregnancy. The increased rate of nonpulmonary complications of pregnancy in asthma patients is associated with obesity in this population and not with asthma status. LEVEL OF EVIDENCE: II-1.

Spirometry is related to perinatal outcomes in pregnant women with asthma.

OBJECTIVE: The purpose of this study was to test the hypothesis that maternal asthma symptoms and pulmonary function are related to adverse perinatal outcomes. STUDY DESIGN: Asthmatic patients were recruited from the 16 centers of the Maternal Fetal Medicine Units. Forced expiratory volume in 1 second was obtained at enrollment and at monthly study visits, and the frequency of asthma symptoms was assessed from enrollment to delivery. Perinatal data were obtained at postpartum chart reviews. RESULTS: The final cohort included 2123 participants with asthma. After adjustment for demographic characteristics, smoking, acute asthmatic episodes, and oral corticosteroid use, significant relationships were demonstrated between gestational hypertension and preterm birth and lower maternal gestational forced expiratory volume in 1 second. The data did not show any significant independent relationship between asthma symptom frequency and perinatal outcomes. CONCLUSION: Lower pulmonary function during pregnancy is associated with increased gestational hypertension and prematurity in the pregnancies of women with asthma, which may be due to inadequate asthma control or factors that are associated with increased asthma severity.

The relationship of asthma medication use to perinatal outcomes.

BACKGROUND: Maternal asthma has been reported to increase the risk of preeclampsia, preterm deliveries, and lower-birth-weight infants, but the mechanisms of this effect are not defined. OBJECTIVE: We sought to evaluate the relationship between the use of contemporary asthma medications and adverse perinatal outcomes. METHODS: Asthmatic patients were recruited from the 16 centers of the National Institute of Child Health and Human Development Maternal Fetal Medicine Units Network from December 1994 through February 2000. Gestational medication use was determined on the basis of patient history at enrollment and at monthly visits during pregnancy. Perinatal data were obtained at postpartum chart reviews. Perinatal outcome variables included gestational hypertension, preterm births, low-birth-weight infants, small-for-gestational-age infants, and major malformations. RESULTS: The final cohort included 2123 asthmatic participants. No significant relationships were found between the use of inhaled beta-agonists (n=1828), inhaled corticosteroids (n=722), or theophylline (n=273) and adverse perinatal outcomes. After adjusting for demographic and asthma severity covariates, oral corticosteroid use was significantly associated with both preterm birth at less than 37 weeks' gestation (odds ratio, 1.54; 95% CI, 1.02-2.33) and low birth weight of less than 2500 g (odds ratio, 1.80; 95% CI, 1.13-2.88). CONCLUSIONS: Use of inhaled beta-agonists, inhaled steroids, and theophylline do not appear to increase perinatal risks in pregnant asthmatic women. The mechanism of the association between maternal oral corticosteroid use and prematurity remains to be determined.

Asthma during pregnancy.

OBJECTIVE: To determine neonatal and maternal outcomes stratified by asthma severity during pregnancy by using the 1993 National Asthma Education Program Working Group on Asthma and Pregnancy definitions of asthma severity. The primary hypothesis was that moderate or severe asthmatics would have an increased incidence of delivery at <32 weeks of gestation compared with nonasthmatic controls. METHODS: This was a multicenter, prospective, observational cohort study conducted over 4 years at 16 university hospital centers. Asthma severity was defined according to the National Asthma Education Program Working Group on Asthma and Pregnancy classification and modified to include medication requirements. This study had 80% power to detect a 2- to 3-fold increase in delivery less than 32 weeks of gestation among the cohort with the moderate or severe asthma compared with controls. Secondary outcome measures included obstetrical and neonatal outcomes. RESULTS: The final analysis included 881 nonasthmatic controls, 873 with mild asthma, 814 with moderate, and 52 with severe asthma. There were no significant differences in the rates of preterm delivery less than 32 weeks (moderate or severe 3.0%, mild 3.4%, controls 3.3%; P =.873) or less than 37 weeks of gestation. There were no significant differences for neonatal outcomes except discharge diagnosis of neonatal sepsis among the mild group compared with controls, adjusted odds ratio 2.9, 95% confidence interval 1.2, 6.8. There were no significant differences for maternal complications except for an increase in overall cesarean delivery rate among the moderate-or-severe group compared with controls (adjusted odds ratio 1.4, 95% confidence interval 1.1, 1.8). CONCLUSION: Asthma was not associated with a significant increase in preterm delivery or other adverse perinatal outcomes other than a discharge diagnosis of neonatal sepsis. Cesarean delivery rate was increased among the cohort with moderate or severe asthma. LEVEL OF EVIDENCE: II-2

Risk factors and outcome of varicella-zoster virus pneumonia in pregnant women.

To determine the factors associated with an increased risk of developing varicella-zoster virus (VZV) pneumonia during pregnancy, a case-control analysis was done in which 18 pregnant women with VZV pneumonia were compared with 72 matched control subjects. VZV infection was identified clinically, and VZV pneumonia was diagnosed by dyspnea and findings on chest radiographs. Of 347 pregnant women with VZV infection, 18 (5.2%) had pneumonia treated with acyclovir, and none died. Mean gestational age at rash onset was 25.8 plus minus 8.8 weeks for patients with pneumonia and 17.7 +/- 10.3 weeks for control subjects, which was not significant in the multivariable model. Women with VZV pneumonia were significantly more likely to be current smokers (odds ratio [OR], 5.1; 95% confidence interval [CI], 1.6-16.7) and to have > or = 100 skin lesions (OR, 15.9; 95% CI, 1.9-130.2). Pregnant women with VZV infection may be more likely to develop varicella pneumonia if they are smokers or manifest > or = 100 skin lesions.