Faculty Bibliography

OBJECTIVE: To compare maternal and neonatal outcomes in obese vs. non-obese women with gestational diabetes (GDM) treated with diet only, oral Glyburide or insulin. STUDY DESIGN: Women with a singleton gestation enrolled for outpatient perinatal services diagnosed with GDM and without history of pregnancy-related hypertension (gestational hypertension or preeclampsia) in a prior pregnancy or diagnosed with pregnancy-related hypertension at enrollment for outpatient services were identified in a database. Included were those women whoseGDMwas controlled by diet only (n=3918); oral glyburide (n=873); or insulin without prior exposure to oral hypoglycemic agents (n=2229).GDMdiagnosis and treatment was determined by each patient's individual physician. Maternal and neonatal outcomes were compared for obese (pre-pregnancy body mass index>30kg/m²) vs. non-obese women within each GDM treatment group and also compared across treatment groups within the obese and non-obese populations. RESULTS: Within each treatment group obesity was associated with higher rates of cesarean delivery, diagnosis of pregnancy-related hypertension, birth weight >4000gms, and hyperbilirubinemia (all p<0.05). Significant maternal and neonatal outcomes across treatment groups are presented in table (adjusted p<0.05 vs. ¹ Diet only, and ² Glyburide groups) CONCLUSIONS: In this large observational study of women with GDM, including 873 women receiving Glyburide, we found significantly higher rates of pregnancy-related hypertension and infant hyperbilirubinemia in pregnancies receiving Glyburide for management of GDM. These findings should be considered when pharmacologic treatment of GDM is necessary. (Table presented)

OBJECTIVE: The purpose of this study was to define normal second-trimester cervical length (CL) measurements and to estimate the association between second-trimester CL and spontaneous preterm birth (SPTB) in twin pregnancies. METHODS: A retrospective cohort of 309 asymptomatic patients with twin pregnancies who had routine outpatient CL assessment in the second trimester was studied. We looked at the gestational age periods of 16 to 17 6/7, 18 to 19 6/7, 20 to 21 6/7, and 22 to 23 6/7 weeks. We estimated the association between the CL measurement during each period and SPTB. A short CL was defined both as a CL at or below the 10th percentile for gestational age and 25 mm or less. We also performed regression analyses controlling for a number of clinically important factors: maternal age, chorionicity, in vitro fertilization, multifetal reduction, prior term births, prior preterm births, prepregnancy body mass index, and cerclage. RESULTS: The CL measurement at 16 to 17 6/7 weeks was not associated with gestational age at delivery or SPTB. At 18 to 19 6/7 and 20 to 21 6/7 weeks, the CL measurement was not significantly associated with gestational age at delivery or SPTB before 28 and 32 weeks. There was an association with SPTB before 35 weeks. At 22 to 23 6/7 weeks, the CL measurement had a significant association with gestational age at delivery and SPTB before 28, 32, and 35 weeks (P < .05). A short CL at 22 to 23 6/7 weeks was significantly associated with SPTB before 32 and 35 weeks (P < .05). CONCLUSIONS: In second-trimester twin pregnancies, the strongest association between CL and SPTB is at 22 to 23 6/7 weeks.

OBJECTIVE: To estimate whether the weight gain recommendations for twin pregnancies in the 2009 Institute of Medicine (IOM) guidelines are associated with improved perinatal outcomes. METHODS: A cohort of 297 twin pregnancies was identified from a single practice with measured prepregnancy body mass index (BMI) and weight gain during pregnancy. Recommended IOM guidelines were applied to our cohort based on prepregnancy BMI categories (normal weight, overweight, obese). Pregnancy outcomes were compared between patients whose weight gain met or exceeded the IOM recommendations and patients who did not meet these recommendations. RESULTS: Patients with normal prepregnancy BMIs whose weight gain met the IOM recommendations had significantly improved outcomes compared with patients who did not meet the IOM recommendations. They were less likely to have preterm birth before 32 weeks (5.0% compared with 13.8%) and spontaneous preterm birth before 32 weeks (3.4% compared with 11.5%). They also delivered significantly larger neontates (larger twin birth weight 2,582.1+/-493.4 g compared with 2,370.3+/-586.0 g; smaller twin birth weight 2,277.0+/-512.1 g compared with 2,109.3+/-560.9 g) and were significantly more likely to have both neonates weigh more than 2,500 g (38.8% compared with 22.5%) and more than 1,000 g (97.5% compared with 91.2%) and were less likely to deliver any twin with a birth weight lower than the fifth percentile for gestational age (21.5% compared with 35.0%). CONCLUSION: In women with twin pregnancies and normal starting BMIs, weight gain during pregnancy is significantly associated with improved outcomes, including a decreased risk of prematurity and larger birth weights. LEVEL OF EVIDENCE: II.

Omega-3 fatty acids are essential fatty acids that must be consumed in the diet. Adequate consumption of omega-3 fatty acids is vitally important during pregnancy as they are critical building blocks of fetal brain and retina. Omega-3 fatty acids may also play a role in determining the length of gestation and in preventing perinatal depression. The most biologically active forms of omega-3 fatty acids are docosahexaenoic acid and eicosapentaenoic acid, which are primarily derived from marine sources such as seafood and algae. Recent surveys, however, indicate that pregnant women in the United States and in other countries eat little fish and therefore do not consume enough omega-3 fatty acids, primarily due to concern about the adverse effects of mercury and other contaminants on the developing fetus. This review discusses the benefits of omega-3 fatty acid consumption during pregnancy and provides guidelines for obstetricians advising patients.

Continuous observations, such as reaction and run times, and binary observations, such as correct/incorrect responses, are recorded routinely in behavioral learning experiments. Although both types of performance measures are often recorded simultaneously, the two have not been used in combination to evaluate learning. We present a state-space model of learning in which the observation process has simultaneously recorded continuous and binary measures of performance. We use these performance measures simultaneously to estimate the model parameters and the unobserved cognitive state process by maximum likelihood using an approximate expectation maximization (EM) algorithm. We introduce the concept of a reaction-time curve and reformulate our previous definitions of the learning curve, the ideal observer curve, the learning trial and between-trial comparisons of performance in terms of the new model. We illustrate the properties of the new model in an analysis of a simulated learning experiment. In the simulated data analysis, simultaneous use of the two measures of performance provided more credible and accurate estimates of the learning than either measure analyzed separately. We also analyze two actual learning experiments in which the performance of rats and of monkeys was tracked across trials by simultaneously recorded reaction and run times and the correct and incorrect responses. In the analysis of the actual experiments, our algorithm gave a straightforward, efficient way to characterize learning by combining continuous and binary measures of performance. This analysis paradigm has implications for characterizing learning and for the more general problem of combining different data types to characterize the properties of a neural system.

OBJECTIVE: The objective of the study was to determine the relationship between fetal fibronectin (fFN) testing prior to ultrasound-indicated cerclage and obstetric outcome. STUDY DESIGN: Singleton pregnancies between 18 and 24 weeks' gestation with an ultrasound-diagnosed short cervix (< 25 mm) and funneling (> 25%) of the chorioamniotic membranes into the endocervical canal were analyzed. The fFN testing was performed and patients were randomized to cerclage or no-cerclage. Groups were stratified by fFN result. Cerclage patients were compared with no-cerclage patients. The primary outcome was delivery prior to 35 weeks' gestation. RESULTS: Spontaneous preterm birth prior to 35 weeks' gestation occurred in 15 (44.1%) fFN-positive-cerclage patients and 16 (55.2%) fFN-positive no-cerclage patients (P = .45). Similarly, it occurred in 16 (17.8%) fFN-negative cerclage patients and 11 (17%) fFN-no-cerclage patients (P = .99). CONCLUSION: fFN did not identify optimal candidates for cerclage. However, fFN testing before an ultrasound-indicated cerclage aids in counseling patients, anticipating the outcome of pregnancies complicated by cervical shortening

Continuous (reaction times) and binary (correct/ incorrect responses) measures of performance are routinely recorded to track the dynamics of a subject's cognitive state during a learning experiment. Current analyses of experimental data from learning studies do not consider the two performance measures together and do not use the concept of the cognitive state formally to design statistical methods. We develop a mixed filter algorithm to estimate the cognitive state modeled as a linear stochastic dynamical system from simultaneously recorded continuous and binary measures of performance. The mixed filter algorithm has the Kalman filter and the more recently developed recursive filtering algorithm for binary processes as special cases. In the analysis of a simulated learning experiment the mixed filter algorithm provided a more accurate and precise estimate of the cognitive state process than either the Kalman or binary filter alone. In the analysis of an actual learning experiment in which a monkey's performance was tracked by its series of reaction times, and correct and incorrect responses, the mixed filter gave a more complete description of the learning process than either the Kalman or binary filter. These results establish the feasibility of estimating cognitive state from simultaneously recorded continuous and binary performance measures and suggest a way to make practical use of concepts from learning theory in the design of statistical methods for the analysis of data from learning experiments.