Diane Timms

Demographic differences in Down syndrome livebirths in the US from 1989 to 2006

To explore demographic differences in Down syndrome livebirths in the United States.

Short-term neonatal outcomes in diamniotic twin pregnancies delivered after 32 weeks and indications of late preterm deliveries.

OBJECTIVE We sought to compare neonatal outcomes in twin pregnancies following moderately preterm birth (MPTB), late preterm birth (LPTB), and term birth and determine the indications of LPTB. STUDY DESIGN We performed a retrospective cohort study. 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. The composite neonatal adverse respiratory outcome was defined as respiratory distress syndrome and/or bronchopulmonary dysplasia. The composite neonatal adverse nonrespiratory outcome included early onset culture-proven sepsis, necrotizing enterocolitis, retinopathy of prematurity, intraventricular hemorrhage, or periventricular leukomalacia. LPTB cases were categorized as spontaneous (noniatrogenic), evidence-based iatrogenic, and non-evidence-based (NEB) iatrogenic. RESULTS Of the 747 twin deliveries during the study period, 453 sets met the inclusion criteria with 22.7% (n = 145) MPTB, 32.1% (n = 206) LPTB, and 15.9% (n = 102) term births. Compared with term neonates, the composite neonatal adverse respiratory outcome was increased following MPTB (relative risk [RR] 24; 95% confidence interval [CI] 3.0 to 193.6) and LPTB (RR 13.7; 95% CI 1.8 to 101.8). Compared with term neonates, the composite neonatal adverse nonrespiratory outcome was increased following MPTB (RR 22.3; 95% CI 3.9 to 127.8) and LPTB (RR 5.5; 95% CI 1.1 to 27.6). Spontaneous delivery of LPTB was 63.6% (n = 131/206) and the rate of iatrogenic delivery was 36.4% (n = 75/206). The majority, 66.6% (n = 50/75), of these iatrogenic deliveries were deemed NEB, giving a total of 24.2% (50/206) NEB deliveries in LPTB group. CONCLUSION Our data demonstrate a high rate of late preterm birth among twin pregnancies, with over half of nonspontaneous early deliveries due to NEB indications. Although our morbidity data will be helpful to providers in counseling patients, our finding of high NEB indications underscores the need for systematic evaluation of indications for delivery in LPTB twin deliveries. Furthermore, this may lead to more effective LPTB rate reduction efforts.

Modifying Risk for Aneuploidy with Second-Trimester Ultrasound After a Positive Serum Screen

Prenatal diagnosis for aneuploidy (primarily Down syndrome) has evolved over the past 4 decades. It started as a screening process using maternal age of 35 years or older as a risk factor to offer patients the option for prenatal diagnosis. The actual diagnosis used an invasive procedure (amniocentesis) to obtain fetal cells for processing to determine fetal karyotype. This had a potential risk for miscarriage. The development of noninvasive prenatal screening to better identify pregnant patients at high risk for Down syndrome improved the ability to detect cases of aneuploidy and limit amniocentesis to only patients considered at high risk. This approach has a higher detection rate and a lower procedure-related rate of fetal loss than use of maternal age of 35 years or older alone. This article presents an overview of how prenatal diagnosis has evolved and then focuses on the current status of using ultrasound to evaluate patients considered to be screen-positive for Down syndrome based on first-trimester screening (10-14 weeks) or second-trimester (15-22 weeks) maternal serum analyte screening.