Our results confirm that weekly maternal weight gain according to the IOM guidelines results in improved outcomes in twin pregnancies. Importantly, women with a normal or overweight pre-pregnancy BMI whose weekly weight gain was less than recommended, had increased risks of prematurity and lower birth weight infants. Similarly, women with a normal pre-pregnancy BMI whose weekly weight gain was excess than recommended had increased risks of prematurity and lower birth weight infants.

In our population, nuchal translucency, crown-rump length, and combined discordances in monochorionic diamniotic twin pregnancies were not predictive of adverse composite obstetric and neonatal outcomes.

Placenta membranacea is a rare placental disorder characterized by the presence of fetal membranes (complete or partially) covered by chorionic villi. A 35-year-old woman, gravida 1, was admitted for preterm labor at 24 weeks and 5 days. She subsequently developed heavy vaginal bleeding and underwent a classical cesarean delivery for suspected abruption. Postpartum inspection of the placenta demonstrated a small placenta with tan colored membranes, and diffusely scattered placental cotyledons. Histologic examination revealed chorionic villi directly attached to the fetal membranes on the periphery,consistent with the diagnosis of a partial placenta membranacea. Placenta membranacea should be considered in the etiology of painless vaginal bleeding in the second and third trimester. This condition can be associated with other placental abnormalities, such as placenta previa or accreta. Perinatal outcome may include stillbirth, preterm delivery, or neonatal death.

The fetal renal anteroposterior diameter on second- and third-trimester sonography is predictive of an increased risk for neonatal urologic surgery. Surgical risk is best predicted by a third-trimester renal anteroposterior diameter threshold of 15 mm.

Abbreviations AUC, area under the curve; CI, confidence interval; IUFD, intrauterine fetal death; TTTS, twin-twin transfusion syndromeObjectives-To determine whether intertwin discordant abdominal circumference, femur length, head circumference, and estimated fetal weight sonographic measurements in early second-trimester monochorionic diamniotic twins predict adverse obstetric and neonatal outcomes.Methods-We conducted a multicenter retrospective cohort study involving 9 regional perinatal centers in the United States. We examined the records of all monochorionic diamniotic twin pregnancies with two live fetuses at the 16-to 18-week sonographic examination who had serial follow-up sonography until delivery. The intertwin discordance in abdominal circumference, femur length, head circumference, and estimated fetal weight was calculated as the difference between the two fetuses, expressed as a percentage of the larger using the 16-to 18-week sonographic measurements. An adverse composite obstetric outcome was defined as the occurrence of 1 or more of the following in either fetus: intrauterine growth restriction, twin-twin transfusion syndrome, intrauterine fetal death, abnormal growth discordance (≥20% difference), and very preterm birth at or before 28 weeks. An adverse composite neonatal outcome was defined as the occurrence of 1 or more of the following: respiratory distress syndrome, any stage of intraventricular hemorrhage, 5-minute Apgar score less than 7, necrotizing enterocolitis, culture-proven earlyonset sepsis, and neonatal death. Receiver operating characteristic and logistic regressionwith-generalized estimating equation analyses were constructed.Results-Among the 177 monochorionic diamniotic twin pregnancies analyzed, intertwin abdominal circumference and estimated fetal weight discordances were only predictive of adverse composite obstetric outcomes (areas under the curve, 79% and 80%, respectively). Receiver operating characteristic curves showed that intertwin discordances in abdominal circumference, femur length, head circumference, and estimated fetal weight were not acceptable predictors of twin-twin transfusion syndrome or adverse neonatal outcomes.Conclusions-In our cohort, only second-trimester abdominal circumference and estimated fetal weight discordances in monochorionic diamniotic twin pregnancies were predictive of adverse composite obstetric outcomes. Twin-twin transfusion syndrome and adverse neonatal outcomes were not predicted by any of the intertwin discordances measured.