Placental lesions associated with abnormal growth in twins

Abnormal growth in one or both twins may contribute to the increased morbid ity and mortality observed in twin gestation. Our objective in this retrosp ective study of all twin pregnancies delivered at our hospital (n = 240) ov er a 2-year period was to study the relationship between placental lesions and abnormal growth. Standardized placental examinations were performed in 192 cases (80%), which constituted the study population. Two growth abnorma lities were studied: discordant growth as defined by > 15% difference in bi rth weight and small-for-gestational-age (SGA) birth as defined by birth we ight less-than the 10th percentile for gestational age. The majority of twi n pregnancies with either discordant growth (41/57 cases) or SGA birth (26/ 35 cases) had dichorionic placentas. in monochorionic placentas studied by injection there was no significant relationship between vascular anastomose s and discordant growth. Placental weight for small discordant and SGA twin s was equivalent or increased relative to infant weight, a pattern not sugg estive of maternal vascular underperfusion. Eight lesions, five considered to represent chronic placental disease and three considered to represent in trauterine adaptation, were studied as possible predictors of abnormal grow th. The overall prevalence of these lesions in twin placentas was less than that seen in singleton births. Concordance between twin placentas for most lesions was higher than would be expected, based on their prevalence in si ngleton placentas. Two lesions were associated with discordant growth in bo th univariate and multivariate analyses: peripheral cord insertion (OR 3.6, 95% CI 1.7-7.6) and avascular villi (AV; OR 3.2, 95% CI 1.0-10.3). Three p lacental lesions were associated with SGA infants at the univariate level: peripheral cord insertion avascular villi, and maternal vascular underperfu sion. Only peripheral cord insertion (OR 9.8, 95% CI 4.1-23.4) and AV (OR 3 .7, CI 1.0-13.7) were significant in the multivariate analysis. The relativ e increase in peripheral cord insertion and AV with abnormal growth was obs erved for both monochorionic and dichorionic placentas. Subgroups of discor dant infants with and without SGA were both associated with peripheral cord insertion while only those with SGA had an increase in AV. Both peripheral cord insertion and AV were increased in the subgroup with SGA but no disco rdancy. In summary, two placental lesions, peripheral cord insertion indica ting a spatially limited intrauterine compartment and AV indicating occlusi on of fetal vessels in the placenta, were associated with abnormal growth i n twins.