Detection of intrauterine growth retardation in twins using individualized growth assessment: I. Evaluation of growth outcome at birth.
The growth of 17 sets of twins was evaluated at 2 to 3 week intervals from 15 weeks to delivery by measurement of the head circumference, abdominal circumference, and thigh circumference, and estimation of weight. The birth characteristics of these twins were compared to those predicted by Rossavik growth models, derived from second-trimester ultrasound measurements, using the Growth Potential Realization Index (GPRI) and by comparison to population standards. Newborns were classified as normal or intrauterine growth retarded (IUGR) based on their Neonatal Growth Assessment Score, determined from GPRI values. All normal twins had birth weights that were appropriate-for-gestational-age and had few abnormal birth measurements. The birth weight differences between normal twin fetuses were all < 20%. IUGR twins were both small for gestational age (78%) and appropriate-for-gestational-age (22%), and all had 3 or 4 abnormal GPRI values. In only 40% of the cases was the birth-weight difference between a normal and an IUGR twin > 20%. No single anatomic parameter evaluated at birth adequately separated the normal twins from those with IUGR. These results indicate the need for multiple parameter Individualized Growth Assessment in the detection of IUGR in twins.