ABSTRACT
Much has been written about ultrasound assessment of fetal growth in this volume (see Chapter 60). This chapter addresses the following specific aspects of growth in the twin fetus:
(1) The importance of correlating ultrasound measurements of the head circumference (HC), abdominal circumference (AC) and femur length to those derived from twin rather than singleton pregnancies;
(2) The distinction between estimates of birth weight in twins with dichorionic versus monochorionic placentation;
(3) Use of the best formula for estimating the in utero weight of the twin fetus and subsequently assigning the appropriate weight centile;
(4) The interpretation of antenatal findings in the normal twin relative to the discordant co-twin;
(5) Distinguishing the small-for-gestational-age (SGA) from the intrauterine growthrestricted (IUGR) fetus;
(6) Raising the index of suspicion regarding the possibility of the occurrence of twin-twin transfusion syndrome (TTTS) in any pregnancy with monochorionic placentation.
