ABSTRACT
Abnormal patterns of fetal growth are one of the most common complications of multiple pregnancies. It is believed that twins grow at the same rate as singletons until the 28th week of gestation, followed by a somewhat lower third-trimester rate (see Chapter 60 for details). The etiology of discordant fetal growth or growth restriction in multiple pregnancy is the same as that in singletons: placental insufficiency, early pregnancy infection and chromosomal, structural or constitutional anomalies1,2. A weight discordance in the absence of other pathological problems suggests either that one fetus is suffering from intrauterine growth restriction (IUGR) or has a chromosomal anomaly in the presence of a normal co-twin, or that both fetuses are normal in spite of the discordance, which merely reflects differences in their respective genetic potentials. It is also possible for both twins to be growth restricted and to exhibit concordant size.
