OBJECTIVE: Our aim was to evaluate head-to-abdominal circumference asymmetr
y as a marker for adverse outcomes in growth-discordant twins.
STUDY DESIGN: We conducted a retrospective cohort study of asymmetric and s
ymmetric twins with greater than or equal to 25% growth discordance, compar
ing their outcomes with those in concordant symmetric twins. Growth was ter
med asymmetric on the basis of a head circumference/abdominal circumference
ratio at greater than or equal to 95th percentile on ultrasonography perfo
rmed less than or equal to4 weeks before delivery.
RESULTS: We evaluated 572 twin pairs. Asymmetric discordant twins were more
likely than symmetric concordant twins to be delivered at less than or equ
al to 34 weeks' gestation (57% vs 27%), to require intubation (36% vs 7%),
to remain in intensive care >1 week (36% vs 3%), and to have an outcome com
posite that included respiratory morbidity, intraventricular hemorrhage, se
psis, or neonatal death (29% vs 6%), all P < .05. Symmetric discordant and
symmetric concordant twins had similar outcomes.
CONCLUSIONS: Discordant twins with head-to-abdominal circumference asymmetr
y have an increased risk of morbidity. Moreover, in the absence of asymmetr
y, outcomes are comparable among discordant and concordant twins.