Significance of growth discordance in appropriately grown twins.
OBJECTIVE
We sought to determine the perinatal risks associated with growth discordance in appropriately grown twin gestations.


METHODS
We conducted a retrospective cohort study of all twin gestations excluding those complicated by monoamnionicity, twin-twin transfusion syndrome, structural anomalies, selective reduction, or a birthweight <10th percentile. Growth discordance was defined as ≥20%. Outcomes considered were stillbirth, preterm delivery <34 weeks and <28 weeks, and admission to the neonatal intensive care unit. Analyses were stratified by chorionicity.


RESULTS
Of 895 included dichorionic pregnancies, 63 (7.0%) were discordant. Discordant dichorionic twins were not at increased risk of preterm delivery <34 weeks (34.9% vs 25.6%; relative risk [RR], 1.4; 95% confidence interval [CI], 1.0-1.9), preterm delivery <28 weeks (3.2% vs 2.8%; RR, 1.1; 95% CI, 0.3-4.8), or admission to intensive care (26.9% vs 23.5%; RR, 1.5; 95% CI, 1.0-2.3). We had >90% power to detect a 2.5-fold increase in preterm delivery and admission to the neonatal intensive care unit in dichorionic twins. Of 250 monochorionic pregnancies, 23 (9.2%) were discordant. Monochorionic twin pregnancies were at increased risk of preterm delivery <34 weeks (65.2% vs 26.4%; RR, 2.5; 95% CI, 1.7-3.6), preterm delivery <28 weeks (34.8% vs 4.0%; RR, 8.8; 95% CI, 3.7-20.5), and admission to intensive care (68.2% vs 23.3%; RR, 2.9; 95% CI, 2.0-4.3).


CONCLUSIONS
In appropriately grown twins, growth discordance is a risk factor for adverse perinatal outcomes in monochorionic, but not dichorionic, twins. Discordant monochorionic twins may benefit from increased antenatal surveillance.
Department of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, AL, USA.
Lorie M
LM
Harper
Matthew A
MA
Weis
Anthony O
AO
Odibo
Kimberly A
KA
Roehl
George A
GA
Macones
Alison G
AG
Cahill
D000328:Adult; D015331:Cohort Studies; D005260:Female; D047109:Fetal Development; D006801:Humans; D007231:Infant, Newborn; D015931:Intensive Care, Neonatal / Q000706:statistics & numerical data; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology; D059285:Pregnancy, Twin; D047928:Premature Birth / Q000453:epidemiology / Q000209:etiology; D012189:Retrospective Studies; D012307:Risk Factors; D050497:Stillbirth / Q000453:epidemiology; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic