To evaluate the association between respiratory distress syndrome (RDS) and intrauterine fetal growth restriction (IUGR) by using a dichorionic twin model.

We retrospectively analyzed twins delivered between September 2012 and December 2018. A dichorionic (DC) twin pregnancy with selective IUGR (sIUGR) was defined as the presence of (i) a birthweight discordance of ≥25% and (ii) a smaller twin with birth weight below the 10th percentile. Pregnancies with major fetal anomalies, delivery at gestational age below 23 weeks, and intrauterine fetal demise were excluded.

We included 53 DC twins with sIUGR. The sIUGR twin had a higher risk of RDS than did his appropriate for gestational age (AGA) cotwin (32.1% vs. 11.3%, p = 0.001); however, the risk of severe RDS did not significantly differ between the twins (17.0% vs 9.4%, p = 0.125). The findings of logistic regression analysis indicated that younger gestational age (weeks) at delivery (odds ratio = 0.48, p < 0.001) and IUGR (odds ratio = 13.87, p = 0.009) were significant risk factors for RDS in newborns in DC twin pregnancies with selective sIUGR.

IUGR was identified as a risk factor for newborn RDS. However, the association between IUGR and severe newborn RDS was not significant possibly due to the small sample size of this study.