(694) Very low birthweight (VLBW) twins: an analysis of survival and major morbidities

Twin pregnancies have a high risk of perinatal morbidity and mortality, largely due to fetal growth abnormalities and premature birth. This study aims to examine survival rate and major morbidities of very low birth weight(VLBW) infants from twin pregnancies compared to singletons.

Study Design:

This retrospective study involved analysis of data from a national database for VLBW infants born in any of the 19 maternity units in the Republic of Ireland, from 2014-2019. It captures all infants born between 401g-1500g and/or with a gestational age between 22+0 and 29+6 weeks. Survival, major morbidities, and other infant outcomes were analysed.  Pearson chi-squared tests studied the difference between VLBW twins and singletons. 

Results:

In total 2327 singletons and 949 VLBW infants from twin pregnancies were included. Overall, VLBW twins had a higher survival compared to singletons(84.5% v 81.2%, p=.025) and more twins survived without morbidities(70.4% v 63.7%, p=.118). Singleton pregnancies reported a higher proportion of congenital anomalies(9.4% v 6.4%, p=.006). A higher uptake of antenatal care (98.1% v 87.9%, p=.199) and administration of antenatal corticosteroids(91.0% and 87.9%, p=.010) were reported in twin pregnancies compared to singletons. Twin pregnancies reported significantly less chorioamnionitis (11.6% v 10.0%, p= < .001), less necrotizing enterocolitis(4.6% versus 7.6%, p=.002),nosocomial infection(9.9% v 15.0%, p= < .001)and respiratory distress syndrome(77.5% v 78.6%, p=.239).

More twins were born in tertiary units(76.5% v 69.5%, p= < .001) and survived between 24-32 gestational weeks at birth compared to singletons. A higher proportion of singletons died in the delivery room(7.1% v 5.9%, p=.218). Twins received less resuscitation but required more nasal CPAP during initial resuscitation compared to singletons(56.6% v 53.5%, p=.102).

Conclusion:

These findings show higher survival and some significantly lower morbidities in twins versus singletons. The lower congenital anomaly rates in twins, higher access to antenatal care and delivery in tertiary units might contribute to these outcomes.