Birthweight is an independent predictor of birth asphyxia in twins: A retrospective cross-sectional cohort study of 5337 Chinese twins.

OBJECTIVE

Few studies are available on birth asphyxia risks in twin neonates. This retrospective multi-center cross-sectional study determined the birthweight percentiles of 5337twins and birth asphyxia incidence of the twin population.

METHODS

We retrieved sociodemographic and obstetric data from the electronic records systems of participating centers. Neonate birthweight was measured within 24 h of birth. Perinatal asphyxia was diagnosed if 5-minute Apgar score was ≤5, or resuscitation was required 10 min after birth. The primary outcome was the incidence of birth asphyxia.

RESULTS

Totally 5337 neonates were eligible. The mean neonatal birthweight was 2227.1 ± 608.99 g and the 5th, 50th, and 95th percentiles of birthweight were 970, 2400, and 3080 g, respectively. The mean Apgar score was 9.06 ± 1.73 at 1 min and 8.99 ± 1.74 at 5 min. Totally 13.5 % (705/5222) twins had asphyxia and 9.35 % and 4.16 % twins had moderate and severe asphyxia, respectively. Twins with a birthweight< 1500 g had the highest asphyxia rate (64.8 %) and twins with a birthweight between 2500 and 3000 g had the lowest asphyxia rate (3.6 %). Stepwise logistic regression analysis revealed that higher birthweight was associated with a significantly reduced risk of asphyxia [OR 0.772 (95 %CI 0.755, 0.789), P < 0.001]. The AUROC for mean twin birthweight was 0.86±0.01 (95 %CI 0.84, 0.88) using a cutoff of 1950 g, with a sensitivity of 0.84 and a specificity of 0.78.

CONCLUSION

Twins have lower birthweight versus singletons and a significant proportion of twins, especially twins with lower birthweight, are at risk of birth asphyxia. Birthweight is an independent predictor of asphyxia and should be further explored as a predictive marker for stratifying asphyxia risks in twin neonates.