Feeding challenges in larger versus smaller preterm discordant twins

This single-center retrospective cohort study aims to compare the risk of necrotizing enterocolitis (NEC) and feed intolerance between the larger and the smaller preterm twin in dichorionic (DC) and monochorionic (MC) twins with birth weight discordance (BWD).

All consecutive live-born twin pairs born in the Nanjing Drum Tower Hospital between 1 January 2023, and 31 July 2025, were reviewed. BWD was defined as more than 20% difference in intertwin birth weight. Neonatal outcomes were compared between the larger and the smaller twin within each twin pair. Data on the start time of enteral feeding, time to attain full enteral feeds (FEF), delayed attainment of FEF, number of fasting episodes, maximum physiological weight loss, time to regain birth weight, the average weight growth velocity, and the frequency of breastfeeding were collected.

We included 30 DC twins and 35 MC twins. The smaller twin had a higher frequency of NEC than the larger twin in both the DC group (23.33% vs. 3.33%, P = 0.031) and the MC group (22.86% vs. 2.86%, P = 0.039). The incidence of respiratory distress syndrome was significantly higher (48.57% vs. 17.14%, P = 0.001) and the incidence of bronchopulmonary dysplasia was significantly lower (0.00% vs. 20.00%, P = 0.016) in the larger twin compared with the smaller twin in the MC group; however, no differences were observed in the DC group. Multivariable logistic regression results showed that gestational age and being small for gestational age (SGA) were significant influencing factors for NEC (P < 0.05). The smaller twin required more time to attain FEF compared with the larger twin in the DC group (1 day vs. 6 days, P = 0.002) and the MC group (5 days vs. 8 days, P = 0.000). The frequency of delays in attaining FEF and fasting in the smaller twin were significantly more than those in the larger twin in both groups (P < 0.05). The log-rank test revealed that the larger twin attained FEF earlier than the smaller twin both in the DC group (P = 0.033) and the MC group (P = 0.048). The results of multivariable logistic regression indicated that, in the two groups, gestational age, being SGA, and the smaller twin were significant influencing factors for delayed attainment of FEF (P < 0.05).

In preterm twins with BWD, the smaller twin has an increased risk of NEC compared with the larger one, which may be attributed to the small twin being SGA. Therefore, the smaller twin needs close observation and monitoring in the early phase after birth because these preterm infants are at increased risk for feeding intolerance.