Out of 145 neonates assessed for eligibility, 116 were subsequently randomized into distinct intervention arms. The study consisted of three intervention groups: Group 1 received EBM only, Group 2 received EBM fortification with HMF, and Group 3 received EBM fortification with PTF. The analysis was conducted on a subset of participants in each group (Fig. 1).

Consort flow diagram of randomised control trial. DAMA Discharge against medical advice, EBM Expressed breast milk, HMF Human milk fortifier, NEC Necrotizing enterocolitis, PTF Preterm formula feed

All baseline neonatal demographic variables were comparable between the three groups. The mean ± SD birth weight in the EBM group, HMF group and PTF group was 1299±152 g, 1275±144 and 1320±152 g respectively (p = 0.41). The mean (±SD) gestational age in the EBM group, HMF group, PTF group was 30.4±1.31 wk, 29.9±1.34 wk and 29.9±1.28 wk (p = 0.23) respectively (Table 1).

The maternal characteristics were comparable between three groups. Number of primigravida and multigravida were comparable in all the three groups. Maternal preeclampsia was 18%, 20% and 18% in EBM group, HMF group and PTF group respectively which was statistically insignificant. Incidence of prematurity in previous pregnancy was 6% in EBM group and 7% in HMF group (Table 1).

By the 6th wk of life/discharge, the group receiving EBM fortified with HMF showed a significant increase in weight compared to the other groups. At 6 wk, the average weight of the EBM group was 1873 (±256) g, whereas the HMF fortified group and PTM group had an average weight of 2053 (±251) g and 1968±203 g respectively (Table 2). The average length at 6 wk was 43.0±2.0 cm for the EBM group, 44.6 (±1.9) cm for the HMF fortified group, and 43.6±2.0 cm for the PTF group. A significant difference with a p-value of 0.003 was observed among the groups. The head circumference (HC) at 6 wk was notably higher in the HMF group, measuring 32.9±1.4 cm, compared to the EBM group (31.4±1.6 cm) and the PTF group (32.0±1.6 cm). This difference was statistically significant with a p-value <0.05 (Table 2). However, it's worth noting that the HMF fortified group had a higher incidence of feed intolerance at 25.7%, in contrast to 10.5% in the expressed breast-feeding group and 7.7% in the PTF group.

No cases of NEC stage 2a or above were observed in any of the three groups. Both the EBM and HMF groups showed an increased incidence of late-onset sepsis (36.8% and 40% respectively), but the difference was not statistically significant. The incidence of hyperbilirubinemia requiring phototherapy was higher in the group receiving expressed breast feeding fortified with HMF (68.6%) compared to the other two groups, though the difference was not statistically significant. The incidence of osteopenia of prematurity was higher in the EBM and PTF groups, at 13.2% and 10.3% respectively, compared to 2.9% in the HMF fortified group. However, this difference was not statistically significant. Notably, the mean serum calcium levels were higher in the HMF fortified group (10.3±0.56 mg/dl) compared to the other groups, and this difference was statistically significant. The significance of other co-morbidities is detailed in Table 3.

The duration of hospital stay for neonates on exclusive EBM was 38.2±28.4 d (mean ± SD). In comparison, the durations for those on HMF and PTF were 35.8±8.6 and 34.2±12.0 d (mean ± SD), respectively. The difference in the duration of hospital stay among the groups was not statistically significant, as indicated by a p-value of 0.64. However, there were notable differences in the costs associated with each group. Group 2 (EBM+HMF) bore the highest average cost of hospital stay at ₹1,89,771±63,502 per baby. In contrast, Group 3 (EBM+PTF) had the lowest cost at ₹1,39,750±57,112 per baby. When it comes to additional daily hospital costs, Group 1 (EBM) had none. Group 2 (EBM+HMF) had the highest additional daily cost of ₹3,210, while Group 3 (EBM+PTF) had a more moderate additional daily cost of ₹1,216 (Table 4).