Objective:To study the effects of early breastfeeding volume on neonatal necrotizing enterocolitis (NEC) and feeding intolerance in very low birth weight infants.Methods:This study retrospectively analyzed the clinical data of 275 cases of very low birth weight infants (birth weight<1 500 g) born in Shenzhen Maternity & Child Healthcare Hospital from June 2017 to May 2018. Based on whether breastfeeding or not and the ratio of breast milk intake over the total volume of intake within two weeks after birth, they were divided into three groups: breast milk intake>50% group (>50% group, n=199), breast milk intake≤50% group (≤50% group, n=55) and formula group ( n=21). Differences in the incidence of NEC and feeding intolerance among the three groups were analyzed using Chi-square test (or Fisher's exact test). Effects of breast milk intake on the incidence of NEC and feeding intolerance were evaluated using univariate and multivariate logistic regression analysis. Results:The incidence of NEC in the >50% group, ≤50% group and formula group was 1.5% (3/199), 27.3% (15/55) and 9.5% (2/21), respectively ( P<0.01), and the incidence of feeding intolerance was 17.6% (35/199), 56.4% (31/55) and 28.6% (6/21), respectively ( χ2=34.826, P<0.01). Univariate logistic regression analysis showed that compared with the >50% group, the risk of NEC in the≤50% and formula group increased ( OR=24.500, 95% CI: 6.755-85.594; OR=6.877, 95% CI: 1.081-43.744); that of feeding intolerance increased in the≤50% group ( OR=6.316, 95% CI: 3.293-12.113). Multivariate logistic regression analysis showed that compared with the >50% group, the risk of NEC in the≤50% and formula groups increased ( OR=28.452, 95% CI: 7.280-111.195; OR=8.610, 95% CI: 1.262-58.766); that of feeding intolerance increased in the≤50% group ( OR=7.207, 95% CI: 3.601-14.425). Conclusions:Breastfeeding accounting for more than half of the total volume of intake within two weeks after birth may reduce the incidence of feeding intolerance and NEC in very low birth weight infants.