OBJECTIVE: To evaluate the efficacy and safety of lactase drops in the treatment of lactose intolerance in premature infants

so as to promote the breastfeeding rate of premature infants. METHODS: A multi-center and non-randomized controlled clinical study was conduct

preterm infants with gestational age ≤34 weeks and symptoms of feeding intolerance admitted to neonatology departments of the Children’s Hospital of Fudan University

the Shanghai Children’s Medical Center Affiliated to Shanghai Jiaotong University and the Children’s Hospital of Shanghai were selected as research objects

which were divided into research group and control group via non-randomized method. The research group was given breast milk + lactase or liquid milk for preterm infants + lactase

while the control group was fed with deeply hydrolyzed lactose-free formula or amino acid formula. The primary observation indicators were lactose intolerance symptoms

stool pH and fecal reducing sugar; the secondary observation indicators were growth and development indicators. RESULTS: A total of 117 premature infants were enrolled from Jul. 2017 to Jul. 2020

finally 56 children in the research group and 18 children in the control group had completed the study. Compared with the control group

the research group had a greater rate of weight gain at 2 weeks of enrollment

with statistically significant difference（P<0.05）. There was no statistical significance in differences in the reduction of stool frequency

results of stool pH test and percentage of negative conversion of fecal reducing sugar between two groups after 2 weeks of enrollment（P>0.05）. CONCLUSIONS: Both lactase and lactose-free formula can effectively treat lactase deficiency. Although the onset of action of lactase is slower than that of lactose-free formula

breast milk combined with lactase feeding can significantly help children’s weight gain without giving up breastfeeding.