关键词: 早产儿, 母乳, 宏量营养素, 横断面调查

Abstract: Background: There are few reports on the breast milk composition of mothers of premature infants in China. The composition may be affected by genetics and dietary habits. Objective: To explore the content and changes of macronutrients in breast milk of mothers of premature infants with different gestational weeks and different delivery modes at different stages of lactation. Design: Cross-sectional survey. Methods: Mothers of premature infants admitted to NICU with birth weight ＜2,500 g and gestational age＜37 weeks were included. Mothers were＞18 years of age, had no serious congenital malformations, didn't use immunosuppressants, had no breastfeeding contraindications and voluntarily provided fresh breast milk. The whole milk of bilateral breasts was collected at 4 to 5 am by bilateral electric breast pump to disposable breast milk storage bottle, and transported by cold chain. The process of collecting breast milk from mothers to machine for component analysis was completed within 4 hours. MIRIS HMA breast milk analyzer (MIRIS AB, Sweden) was used, and ultrasonic technology was used for homogenization before detection. The clinical information was obtained from the medical records. According to the gestational age of the included mothers, they were categarized into ＜28 weeks group, ~32 weeks group and ~＜37 weeks group. According to the delivery age of the included mothers, they can be categarized into the puerpera in childbearing age ≤34 years old and elderly puerpera > 35 years old. According to the time of collecting breast milk after delivery, they can be categarized into colostrum 1 ~ 7 days postpartum, transition milk ～14 days postpartum and mature milk ~42 days postpartum. Main outcome measures: Macronutrient content in breast milk of mothers of premature infants at different lactation stages. Results: Among 191 mothers of premature infants who met the inclusion criteria, 79 (41.4%) delivered vaginally, aged from 18 to 44 (31.1±4.5) years, and gestational age at delivery was (29.2±2.2) weeks. Among 191 infants, 102 (53.4%) were males and the average birth weight was (1,286±344) g. A total of 305 samples of breast milk were collected, including 55 colostrums, 72 transition milk and 178 mature milk. In colostrum, transition milk and mature milk, the fat increased and the protein decreased successively, and the difference was statistically significant. The multiple comparison results of colostrum, transition milk and mature milk showed that there was significant difference in carbohydrate and total energy, but there was no significant difference in carbohydrate and total energy between transition milk and mature milk. There was no significant difference in macronutrients and total energy in breast milk of premature mothers at different gestational weeks. At different gestational weeks, the protein content in transition milk at 24-28 weeks was higher than that at ~ 32 weeks and ～＜37 weeks, and the carbohydrate content in transition milk at 24-28 weeks and ~ 32 weeks was higher than that at ～＜37 weeks, and the difference was statistically significant. For different delivery methods, the fat in colostrum in vaginal delivery was lower than that of cesarean section, the protein content in transition milk and mature milk in vaginal delivery was lower than that of cesarean section, and the carbohydrate of mature milk in vaginal delivery was higher than that of cesarean section, and the difference was statistically significant. For different maternal ages, the fat and total energy in mature milk were significantly lower in mothers with childbearing age than in elderly mothers. Conclusion: There were significant differences in the macronutrient elements and total energy in breast milk of premature infants at different stages of lactation. It can be considered to carry out breast milk composition analysis to guide the individualized breast-feeding of premature infants in the future.

Key words: Premature infants, Breast milk, Macronutrients, Cross-sectional survey