Human milk is a product of human evolution and is crucial for the early growth and development of infants as well as maternal health. This paper discusses the research and application of human milk science in China, aiming to clarify the research pathways in this field and contribute to the promotion of breastfeeding initiatives and the realization of the Healthy China 2030 goals.

A comprehensive understanding of the nutritional composition and active components of human milk are important for promoting infant health. However, in the design and implementation of scientific research on human milk, the lack of standardized research and implementation methods have led to the collection, storage, and testing processes of human milk samples being largely based on reference literature and practical experience. This has resulted in variability in the representativeness of human milk samples and differences in the comparability of research results between different studies. This article summarizes the principles and guidelines for the " Specification for collection and storage of human milk samples for research", published by the Chinese Nutrition Society on December 30, 2022, and discusses the feasibility and importance of standardized management in the process of scientific research on human milk.

Breast milk, the product of mammalian evolution, provides infants with not only vital nutrients, but also an array of nourishing contents, including bioactive substances, microorganisms, and cells. Being a crucial stage of reproductive health, breastfeeding serves as the primary means of nutrient absorption during early life. However, the scientific evaluation of its health effects remains inaccurate. The study of breast milk has emerged as a new interdisciplinary research hotspot, offering a new paradigm for explorations in life health, disease prevention, clinical treatment, social ethics, and economic advancement. This paper reviewed and discussed the research progress of breast milk science both domestically and internationally and the gap in between, and proposed a promising perspective for future research and development.

This article is a summary of the Second China Breast Milk Science Conference, which was held in Beijing from August 5 to 7, 2022, with the theme of "Data sharing, method sharing and science sharing". The purpose of the conference is to summarize the latest progress in breast milk research, identify the unresolved issues, and jointly discuss the direction of future breast milk research. Firstly, we summarize the contents and purpose of breast milk scientific research and prospect of breast milk science. The second part focuses on the research status of breast milk composition and its health effects, and puts forward the future research direction. The third section focuses on the health effects of breastfeeding and scientific support and key aspects of breastfeeding promotion actions. The fourth part elaborates the specific methods of current scientific research of breast milk and emphasize the importance of method standardization and the idea of future methodological research. The fifth part consists of the strategy of feeding infants with medical conditions and ways to better promote the growth and development of these infants. The last part introduces the innovation, deficiencies, and future research directions of infant formula production technology in China. This conference demonstrate the importance of multidisciplinary communication, discussions and collaborations in clinical medicine, nutrition, perinatal health, food science, and policy-making in the scientific research of breast milk, and provides guidance for future multidisciplinary research on the physiology of lactation, the composition of breast milk, breastfeeding, and infants and young children nutrition.

Objective:To explore the relationship between vegetarian diets and vitamin B 12 levels in Chinese pregnant women. Methods:A cross-sectional survey was used to explore the relationship between vegetarian diets and vitamin B 12 levels in Chinese pregnant women based on data from the Chinese National Nutrition and Health Surveillance (2015-2017). Maternal serum vitamin B 12 concentration was determined by electrochemiluminescence. Background and diet information of all subjects were collected using general and food frequency questionnaires. General Linear Model was used to analyze the difference in serum vitamin B 12 levels between vegetarian and non-vegetarian pregnant women and multivariate logistic regression for examining the relationship between vegetarian diets and vitamin B 12 deficiency (vitamin B 12<150 pmol/L) in pregnant women. Results:A total of 8 366 pregnant women were included in the analysis, and vegetarians accounted for 1.2% (102/8 366). The median serum vitamin B 12 concentrations were 155.8(93.6-212.4) pmol/L and 187.2(127.4-267.6) pmol/L ( Z=－4.22, P<0.001), and the vitamin B 12 deficiency rates were 48.0% (49/102) and 35.0% (2 896/8 264) in vegetarian and non-vegetarian women, respectively. The vitamin B 12 deficiency rate in vegetarian women was 0.89-fold higher than in non-vegetarians (95% CI: 1.24-2.89). Among the vegetarian and non-vegetarian pregnant women, vitamin B 12 deficiency rates during the first, second, and third trimesters were 34.8%(16/46), 54.3%(19/35), 66.7%(14/21), and 20.4%(521/2 559), 32.6%(941/2 886), 50.9%(1 430/2 807), noting for an increasing trend ( Z=23.54 and 2.57, P=0.010 and P<0.001). Conclusions:Vegetarian pregnant women are at high risk of vitamin B 12 deficiency. Compared with non-vegetarian women, vegetarian pregnant women in China have lower vitamin B 12 levels and a higher risk of vitamin B 12 deficiency. Moreover, the risk of vitamin B 12 deficiency will gradually increase during pregnancy.

Objective:To analyze effects of parity on women′s nutrition and health status.Methods:This study was based on the data bank of "Chinese Nutrition and Health Surveillance of Children and Adolescents Aged 0-17 years old and Lactating Mothers from 2016 to 2017". Using a multi-stage stratified random sampling method, 17 771 women at 0 to 24 months postpartum from 31 provinces in Mainland China were included in this study. Questionnaires were used to collect data on women′s general demographic characteristics, parity, mode of delivery, pre-pregnancy weight, pre-delivery weight, diseases before and during pregnancy, postpartum hemorrhage. Current body height, body weight, waist circumference, and blood pressure were measured. Blood hemoglobin, blood glucose and blood lipids were detected. Pre-pregnancy BMI, gestational weight gain, postpartum weight retention, postpartum BMI, the rates of anemia, hypertension, diabetes, and dyslipidemia were calculated. Survey sample weights were calculated according to the sampling design and number of children under 2 years old from the sixth population census data of China. Effects of parity on the observational indicators after adjusting for confounding factors were analyzed by multivariate linear regression and multivariate logistic regression.Results:The age of 17 771 women was (29.5±5.0) years old, 12.2% (2 172) were over 35 but less than 40 years old, and 3.2% (563) were over 40 years old; the women with one parity, two parities, and three parities accounted for 47.3% (8 413), 48.5% (8 620) and 4.2% (738), respectively; urban women accounted for 49.9% (8 875), and rural women accounted for 50.1% (8 896). The results from multivariate linear regression showed that the pre-pregnancy BMI of women with two and three parities was 0.55 kg/m 2 and 0.76 kg/m 2 higher than women with one parity, respectively; the results of multivariate logistic regression showed that the OR(95% CI) of pre-pregnancy anemia was 1.45(1.04-2.02) for women with three parities compared with women with one parity, and the OR(95% CI) of anemia during pregnancy for women with two parities was 1.20(1.06-1.35) compared with women with one parity. Conclusion:Parity is associated with pre-pregnancy BMI and risk of anemia before and during pregnancy in women of reproductive age.

Objective:To analyze effects of parity on women′s nutrition and health status.Methods:This study was based on the data bank of "Chinese Nutrition and Health Surveillance of Children and Adolescents Aged 0-17 years old and Lactating Mothers from 2016 to 2017". Using a multi-stage stratified random sampling method, 17 771 women at 0 to 24 months postpartum from 31 provinces in Mainland China were included in this study. Questionnaires were used to collect data on women′s general demographic characteristics, parity, mode of delivery, pre-pregnancy weight, pre-delivery weight, diseases before and during pregnancy, postpartum hemorrhage. Current body height, body weight, waist circumference, and blood pressure were measured. Blood hemoglobin, blood glucose and blood lipids were detected. Pre-pregnancy BMI, gestational weight gain, postpartum weight retention, postpartum BMI, the rates of anemia, hypertension, diabetes, and dyslipidemia were calculated. Survey sample weights were calculated according to the sampling design and number of children under 2 years old from the sixth population census data of China. Effects of parity on the observational indicators after adjusting for confounding factors were analyzed by multivariate linear regression and multivariate logistic regression.Results:The age of 17 771 women was (29.5±5.0) years old, 12.2% (2 172) were over 35 but less than 40 years old, and 3.2% (563) were over 40 years old; the women with one parity, two parities, and three parities accounted for 47.3% (8 413), 48.5% (8 620) and 4.2% (738), respectively; urban women accounted for 49.9% (8 875), and rural women accounted for 50.1% (8 896). The results from multivariate linear regression showed that the pre-pregnancy BMI of women with two and three parities was 0.55 kg/m 2 and 0.76 kg/m 2 higher than women with one parity, respectively; the results of multivariate logistic regression showed that the OR(95% CI) of pre-pregnancy anemia was 1.45(1.04-2.02) for women with three parities compared with women with one parity, and the OR(95% CI) of anemia during pregnancy for women with two parities was 1.20(1.06-1.35) compared with women with one parity. Conclusion:Parity is associated with pre-pregnancy BMI and risk of anemia before and during pregnancy in women of reproductive age.

Human milk is the optimal food for infants. We described the history of human milk research both in China and abroad, the gap between domestic and international research, and the future direction in this area. Human milk needs to be studied as a biological system in the future. Reference values for human milk components of Chinese healthy mother-infant dyad should be established. Factors associated with human milk components variations and relationships between human milk components and maternal and child health also need to be investigated to achieve the best nutrition and health status for mother and child pairs.

Breast milk and breastfeeding are the main focus of scientific research on breast milk. Previous studies in the past two centuries have shown that breast milk is the product of human evolution over 200 million years; that breast milk is a gold standard for infant feeding to meet their nutritional requirement, and human milk can also be used clinically for life-saving or health promotion of infants. Breastfeeding is the best way to achieve normal growth and development of infants and maintain their health. The challenges of breastfeeding behavior and the influence of social-economic or other possible factors have contributed to the poor improvement of exclusive breastfeeding rate of infants up to the age of 6 months in the world. Noting the preciseness and urgency of scientific research on human milk, research in the future should focus on the construction of national standard and monitoring system for human milk composition, the establishment of national basic strategic data resources, updating the latest evidence and technological innovation in human milk science, and propose a practical plan to resolve problems in breastfeeding in China.

Objective:To analyze the correlation of phthalate metabolites in neonatal umbilical cord blood with birth indicators in Beijing, 2015.Method:From February to July in 2015, 161 pregnant women and their newborns who met the criteria were recruited from the Maternal and Child Health Hospital in Haidian District, Beijing. Questionnaires were used to collect the demographic information of pregnant women such as age, smoking, drinking, and cord blood after delivery. An ultra-high performance liquid chromatography-tandem mass spectrometry was used to determine the concentration of phthalate metabolites in umbilical cord blood. The multiple linear regression model was used to analyze the correlation of phthalate metabolites in umbilical cord blood with the neonatal weight, length, and ponderal index.Result:The age of 161 pregnant women was (30.3±3.0) years. The weight, length and ponderal index of 161 newborns were (3 447.2±413.0) kg, (50.2±1.1) cm, and (26.7±2.2) kg/m 3; 51.6% of newborns (83 cases) were boys. The concentrations of seven phthalate metabolites detected in umbilical cord blood, i.e., mono-methyl phthalate (MMP), mono-ethyl phthalate (MEP),mono-(2-isobutyl) phthalate (MiBP), mono-n-butyl phthalate (MBP), mono-ethylhexyl phthalate (MEHP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), and mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP), was (3.50±0.28), (2.65±0.47), (4.31±0.55), (6.26±0.57), (1.71±0.13), (1.10±0.09) and (0.47±0.06) ng/ml, respectively. The result of multiple linear regression model analysis showed that the concentrations of seven phthalate metabolites were not related to the neonatal weight, length, and ponderal index (all P values> 0.05). Conclusion:The concentrations of phthalate metabolites in neonatal umbilical cord blood are low, and they are not related to the neonatal weight, length, and ponderal index.