The Effect of Physical Activity on Human Milk Macronutrient Content and Its Volume

Clinical and exercise professional opinion on designing a postpartum return-to-running training programme: an international Delphi study and consensus statement

Returning to running postpartum presents challenges such as musculoskeletal pain and pelvic floor dysfunction for some females, but there is little guidance on developing and progressing postpartum training programmes. This study aims to establish expert consensus recommendations on designing and modifying a postpartum return-to-running training programme, highlight costs and access to qualified professionals as potential barriers and discuss clinical, research and sports policy implications.A three-round Delphi survey of clinical and exercise professionals working with postpartum runners was conducted. Round I consisted of open-ended questions related to designing the training plan, modifications based on biopsychosocial factors, key muscle groups to train and referral and payment sources. Rounds II and III involved Likert-scale voting to identify consensus (≥75% agreement).118 participants completed Round I, 107 completed Round II (response rate 90.6%) and 95 completed Round III (response rate 80.5%). Consensus was reached in 42/47 (89%) statements, including recommendations for a period of relative rest, gradual increases in duration and intensity, starting with a walk-run protocol and incorporating strength training. Training should be modified based on musculoskeletal or pelvic symptoms, sleep, mental health, lactation or energy availability concerns. Cost and access to experienced postpartum running professionals were identified as potential barriers for runners to receive care.Consensus recommendations for a postpartum return-to-running programme include an individualised exercise prescription, gradual increases in physical activity, walk-run protocols and targeted muscle strengthening. Further research and improved access to clinical and exercise professionals are needed to inform and facilitate best practices.

After Theranos: Using point-of-care testing to advance measures of health biomarkers in human biology research

OBJECTIVES

The rise and fall of the health technology startup Theranos is emblematic of the promise and peril of point-of-care testing (POCT). Instruments that deliver immediate results from minimally invasive samples at the location of collection can provide powerful tools to deliver health data in clinical and public health contexts. Yet, POCT availability is driven largely by market interests, which limits the development of inexpensive tests for diverse health conditions that can be used in resource-limited settings. These constraints, combined with complex regulatory hurdles and substantial ethical challenges, have contributed to the underutilization of POCT in human biology research.

METHODS

We evaluate current POCT capabilities and limitations, discuss promising applications for POCT devices in resource-limited settings, and discuss the future of POCT.

RESULTS

As evidenced by publication trends, POCT platforms have rapidly advanced in recent years, gaining traction among clinicians and health researchers. We highlight POCT devices of potential interest to population-based researchers and present specific examples of POCT applications in human biology research.

CONCLUSIONS

Several barriers can limit POCT applications, including cost, lack of regulatory approval for non-clinical use, requirements for expensive equipment, and the dearth of validation in remote field conditions. Despite these issues, we see immense potential for emerging POCT technology capable of analyzing new sample types and used in conjunction with increasingly common technology (e.g., smart phones). We argue that the fallout from Theranos may ultimately provide an opportunity to advance POCT, leading to more ethical data collection and novel opportunities in human biology research.

Cohort profile: Japanese human milk study, a prospective birth cohort: baseline data for lactating women, infants and human milk macronutrients

PURPOSE

The Japanese Human Milk Study, a longitudinal prospective cohort study, was set up to clarify how maternal health, nutritional status, lifestyle and sociodemographic and economic factors affect breastfeeding practices and human milk composition. This would eventually determine factors affecting the growth and development of infants and children.

PARTICIPANTS

A total of 1210 Japanese lactating women who satisfied the inclusion criteria, were invited across the country at various participating sites, between 2014 and 2019. Finally a total of 1122 women were enrolled in this study.

FINDINGS TO DATE

Among 1122 eligible participants, mean age at delivery was 31.2 (SD 4.4) years and mean prepregnancy BMI was 20.8 (SD 2.7). Among these women, 35% were previously nulliparous and 77.7% had college, university or higher education. The mean gestational period was 39.0 (SD 1.3) weeks. Caesarean section was reported among 11.9%; mean infant birth weight was 3082 (SD 360) g. Of the infants, 53.7% were male. Overall, our participants appeared to be healthier than the general population in Japan. Analyses of the 1079 eligible human milk samples obtained at the first and second months postpartum showed the following composition: carbohydrate, 8.13 (SD 0.32) g/100 mL; fat, 3.77 (SD 1.29) g/100 mL; and crude protein, 1.20 (SD 0.23) g/100 mL. We also analysed osteopontin, fatty acid, vitamin D and phospholipid levels in limited subcohorts of the samples.

FUTURE PLANS

Follow-up surveys will be conducted to obtain milk samples every 2 months for 12 months and to investigate mother and child health until the children reach 5 years of age. These will be completed in 2024. We plan to longitudinally analyse the composition of macronutrients and various bioactive factors in human milk and investigate the lifestyle and environmental factors that influence breastfeeding practices, maternal and child health, and child development.

TRIAL REGISTRATION NUMBER

UMIN000015494; pre-results.

Investigation of the Effect of Human Milk Expression Techniques on Milk Content: A Systematic Review

BACKGROUND

If the mother and infant cannot meet after birth, it is recommended to express milk and give it to the infant. There was evidence indicating that there might be decrease in essential nutrient values in human milk content depending on the expression technique in literature. The goal of this systematic review was to investigate the effect of human milk expression techniques on the macronutrient milk content and establish an evidence base for future studies.

METHODS

Studies investigating the effect of human milk expression techniques on milk content were reviewed without year limitations. A literature review was conducted in six electronic databases (MEDLINE, Web of Science, PubMed, ScienceDirect, CINAHL and Cochrane) until 30 May 2021, using the keywords of breast milk expression techniques, milk content and breast milk pumping.

RESULTS

From 258 articles initially screened, we included 6 articles in the systematic review. The fat, protein and lactose content of human milk was analyzed in the studies reviewed. It was concluded that there was no significant effect on the protein (9.7-9.8 g/dl and 2.1-2.1 g/dl, respectively) and lactose (6.50-6.53% and 6.1-6.1 g/dl, respectively) content of milk. However, the fat (58.30, 48.81g/l; 2.6-2.2 g/dl) content was affected.

CONCLUSIONS

This study investigated the effect of milk expression techniques on the macronutrient content of human milk, and it was concluded that there was no significant effect on the protein and carbohydrate content of milk. However, the fat content was affected. Limitation of this study is that some factors that might affect the content of human milk were not standardized sufficiently in the included studies.

Tandem Breastfeeding and Human Milk Macronutrients: A Prospective Observational Study

BACKGROUND

Tandem breastfeeding is defined as two or more offspring of different ages who are breastfed by their mother at the same time. Breastfeeding during pregnancy and tandem breastfeeding have not been widely investigated.

RESEARCH AIM

To determine the influence of tandem breastfeeding on the macronutrient content of human milk.

METHODS

This longitudinal study used a prospective and a retrospective group. Human milk samples from tandem-breastfeeding participants (n = 18) were compared to samples from non-tandem-breastfeeding participants (n = 31). Samples were collected during the last month of pregnancy (pregnancy milk), 72 hr after birth (colostrum) and 14-60 days post-delivery (mature milk). Macronutrients were measured by mid-infrared spectroscopy.

RESULTS

Fat content in pregnancy milk was lower than in mature milk (p < .01). Protein content was higher in pregnancy milk than in colostrum and mature milk (p < .01 and p < .001, respectively). Inversely, carbohydrate content in pregnancy milk was lower than in colostrum and mature milk (p = .02 and p < .01, respectively). Fat and energy contents in pregnancy milk of tandem-breastfeeding participants were lower than in mature milk of non-tandem-breastfeeding participants (p < .001 and p < .01, respectively), and protein content was higher than in mature milk (p < .001). Carbohydrate content in colostrum and mature milk of tandem-breastfeeding participants was higher than that of non-tandem-breastfeeding participants (p < .001 for both).

CONCLUSION

Human milk produced during pregnancy had different macronutrient content than human milk produced after delivery. Colostrum and mature milk of tandem-breastfeeding participants were similar to human milk produced by non-tandem-breastfeeding participants, with the exception of carbohydrate content.

Maternal BMI is positively associated with human milk fat: a systematic review and meta-regression analysis

BACKGROUND

Lack of robust estimates of human-milk nutrient composition and influential maternal factors, such as body composition, are barriers to informing nutrition policies and programs.

OBJECTIVE

The objective was to understand the relation between maternal BMI and human-milk energy, fat, and/or total protein.

METHODS

Four electronic databases (MEDLINE, Embase, CINAHL, and Web of Science) were searched. Outcomes assessed were human-milk energy (kcal/L), fat (g/L), and total protein (g/L) from mothers 1 to 6 mo postpartum. Studies with data on maternal BMI or weight and height that quantified human-milk energy, fat, or protein between 1 and 6 mo postpartum were eligible. Random-effects meta-regression weighted by the inverse of the study-level SE was completed for each of the 3 outcomes. The certainty of evidence for each outcome was assessed using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach.

RESULTS

A total of 11,373 titles and abstracts were identified, and after full-text screening, 69 articles of 66 studies were included. Meta-regression results showed a positive association between maternal BMI and human-milk fat (β: 0.56 g/L; 95% CI: 0.034, 1.1; P = 0.04; I2 = 93.7%, n = 63 datapoints). There was no significant association between maternal BMI and human-milk energy (β: 3.9 kcal/L; 95% CI: -1.6, 9.5; P = 0.16, I2 = 93.3%, n = 40 datapoints) or total protein (β: 0.13 g/L; 95% CI: -0.16, 0.41; P = 0.37, I2 = 99.1%, n = 40 datapoints). The certainty of evidence for human-milk energy was low and the certainty of evidence for fat and total protein was very low.

CONCLUSIONS

Meta-regression analysis of available literature suggested an association between maternal BMI and human-milk fat between 1 and 6 mo postpartum. Future studies are needed to confirm the relation between maternal BMI; variation in human-milk energy, fat, and protein content; and the implications for child growth and development. This review is registered with International Prospective Register of Systematic Reviews (PROSPERO 2018 CRD42018098808) at https://www.crd.york.ac.uk/prospero/.

The Effect of Infant's Sex on Human Milk Macronutrients Content: An Observational Study

Background: Sex differences in infant mortality and neonatal morbidity have been previously documented. Few studies, with conflicting results, have investigated the interaction between human milk (HM) macronutrients and energy content and infant sex. Objective: To test the null hypothesis that HM macronutrients content will not be affected by infant's sex. Materials and Methods: We compiled previously generated data on macronutrients content of colostrum samples and mature milk samples collected from lactating mothers of healthy term infants. Macronutrient content was measured using mid-infrared spectroscopy. Results: A total of 324 milk samples were included in the analysis consisting of 189 colostrum and 135 mature milk samples. There were 92 female and 97 male infants in the colostrum group and 65 female and 70 male infants in the mature milk group. Maternal age, gestational age, mode of delivery and percentage of large for gestational age, small for gestational age, and appropriate for gestational age were similar between female and male groups at all stages of lactation. Birth weight in male infants was significantly higher than in female infants (3389.5 ± 444.6 versus 3229.2 ± 415 g, p = 0.016). There were no statistically significant differences in macronutrient contents between the female and male groups at all stages studied. Conclusion: Macronutrients and energy content in colostrum and mature milk collected from mothers of term infants were unaffected by the sex of their offspring.