Randomised controlled trial of exercise training during lactation on breast milk composition in breastfeeding people with overweight/obesity: a study protocol for the MILKSHAKE trial

Breast milk from people with overweight/obesity may differ in composition compared with that from normal-weight people. Exercise training can modify breast milk composition in rodent models, with a beneficial impact demonstrated on the offspring’s metabolism, but whether these findings translate to humans is unclear. This trial aims to determine the effect of an exercise intervention on breast milk composition and whether an exercise-induced modification of breast milk impacts the infants’ growth and body composition. Effect of Exercise Training on Breastmilk Composition is a randomised, controlled trial with two parallel groups, one exercise group and one control group, with a 1:1 allocation. We will include a minimum of 62 exclusively breastfeeding participants, 6 weeks postpartum. The exercise intervention lasts 8 weeks and comprises 25 supervised endurance exercise sessions with moderate or high intensity. The primary outcome measure is the change in the relative concentration of the human milk oligosaccharide 3′sialyllactose in breast milk from baseline at 6 weeks postpartum to the end of the intervention period. Secondary outcomes include breast milk concentrations of other metabolites, cytokines, hormones and microRNA, maternal health outcomes, infant growth, infant gut microbiome and infant circulating microRNA. Maternal and infant outcomes will be measured before, during and after the intervention period, with a follow-up of the infants until they are 24 months old. Trial registration number NCT05488964

SARS-CoV-2 lineage dynamics in England from September to November 2021: high diversity of Delta sub-lineages and increased transmissibility of AY.4.2

Abstract Background Since the emergence of SARS-CoV-2, evolutionary pressure has driven large increases in the transmissibility of the virus. However, with increasing levels of immunity through vaccination and natural infection the evolutionary pressure will switch towards immune escape. Genomic surveillance in regions of high immunity is crucial in detecting emerging variants that can more successfully navigate the immune landscape. Methods We present phylogenetic relationships and lineage dynamics within England (a country with high levels of immunity), as inferred from a random community sample of individuals who provided a self-administered throat and nose swab for rt-PCR testing as part of the REal-time Assessment of Community Transmission-1 (REACT-1) study. During round 14 (9 September–27 September 2021) and 15 (19 October–5 November 2021) lineages were determined for 1322 positive individuals, with 27.1% of those which reported their symptom status reporting no symptoms in the previous month. Results We identified 44 unique lineages, all of which were Delta or Delta sub-lineages, and found a reduction in their mutation rate over the study period. The proportion of the Delta sub-lineage AY.4.2 was increasing, with a reproduction number 15% (95% CI 8–23%) greater than the most prevalent lineage, AY.4. Further, AY.4.2 was less associated with the most predictive COVID-19 symptoms (p = 0.029) and had a reduced mutation rate (p = 0.050). Both AY.4.2 and AY.4 were found to be geographically clustered in September but this was no longer the case by late October/early November, with only the lineage AY.6 exhibiting clustering towards the South of England. Conclusions As SARS-CoV-2 moves towards endemicity and new variants emerge, genomic data obtained from random community samples can augment routine surveillance data without the potential biases introduced due to higher sampling rates of symptomatic individuals. </jats:sec