Background Biological signaling and communication between mothers and infants during breastfeeding may shape infant behavior and feeding. This signaling is complex and little explored in humans, although it is potentially relevant for initiatives to improve breastfeeding rates. Objectives The aim of this study was to investigate physiological and psychological aspects of mother–infant signaling during breastfeeding experimentally, testing the effects of a relaxation intervention on maternal psychological state, breast milk intake, milk cortisol levels, and infant behavior and growth. Methods Primiparous breastfeeding mothers and full-term infants were randomly assigned to receive relaxation therapy [intervention relaxation group; n = 33 (RG)] or to the control group [n = 31 (CG); no relaxation therapy] at 2 wk postpartum. Both groups received standard breastfeeding support. Home visits were conducted at 2 (HV1), 6 (HV2), 12 (HV3) and 14 (HV4) wk to measure maternal stress and anxiety, breast milk intake and milk cortisol, and infant behavior and growth. Results RG mothers had lower stress scores postintervention than the CG (HV3 ∆ = −3.13; 95% CI: −5.9, −0.3) and lower hindmilk cortisol at HV1 (∆ = −44.5%; 95% CI: −76.1%, −12.9%) but not at HV2. RG infants had longer sleep duration (∆ = 82 min/d; 95% CI: 16, 149 min/d) at HV2 and higher gains in weight and body mass index standardized deviation score than the CG infants (∆ = 0.76; 95% CI: 0.3, 1.22; and ∆ = 0.59; 95% CI: 0.09, 1.1, respectively). RG infants had a mean milk intake at HV3 that was 227 g/d higher than that of the CG infants (P = 0.031) after controlling for gender and milk intake at HV1. Conclusions The trial shows the effectiveness of a simple relaxation intervention for improving maternal and infant outcomes and identifies some potential signaling mechanisms for investigation in future and larger studies, especially in settings where mothers are more stressed, such as those with preterm or low birth weight infants. This trial was registered at clinicaltrials.gov as NCT01971216.

Iodine deficiency during pregnancy and lactation may adversely affect fetal and infant development. Two initiatives were introduced in New Zealand to prevent deficiency: (1) mandatory fortification of bread with iodised salt; and (2) provision of a subsidised iodine supplement (150 μg) for all pregnant and breastfeeding women. The aim of this study was to assess iodine intake and status among a self-selecting sample of pregnant and lactating women in Palmerston North, both before and after the two initiatives. Pregnant and breastfeeding women were recruited before (n = 25 and 32; 2009) and after (n = 34 and 36; 2011) the initiatives. Iodine concentration was determined in 24-h urine and breast milk samples using inductively-coupled plasma mass spectrometry. Use of supplements and salt, knowledge of iodine deficiency, and awareness of the initiatives were determined by questionnaire. Median urine iodine concentration (UIC) was higher in 2011 compared with 2009 for both pregnant (85 and 47 μg L(-1) ) and breastfeeding (74 and 34 μg L(-1) ) participants; median UIC were below the cut-offs for adequate iodine status. However, in 2011, the estimated daily iodine intake during pregnancy was 217 μg day(-1) ; 74% of women achieved the Estimated Average Requirement. Knowledge of the initiatives was low, only 28-56% were aware of the need for iodine supplements and only 15-22% were aware of the mandatory addition of iodised salt to bread. Despite initiatives, UIC of these women indicates iodine deficiency, however, dietary intakes appear adequate. Ongoing surveillance of supplement use and iodine status among pregnant and lactating women throughout New Zealand is needed to fully assess the efficacy of the initiatives. Alternative strategies may require evaluation to ensure all women have adequate iodine during pregnancy and breastfeeding.

Background: Promoting breastfeeding is an important public health intervention, with benefits for infants and mothers. Even modest increases in prevalence and duration may yield considerable economic savings. However, despite many initiatives, compliance with recommendations is poor in most settingsparticularly for exclusive breastfeeding. Mothers commonly consult health professionals for infant feeding and behavioural problems. Main body: We argue that broader consideration of lactation, incorporating evolutionary, comparative and anthropological aspects, could provide new insights into breastfeeding practices and problems, enhance research and ultimately help to develop novel approaches to improve initiation and maintenance. Our current focus on breastfeeding as a strategy to improve health outcomes must engage with the evolution of lactation as a flexible trait under selective pressure to maximise reproductive fitness. Poor understanding of the dynamic nature of breastfeeding may partly explain why some women are unwilling or unable to follow recommendations. Conclusions: We identify three key implications for health professionals, researchers and policymakers. Firstly, breastfeeding is an adaptive process during which, as in other mammals, variability allows adaptation to ecological circumstances and reflects mothers' phenotypic variability. Since these factors vary within and between humans, the likelihood that a 'one size fits all' approach will be appropriate for all mother-infant dyads is counterintuitive; flexibility is expected. From an anthropological perspective, lactation is a period of tension between mother and offspring due to genetic 'conflicts of interest'. This may underlie common breastfeeding 'problems' including perceived milk insufficiency and problematic infant crying. Understanding thisand adopting a more flexible, individualised approachmay allow a more creative approach to solving these problems. Incorporating evolutionary concepts may enhance research investigating mother-infant signalling during breastfeeding; where possible, studies should be experimental to allow identification of causal effects and mechanisms. Finally, the importance of learned behaviour, social and cultural aspects of primate (especially human) lactation may partly explain why, in cultures where breastfeeding has lost cultural primacy, promotion starting in pregnancy may be ineffective. In such settings, educating children and young adults may be important to raise awareness and provide learning opportunities that may be essential in our species, as in other primates.

Maternal psychological state is recognised to influence lactation success, largely by affecting milk ejection. Thus, increased psychological distress can disrupt milk flow and in the long‐term, affect milk synthesis. Conversely, it is possible that milk ejection could be improved by using relaxation therapy during breastfeeding. We performed a systematic review to evaluate the effectiveness of interventions using relaxation therapy to improve breastfeeding outcomes and to assess the consequent impact(s) on infant growth and behaviour. A literature search was performed using the PRISMA guidelines where we included intervention studies (including nonrandomised controlled studies) using relaxation therapy in breastfeeding mothers during the post‐natal period. Out of 147 identified records at the initial search, 5 studies were eligible, of which 3 were randomised controlled trials and 2 were nonrandomised or quasi‐experimental studies. These studies were conducted in Europe, America, and India and included 311 mother–infant pairs, of which 64 infants were full‐term and 247 were premature infants. Relaxation therapy was shown to increase milk yield in mothers of preterm infants in 2 randomised trials, however, the milk sampling protocol for these studies could be questioned. None of the studies investigated the consequent effects on infant outcomes. Overall, limited evidence was found on the effectiveness of relaxation therapy on breast milk composition and infant outcomes. Experimental studies with better standardisation of protocol and robust methodological design are needed to investigate the effectiveness of relaxation therapy on both breastfeeding and infant growth and behavioural outcomes.

Overweight and obesity are becoming increasingly prevalent among children and adolescents in Saudi Arabia and are an emerging cause of non-communicable diseases (NCDs). Lifestyle factors, such as insufficient levels of physical activity and sedentary behaviors, are responsible for the increased prevalence of NCDs. This study aimed to determine the association between physical activity levels, sedentary behaviors, and anthropometric measurements in Saudi female adolescents. A cross-sectional study was carried out among 399 healthy female adolescent students aged 13–14 years in Arar, Saudi Arabia. The participants were randomly selected from different schools and their anthropometric measurements were determined. The Physical Activity Questionnaire for Older Children (PAQ-C) and the Adolescent Sedentary Activity Questionnaire (ASAQ) were used to assess their physical activity levels and sedentary behaviors, and an analysis was conducted using IBM SPSS software version 25. A multiple linear regression model was used to determine the association between the variables. The majority of the participants had a normal body mass index (BMI; 79.4%) and waist circumference (WC; 62.4%). A total of 74.4% had waist to height ratio (WHtR) < 0.5. About 92.7% of the participants were not meeting PA recommendations of 60 min of moderate to vigorous physical activity daily. The overall mean time spent on sedentary activities was high on both weekdays and weekend days at 357.64 ± 86.29 and 470.51 ± 147.64 min/day, respectively. Moreover, anthropometric measurement (BMI) was positively associated with age and negatively associated with sedentary behavior on weekends, while WHtR was positively associated with age. The multiple linear regression analysis also showed that age and sedentary behavior significantly predicted BMI among the study participants (F (2, 396) = 4.346, p < 0.014) and age was the only significant predictor of WHtR (F (1, 397) = 16.191, p ≤ 0.001). This study revealed that most of the female Saudi adolescents undertook low levels of activity and high levels of sedentary behaviors. Sedentary behaviors were significantly associated with their BMI. Accordingly, an intervention program on healthy lifestyles is important to improve Saudi female adolescents’ lifestyles.

BackgroundThe physiological and psychological signalling between mother and infant during lactation is one of the prominent mother-infant factors that may influence breastfeeding outcomes. The infant can ‘signal’ his needs through vocalisation, and the mother can respond by allowing or restricting nipple access, which might alter the breast milk composition or volume. This may lead to parent-offspring conflict during the lactation period. Challenging infant behaviour has also been associated with maternal psychological distress, which might affect breastfeeding performance. Most attempts to improve breastfeeding rates focus on providing additional support, yet many aspects of the breastfeeding process are poorly understood. Thus, our objective is to investigate mother-infant signalling during breastfeeding by manipulating maternal psychological state using a relaxation therapy intervention. The study will test the hypothesis that mothers who listen to the therapy will be more relaxed/less stressed and this will favourably alter breast milk composition and/or affect milk volume and hence influence infant outcomes.MethodsA randomised controlled trial will be conducted in first-time breastfeeding mothers and their new-born infants. Pregnant mothers will be recruited at antenatal clinics in Selangor, Malaysia, and four home visits will be carried out at 2, 6, 12 and 14 weeks postnatally. Participants will be randomised into a control and an intervention group in the early post-partum period. Mothers from the intervention group will be asked to listen daily to an audio recording with relaxation therapy during breastfeeding. Maternal psychological state, breastfeeding practices and infant behaviour will be assessed using validated questionnaires. Milk volume will be measured using stable isotopes. Breast milk samples will be collected to measure macronutrient content and hormone levels. Anthropometric measurements (weight, length and head circumference) will be performed during all home visits, including body composition at week 14.DiscussionThe main outcomes will be the effect of the intervention on maternal psychological state, milk production, cortisol levels, and infant behaviour and growth. Secondary outcomes will be associations between breast milk composition and infant appetite and growth. This study aims to provide a greater understanding of maternal-infant factors which influence breastfeeding outcomes and which may be useful targets for future interventions.Trial registration ClinicalTrials.gov identifier: NCT01971216.

j school of Human evolution and social Change, arizona state university, tempe, arizona, usa; k swammerdam institute for life sciences, Center for neuroscience, Brain Plasticity group, university of amsterdam, amsterdam, the netherlands; l department of nutrition, Faculty of Medicine and Health sciences, universiti Putra Malaysia, selangor, Malaysia; m department of women & Children's Health, King's College london, st thomas' Hospital, london, uK; n school of Hygiene and tropical Medicine, nutrition theme, MrC unit the Gambia and the london, Fajara, the GambiaBanjul; o the liggins institute, the university of auckland, auckland, new Zealand; p department of nutrition and Food science,

Background: Circadian rhythm plays an important role as our internal body's clock that synchronizes behavior and physiology according to the external 24-h light-dark cycle. Past studies have associated disrupted circadian rhythm with higher risk of miscarriages, preterm birth and low birth weights. This paper described the protocol of a prospective cohort study which aims to determine the circadian rhythm in pregnant women, identify its association with maternal factors during pregnancy, gestational weight gain, birth and infant outcomes. Methods: Ten government maternal and child health clinics in Kuala Lumpur, Malaysia will be randomly selected. Sample size of 438 first-trimester pregnant women will be followed-up until the birth of their infant. Salivary melatonin and cortisol concentration among subsample will be determined using enzyme-linked immunosorbent assay. Data on sleep quality, psychological distress and morningness/eveningness chronotype of pregnant women will be collected using validated questionnaires. Pedometer will be used to measure 5-day physical activity data. Total gestational weight gain will be determined at the end of pregnancy. Utilization of 3-day food record is to capture meal timing and nutrient intake. All measurements will be done in 2nd and 3rd trimester. Birth outcomes will be collected through clinic records and Centers for Disease Control and Prevention (CDC) Neonatal questionnaire. Infants will be followed-up at 6 and 12 months old to obtain anthropometric measurements. Discussion: There is a growing recognition of the role of maternal circadian rhythm, which entrains fetal circadian rhythms that may subsequently have long-term health consequences. The present study will identify the effect of circadian rhythm on pregnancy outcomes and infant growth in the first year of life.