Objective To synthesise evidence from contemporary populations (2009-24) across diverse world regions and income settings on associations between gestational weight gain (GWG) and broad clinical outcomes, to inform updated, globally relevant GWG standards. Design Systematic review and meta-analysis. Setting Observational studies in all languages, with >300 participants, reporting pregnancy outcomes stratified by body mass index (BMI) and GWG. Participants Women aged >18 years with singleton pregnancies. Main outcome measures Birth weight and rates of caesarean delivery, hypertensive disorders of pregnancy, preterm birth, small/large for gestational age infant, low birth weight, macrosomia, neonatal intensive care unit (NICU) admission, respiratory distress, hyperbilirubinaemia, and gestational diabetes. Results Of 16 030 studies, 40 met inclusion criteria (n=1 608 711); 6% (n=65 114) of women had underweight, 53% (n=607 258) had normal weight, 19% (n=215 183) had overweight, and 22% (n=252 970) had obesity. GWG was below or above Institute of Medicine (IOM) or study specific recommendations in 23% and 45%, respectively. Using World Health Organization BMI criteria, GWG below IOM recommendations was associated with lower birth weight (mean difference −184.54, 95% confidence interval −278.03 to −91.06); lower risk of caesarean delivery (odds ratio 0.90, 0.84 to 0.97), large for gestational age infant (0.67, 0.61 to 0.74), and macrosomia (0.68, 0.58 to 0.80); and higher risk of preterm birth (1.63, 1.33 to 1.90), small for gestational age infant (1.49, 1.37 to 1.61), low birth weight (1.78, 1.48 to 2.13), and respiratory distress (1.29, 1.01 to 1.63). GWG above IOM recommendations was associated with higher birth weight (mean difference 118.33, 53.80 to 182.85); higher risk of caesarean delivery (odds ratio 1.37, 1.30 to 1.44), hypertensive disorders of pregnancy (1.37, 1.28 to 1.48), large for gestational age infant (1.77, 1.62 to 1.94), macrosomia (1.78, 1.60 to 1.99), and NICU admission (1.26, 1.09 to 1.45); and lower risk of preterm birth (0.71, 0.64 to 0.79) and small for gestational age infant (0.69, 0.64 to 0.75). For Asian BMI criteria, GWG below recommendations was associated with higher risk of hypertensive disorders of pregnancy (3.58, 1.37 to 9.39) and preterm birth (1.69, 1.25 to 2.30) and lower risk of large for gestational age infant (0.80, 0.72 to 0.89). GWG above recommendations was associated with higher risk of caesarean delivery (1.37, 1.29 to 1.46) and large for gestational age infant (1.76, 1.42 to 2.18) and lower risk of small for gestational age infant (0.62, 0.53 to 0.74) and low birth weight (0.44, 0.31 to 0.6). Conclusions This systematic review captured trends of rising maternal age and BMI from diverse world regions and income settings, with broad outcomes across all BMI groups. GWG outside IOM recommendations was associated with increased risk of adverse outcomes. These findings will help to inform the process of the WHO initiative to optimise globally relevant GWG standards for improved perinatal outcomes across world regions. Study registration PROSPERO CRD42023483168.

Postpartum women experience unique barriers to maintaining healthy lifestyles after birth. Theory-based behaviour change techniques and intervention strategies can be integrated into postpartum lifestyle interventions to enable women to overcome barriers to change. This study aims to explore barriers and facilitators to engaging in healthy postpartum lifestyle behaviours and develop intervention strategies for integration in a postpartum lifestyle intervention using the Behaviour Change Wheel (BCW). Semi-structured interviews were conducted with women up to two years postpartum (n = 21). Interviews were thematically analysed, themes were mapped to the Capability, Opportunity, and Motivation Model of Behaviour Change and intervention strategies were developed using the BCW. Findings suggest that women face barriers and facilitators within capability (sleep deprivation, mental exhaustion, ability to plan), opportunity (support of friends, partners and extended families) and motivation (challenges with prioritising self, exercise to cope with stress). Intervention strategies included supporting behaviour regulation and sleep to enhance capability, engaging partners, strengthening peer support to create opportunities and highlighting the mental health benefits of healthy lifestyles to inspire motivation. Integrating targeted evidence-based behaviour change strategies into postpartum lifestyle interventions may support women in overcoming commonly reported barriers to a healthy lifestyle.

Aim: Social media platforms are being increasingly used to support participant recruitment into paediatric health‐related research. This study aimed to develop a multi‐phase approach for using social media as a recruitment strategy for paediatric research studies.Methods: The process was informed by the authors’ prior experiences recruiting for paediatric obesity‐related research studies, expertise in social media marketing and digital participant/ patient recruitment. Reflection on these experiences resulted in the iterative creation of a draft process which was further refined. A narrative literature review using a structured search was conducted to refine and augment the content and finalise the process.Results: A six‐phase recruitment approach was developed that includes: (i) plan for social media use as a recruitment strategy, (ii) explore relevant ethical considerations to protect the wellbeing of potentially vulnerable groups and create an ethical management plan, (iii) identify and understand the different target audiences and develop the advertising strategy, (iv) develop and design campaign content, (v) implement, monitor and iteratively refine the recruitment campaign, (vi) evaluate the campaign success. Potential activities and key considerations relevant for paediatric research are presented within each phase.Conclusion: Due to the widespread use and diverse characteristics of social media users, social media has the potential to disseminate details of research opportunities to community members who may otherwise not hear about, engage with, and potentially benefit from research participation. Researchers should collaborate with communication experts and target audiences to generate relevant and effective recruitment campaigns. Researchers should implement processes to protect vulnerable audiences’ wellbeing at each stage of the process. Recruitment via social media may support wider community participation in research studies designed to improve young people's health.

The aim of this study was to determine the efficacy, safety and acceptability of a 4-week very-low-energy diet (VLED) program for adolescents with obesity. Adolescents (13–17 years) with obesity and ≥1 obesity-related complication were Fast Track to Health 52-week randomized controlled trial participants. Adolescents undertook a 4-week micronutrient-complete VLED (800 kcal/day), with weekly dietitian support. Anthropometric data were recorded at baseline and week-4 and side-effects at day 3–4, week-1, -2, -3 and -4. Adolescents completed an acceptability survey at week-4. A total of 134 adolescents (14.9 ± 1.2 years, 50% male) had a 5.5 ± 2.9 kg (p < 0.001) mean weight loss at week-4: 95% experienced ≥1 and 70% experienced ≥3 side-effects during the VLED program, especially during the first week. Hunger, fatigue, headache, irritability, loose stools, constipation and nausea were most common. Reporting more side-effects at day 3–4 correlated with greater weight loss at week-4 (r = −0.188, p = 0.03). Adolescents reported ‘losing weight’ (34%) and ‘prescriptive structure’ (28%) as the most positive aspects of VLED, while ‘restrictive nature’ (45%) and ‘meal replacement taste’ (20%) were least liked. A dietitian-monitored short-term VLED can be implemented safely and is acceptable for many adolescents seeking weight loss, despite frequent side-effects. Investigating predictors of acceptability and effectiveness could determine adolescents most suited to VLED programs.