Multiple imputation using auxiliary imputation variables that only predict missingness can increase bias due to data missing not at random.

Background: Epidemiological and clinical studies often have missing data, frequently analysed using multiple imputation (MI). In general, MI estimates will be biased if data are missing not at random (MNAR). Bias due to data MNAR can be reduced by including other variables ("auxiliary variables") in imputation models, in addition to those required for the substantive analysis.

Systematic Review of Clinical Prediction Models for the Risk of Emergency Caesarean Births.

Background: Globally, caesarean births (CB), including emergency caesareans births (EmCB), are rising. It is estimated that nearly a third of all births will be CB by 2030.

Objectives: Identify and summarise the results from studies developing and validating prognostic multivariable models predicting the risk of EmCBs.

Analyses Using Multiple Imputation Need to Consider Missing Data in Auxiliary Variables.

Auxiliary variables are used in multiple imputation (MI) to reduce bias and increase efficiency. These variables may often themselves be incomplete. We explored how missing data in auxiliary variables influenced estimates obtained from MI.

The role of body image dissatisfaction in the relationship between body size and disordered eating and self-harm: complimentary Mendelian randomization and mediation analyses.

Disordered eating and self-harm commonly co-occur in young people suggesting potential for shared underlying causes. Body image dissatisfaction (BID) has been recognised as a psychological correlate of body size, associated with both disordered eating and self-harm. However, the investigation into etiological pathways early in the lifecourse to provide detail on how body size and BID may foster disordered eating and self-harm remains largely unexplored.

Life-course influences of poverty on violence and homicide: 30-year Brazilian birth cohort study.

Background: Homicide is the leading cause of death among young people in Latin America, one of the world's most violent regions. Poverty is widely considered a key cause of violence, but theories suggest different effects of poverty, depending on when it is experienced in the life-course. Longitudinal studies of violence are scarce in Latin America, and very few prospective data are available worldwide to test different life-course influences on homicide.

Evaluation and comparison of nine growth and development-based measures of pubertal timing.

Background: Pubertal timing is heritable, varies between individuals, and has implications for life-course health. There are many different indicators of pubertal timing, and how they relate to each other is unclear. Our aim was to quantitatively compare nine indicators of pubertal timing.

Using instruments for selection to adjust for selection bias in Mendelian randomization.

Selection bias is a common concern in epidemiologic studies. In the literature, selection bias is often viewed as a missing data problem. Popular approaches to adjust for bias due to missing data, such as inverse probability weighting, rely on the assumption that data are missing at random and can yield biased results if this assumption is violated.

Maternal smoking during pregnancy and offspring risk of intellectual disability: a UK-based cohort study.

Background: Observational studies have described associations of maternal smoking during pregnancy with intellectual disability (ID) in the exposed offspring. Whether these results reflect a causal effect or unmeasured confounding is still unclear.

Methods: Using a UK-based prospectively collected birth cohort (the Avon Longitudinal Study of Parents and Children) of 13,479 children born between 1991 and 1992, we assessed the relationship between maternal smoking at 18 weeks' gestation and offspring risk of ID, ascertained through multiple sources of linked information including primary care diagnoses and education records.

Prenatal Urban Environment and Blood Pressure Trajectories From Childhood to Early Adulthood.

Background: Prenatal urban environmental exposures have been associated with blood pressure in children. The dynamic of these associations across childhood and later ages is unknown.

Objectives: The purpose of this study was to assess associations of prenatal urban environmental exposures with blood pressure trajectories from childhood to early adulthood.

Exposure to Violence and Mental Health Outcomes Among Pre-schoolers in a South African Birth Cohort.

Little is known about the relationship between violence exposure and mental health in preschoolers living in low- and middle-income countries (LMICs). Multiple regression analyses investigated associations between violence exposure and mental health in the Drakenstein Child Health Study (N = 978), a South African birth cohort. Lifetime violence exposure was assessed at age 4.

Sleep duration, sleep problems and developmental trajectories of urinary incontinence: a prospective cohort study.

To examine if preschool sleep duration and sleep problems are associated with urinary incontinence (UI) at primary school-age. We used multinomial logistic regression to examine the association of child sleep duration/problems (3½ years) with UI trajectories (4-9 years) in 8751 (4507 boys, 4244 girls) from the Avon Longitudinal Study of Parents and Children. We adjusted for sex, socioeconomic indicators, mothers' emotional/practical/financial support, developmental delay, stressful life events, temperament, and emotional/behaviour problems.

Counterfactual Mediation Analysis with a Latent Class Exposure.

Latent classes are a useful tool in developmental research, however there are challenges associated with embedding them within a counterfactual mediation model. We develop and test a new method "updated pseudo class draws (uPCD)" to examine the association between a latent class exposure and distal outcome that could easily be extended to allow the use of any counterfactual mediation method. UPCD extends an existing group of methods (based on pseudo class draws) that assume that the true values of the latent class variable are missing, and need to be multiply imputed using class membership probabilities.

Air and Noise Pollution Exposure in Early Life and Mental Health From Adolescence to Young Adulthood.

Importance: Growing evidence associates air pollution exposure with various psychiatric disorders. However, the importance of early-life (eg, prenatal) air pollution exposure to mental health during youth is poorly understood, and few longitudinal studies have investigated the association of noise pollution with youth mental health.

Objectives: To examine the longitudinal associations of air and noise pollution exposure in pregnancy, childhood, and adolescence with psychotic experiences, depression, and anxiety in youths from ages 13 to 24 years.

Investigating changes in student mental health and help-seeking behaviour after the introduction of new well-being support services at a UK university.

Background: Growing numbers of students now seek mental health support from their higher education providers. In response, a number of universities have invested in non-clinical well-being services, but there have been few evaluations of these. This research addresses a critical gap in the existing literature.

Emotional problems across development: examining measurement invariance across childhood, adolescence and early adulthood.

Emotional problems (anxiety, depression) are prevalent in children, adolescents and young adults with varying ages at onset. Studying developmental changes in emotional problems requires repeated assessments using the same or equivalent measures. The parent-rated Strengths and Difficulties Questionnaire is commonly used to assess emotional problems in childhood and adolescence, but there is limited research about whether it captures a similar construct across these developmental periods.

Incident psychotic experiences following self-reported use of high-potency cannabis: Results from a longitudinal cohort study.

Background And Aims: High-potency cannabis has been associated with increased risk of psychosis, but a lack of prospective data hinders understanding of causality in this relationship. This study aimed to combine prospective report of cannabis use with retrospective report of potency to infer the potency of cannabis used in adolescence and explore whether use of cannabis, and the use of high-potency cannabis, in adolescence is associated with incident psychotic experiences.

Design: Population-based birth cohort study.

Measures of puberty in the Avon Longitudinal Study of Parents and Children (ALSPAC) offspring cohort.

Background: When studying the development of children through the preteen years into adolescence, it is often important to link features of their physical and mental health to the stage of puberty at the time. This is complex since individuals vary substantially in the ages at which they reach different pubertal milestones.

Methods: The Avon Longitudinal Study of Parents and Children (ALSPAC) is an ongoing longitudinal cohort study based in southwest England that recruited over 14000 women in pregnancy, with expected dates of delivery between April 1991 and December 1992.

Childhood adversities characterize the heterogeneity in the brain pattern of individuals during neurodevelopment.

Background: Several factors shape the neurodevelopmental trajectory. A key area of focus in neurodevelopmental research is to estimate the factors that have maximal influence on the brain and can tip the balance from typical to atypical development.

Methods: Utilizing a dissimilarity maximization algorithm on the dynamic mode decomposition (DMD) of the resting state functional MRI data, we classified subjects from the cVEDA neurodevelopmental cohort ( = 987, aged 6-23 years) into homogeneously patterned DMD (representing typical development in 809 subjects) and heterogeneously patterned DMD (indicative of atypical development in 178 subjects).

Childhood Adversity and Incident Psychotic Experiences in Early Adulthood: Cognitive and Psychopathological Mediators.

Background And Hypothesis: Childhood adversity is often described as a potential cause of incident psychotic experiences, but the underlying mechanisms are not well understood. We aimed to examine the mediating role of cognitive and psychopathological factors in the relation between childhood adversity and incident psychotic experiences in early adulthood.

Study Design: We analyzed data from the Avon Longitudinal Study of Parents and Children, a large population-based cohort study.