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Key Points: Question: Is the association between lower birth weight and offspring neurodevelopmental difficulties causal? Findings: In this conventional epidemiological cohort study of 46 970 offspring, lower birth weight was associated with neurodevelopmental difficulties across various offspring ages. However, mendelian randomization causal analyses of 44 134 mother-child dyads did not find evidence for a causal association between intrauterine growth (with maternal genetic factors influencing fetal growth as a proxy) and offspring neurodevelopmental difficulties. Meaning: This study found that maternal factors influencing intrauterine growth do not appear to drive the observational association between lower birth weight and offspring neurodevelopmental difficulties. Importance: Conventional epidemiological analyses have suggested that lower birth weight is associated with later neurodevelopmental difficulties; however, it is unclear whether this association is causal. Objective: To investigate the relationship between intrauterine growth and offspring neurodevelopmental difficulties. Design, Setting, and Participants: MoBa is a population-based pregnancy cohort that recruited pregnant women from June 1999 to December 2008 included approximately 114 500 children, 95 200 mothers, and 75 200 fathers. Observational associations between birth weight and neurodevelopmental difficulties were assessed with a conventional epidemiological approach. Mendelian randomization analyses were performed to investigate the potential causal association between maternal allele scores for birth weight and offspring neurodevelopmental difficulties conditional on offspring allele scores. Exposures: Birth weight and maternal allele scores for birth weight (derived from genetic variants robustly associated with birth weight) were the exposures in the observational and mendelian randomization analyses, respectively. Main Outcomes and Measures: Clinically relevant maternal ratings of offspring neurodevelopmental difficulties at 6 months, 18 months, 3 years, 5 years, and 8 years of age assessing language and motor difficulties, inattention and hyperactivity-impulsivity, social communication difficulties, and repetitive behaviors. Results: The conventional epidemiological sample included up to 46 970 offspring, whereas the mendelian randomization sample included up to 44 134 offspring (median offspring birth year, 2005 [range, 1999-2009]; mean [SD] maternal age at birth, 30.1 [4.5] years; mean [SD] paternal age at birth, 32.5 [5.1] years). The conventional epidemiological analyses found evidence that birth weight was negatively associated with several domains at multiple offspring ages (outcome of autism-related trait scores: Social Communication Questionnaire [SCQ]–full at 3 years, β = −0.046 [95% CI, −0.057 to −0.034]; SCQ–Restricted and Repetitive Behaviors subscale at 3 years, β = −0.049 [95% CI, −0.060 to −0.038]; attention-deficit/hyperactivity disorder [ADHD] trait scores: Child Behavior Checklist [CBCL]–ADHD subscale at 18 months, β = −0.035 [95% CI, −0.045 to −0.024]; CBCL-ADHD at 3 years, β = −0.032 [95% CI, −0.043 to −0.021]; CBCL-ADHD at 5 years, β = −0.050 [95% CI, −0.064 to −0.037]; Rating Scale for Disruptive Behavior Disorders [RS-DBD]–ADHD at 8 years, β = −0.036 [95% CI, −0.049 to −0.023]; RS-DBD–Inattention at 8 years, β = −0.037 [95% CI, −0.050 to −0.024]; RS-DBD–Hyperactive-Impulsive Behavior at 8 years, β = −0.027 [95% CI, −0.040 to −0.014]; Conners Parent Rating Scale–Revised [Short Form] at 5 years, β = −0.041 [95% CI, −0.054 to −0.028]; motor scores: Ages and Stages Questionnaire–Motor Difficulty [ASQ-MOTOR] at 18 months, β = −0.025 [95% CI, −0.035 to −0.015]; ASQ-MOTOR at 3 years, β = −0.029 [95% CI, −0.040 to −0.018]; and Child Development Inventory–Gross and Fine Motor Skills at 5 years, β = −0.028 [95% CI, −0.042 to −0.015]). Mendelian randomization analyses did not find any evidence for an association between maternal allele scores for birth weight and offspring neurodevelopmental difficulties. Conclusions and Relevance: This study found that the maternal intrauterine environment, as proxied by maternal birth weight genetic variants, is unlikely to be a major determinant of offspring neurodevelopmental outcomes. This cohort study investigates the association between lower birth weight and neurodevelopmental difficulties, as well as the causal association of intrauterine growth with measures of offspring neurodevelopmental difficulties. [ABSTRACT FROM AUTHOR]

Importance: Several maternal exposures during pregnancy are considered predisposing factors for offspring neurodevelopmental conditions. However, many of these exposures may be noncausal and biased by maternal genetic liability.Objective: To assess whether pregnancy-related predisposing factors for offspring neurodevelopmental conditions are associated with maternal genetic liability for attention-deficit/hyperactivity disorder (ADHD), autism, and schizophrenia and to compare associations for maternal genetic liability with those for paternal genetic liability, which could indicate that paternal exposures are not suitable negative controls for maternal exposures.Design, Setting, and Participants: The Norwegian Mother, Father and Child Cohort Study (MoBa) is a population-based pregnancy cohort that recruited parents from June 1999 to December 2008. Polygenic scores (PGS) for ADHD, autism, and schizophrenia were derived in mothers and fathers. The associations between maternal PGS and 37 pregnancy-related measures were estimated, and these results were compared with those from paternal PGS predicting paternal measures during the mother's pregnancy. Analysis took place between March 2021 and March 2022.Exposures: PGS for ADHD, autism, and schizophrenia, calculated (using discovery effect size estimates and threshold of P < .05) from the largest available genome-wide association studies.Main Outcomes and Measures: Self-reported pregnancy-related measures capturing lifestyle behaviors, metabolism, infectious and autoimmune diseases, other physical health conditions, and medication use.Results: Data were available for up to 14 539 mothers (mean [SD] age, 30.00 [4.45] years) and 14 897 fathers (mean [SD] age, 32.46 [5.13] years) of European ancestry. Modest but robust associations were observed between specific pregnancy-related measures and maternal PGS, including ADHD PGS with asthma (odds ratio [OR], 1.15 [95% CI, 1.06-1.25]), smoking (OR, 1.26 [95% CI, 1.19-1.33]), prepregnancy body mass index (β, 0.25 [95% CI, 0.18-0.31]), pregnancy weight gain (β, 0.20 [95% CI, 0.10-0.30]), taking folate (OR, 0.92 [95% CI, 0.88-0.96]), and not taking supplements (OR, 1.09 [95% CI, 1.04-1.14]). Schizophrenia PGS was associated with coffee consumption (OR, 1.09 [95% CI, 1.05-1.12]), smoking (OR, 1.12 [95% CI, 1.06-1.19]), prepregnancy body mass index (β, -0.18 [95% CI, -0.25 to -0.11]), and pregnancy weight gain (β, 0.17 [95% CI, 0.07-0.27]). All 3 PGSs associated with symptoms of depression/anxiety (ADHD: OR, 1.15 [95% CI, 1.09-1.22]; autism: OR, 1.13 [95% CI, 1.06-1.19]; schizophrenia: OR, 1.13 [95% CI, 1.07-1.20]). Associations were largely consistent for maternal and paternal PGS, except ADHD PGS and smoking (fathers: OR, 1.13 [95% CI, 1.09-1.17]).Conclusions and Relevance: In this study, genetic liability to neurodevelopmental conditions that is passed from mothers to children was associated with several pregnancy-related factors and may therefore confound associations between these pregnancy-related factors and offspring neurodevelopment that have previously been thought to be causal. It is crucial that future study designs account for genetic confounding to obtain valid causal inferences so that accurate advice can be given to pregnant individuals. [ABSTRACT FROM AUTHOR]

Objective Fatigue and depression are highly comorbid phenotypes with partially overlapping symptoms. The main aims of the present study are to: (i) identify the risk of current fatigue and depression; (ii) determine if the depression symptoms experienced by individuals who are fatigued ( N = 766) and non-fatigued ( N = 1849) are different; and (iii) identify if the fatigue symptoms experienced by depressed ( N = 275) and non-depressed ( N = 2340) individuals are different, in a community-based sample of Australian twins aged over 50 years. Methods Fatigue and depression symptom profiles and classifications were generated using the Schedule of Fatigue and Anergia (SOFA); the General Health Questionnaire; and the Delusions-Symptoms-States Inventory, States of Anxiety and Depression questionnaires. The association between co-occurring fatigue and depression was assessed using prevalence ratios. Differences in the preponderance of fatigue and depression symptoms were assessed using logistic regression modeling. Results Individuals with either fatigue or depression have an approximately two-fold increased risk for comorbid presentation of both traits, compared to the general population. Logistic regression analysis indicated that fatigued individuals were significantly more likely to report all of the Diagnostic and Statistical Manual of Mental Disorders (DSM) depression symptoms assessed in the study. Similarly, depressed individuals were significantly more likely to report all SOFA fatigue symptoms. Conclusions Fatigue and depression are highly correlated traits within the community. Depression symptomatology and prevalence are significantly increased in fatigued individuals. Fatigue and especially the symptoms of insomnia and poor concentration are strong predictors of depression. Notably, the association between fatigue and depression is independent of their overlapping symptomatology. Therefore, presentation with fatigue, and in particular the symptoms of insomnia and poor concentration, should be considered as warning signs of depression in older adults. [ABSTRACT FROM AUTHOR]