Psychological stress during pregnancy is known to have a range of long-lasting negative consequences on the development and health of offspring. Here, we tested whether a measure of prenatal early-life stress was associated with a biomarker of physiological development at birth, namely epigenetic gestational age, using foetal cord-blood DNA-methylation data. Longitudinal cohorts from the Netherlands (Generation R Study [Generation R], n = 1,396), the UK (British Avon Longitudinal Study of Parents and Children [ALSPAC], n = 642), and Norway (Mother, Father and Child Cohort Study [MoBa], n1 = 1,212 and n2 = 678) provided data on prenatal maternal stress and genome-wide DNA methylation from cord blood and were meta-analysed (pooled n = 3,928). Measures of epigenetic age acceleration were calculated using three different gestational epigenetic clocks: “Bohlin”, “EPIC overlap” and “Knight”. Prenatal stress exposure, examined as an overall cumulative score, was not significantly associated with epigenetically-estimated gestational age acceleration or deceleration in any of the clocks, based on the results of the pooled meta-analysis or those of the individual cohorts. No significant associations were identified with specific domains of prenatal stress exposure, including negative life events, contextual (socio-economic) stressors, parental risks (e.g., maternal psychopathology) and interpersonal risks (e.g., family conflict). Further, no significant associations were identified when analyses were stratified by sex. Overall, we find little support that prenatal psychosocial stress is associated with variation in epigenetic age at birth within the general paediatric population.

Background. Autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and schizophrenia (SCZ) are highly heritable and linked to disruptions in foetal (neuro)development. While epigenetic processes are considered an important underlying pathway between genetic susceptibility and neurodevelopmental conditions, it is unclear (i) whether genetic susceptibility to these conditions is associated with epigenetic patterns, specifically DNA methylation (DNAm), already at birth; (ii) to what extent DNAm patterns are unique or shared across conditions, and (iii) whether these neonatal DNAm patterns can be leveraged to enhance genetic prediction of (neuro)developmental outcomes. Methods. We conducted epigenome-wide meta-analyses of genetic susceptibility to ASD, ADHD, and schizophrenia, quantified using polygenic scores (PGSs) on cord blood DNAm, using four population-based cohorts (npooled=5,802), all North European. Heterogeneity statistics were used to estimate DNAm pattern overlap between PGSs. Subsequently, DNAm-based measures of PGSs were built in a target sample, and used as predictors to test incremental variance explained over PGS in 130 (neuro)developmental outcomes spanning birth to 14 years. Outcomes. Probe-level analyses showed SCZ-PGS associated with neonatal DNAm at 246 loci (p<9x10-8), predominantly in the major histocompatibility complex. Functional characterization of SCZ-PGS loci confirmed strong genetic effects, significant blood-brain concordance and enrichment for immune-related pathways. 8 loci were identified for ASD-PGS (mapping to FDFT1 and MFHAS1), and none for ADHD-PGS. Regional analyses indicated a large number of differentially methylated regions for all PGSs (SCZ-PGS: 157, ASD-PGS: 130, ADHD-PGS: 166). DNAm signals are largely unique for individual PGSs. Finally, a DNAm-based measure of genetic susceptibility at birth nominally increased explained variance for several child cognitive and motor outcomes above PGS, but not after multiple testing correction. Interpretation. Genetic susceptibility for neurodevelopmental conditions, particularly schizophrenia, is detectable in cord blood DNAm at birth in a population-based sample, with largely distinct DNAm patterns between PGSs. These findings support the early-origins perspective on schizophrenia. Funding. HorizonEurope; European Research Council Keywords. Population-based; Genetic susceptibility; DNA methylation; Epigenetics; Neurodevelopmental conditions; Generation R Study; PREDO; ALSPAC; MoBa

The goal of this prospective longitudinal study was to explore whether co-occurrent internalizing difficulties and aggression in early childhood convey increased risk for later mental health problems in middle childhood. Participants were mothers from the Norwegian Mother, Father and Child Cohort Study (MoBa), who provided assessments of child internalizing difficulties and aggression at ages 3 years (n = 54,644; 26,750 girls) and 5 years (n = 38,177; 18,794 girls), as measures of child depressive, anxiety, conduct-related, and oppositional defiant (OD) symptoms at age 8 years. Using latent profile analyses (LPA) of internalizing difficulties and aggression, four profiles were identified: low-symptom/normative; primarily internalizing; primarily aggressive; and co-occurrent. Among the other results, the co-occurrent group exhibited the highest levels of depressive, anxiety, and oppositional defiant symptoms at 8 years. Most children (78%) remained stable in their profile between ages 3 and 5 years. Among the transition patterns that emerged, transitions were observed both from the normative to a risk profile and vice versa. Children who remained stable within the co-occurrent profile or who transitioned from the co-occurrent profile to one of the other two risk profiles also exhibited more depressive, anxiety, and OD symptoms at 8 years of age, when compared with children who transitioned from the co-occurrent to the normative profile. The heterogeneity between early manifestation of internalizing difficulties and aggression, and specific type of later mental health symptoms not only supports a shared etiology between internalizing and externalizing difficulties but also points toward the need for person-centered monitoring in early childhood with further implications for early identification of difficulties and preventive measures.

Abstract STUDY QUESTION Do expectant parents experience increased anxiety and depression during pregnancies conceived through ART compared to spontaneous conception? SUMMARY ANSWER Among all expectant parents in the sample, those who conceived through ART reported overall lower levels of anxiety and depression in pregnancy compared to expectant parents who conceived spontaneously, while in the subsample of parents who conceived both through ART and spontaneous conception, expectant mothers experienced increased anxiety and depression in early pregnancy following ART compared to spontaneous conception. WHAT IS KNOWN ALREADY Previous research on expectant parents’ psychosocial adjustment in response to ART has found mixed results, with some studies suggesting ART is associated with increased anxiety and depression, and other studies suggesting improved mental health or no relationship. Mixed findings may relate to the use of cross-sectional designs that do not account for confounding differences between groups, or variability in the timing of assessment. STUDY DESIGN, SIZE, DURATION This prospective cohort study used data from the Norwegian Mother, Father and Child Cohort Study (MoBa), which includes 2960 pregnant women who underwent ART and 108 183 women who conceived spontaneously. Of these, a subsample of expectant parents had two consecutive pregnancies with one pregnancy resulting from ART and one conceived spontaneously (n = 286 women, n = 211 partners). Women self-reported their composite symptoms of anxiety and depression at two timepoints during each pregnancy (gestational weeks 17 and 30). Their partners self-reported composite symptoms of anxiety and depression at 17 weeks gestation during each pregnancy. Couples reported their relationship satisfaction at 17 weeks gestation. MAIN RESULTS AND THE ROLE OF CHANGE Using a conventional full-cohort analysis we found that ART was associated with less total anxiety and depression and greater relationship satisfaction, compared to spontaneous conception among both women and men. However, in the subsample of parents who experienced both ART and spontaneous pregnancies, ART was associated with increased levels of maternal anxiety and depression at gestational age 17 weeks (M = 1.19), compared to spontaneous pregnancies (M = 1.15), 95% CI of the mean difference 0.006, 0.074. At 30 weeks gestation, anxiety and depression were similar across both types of pregnancies. Expectant fathers reported similar levels of anxiety and depression at 17 weeks gestation during both pregnancies. Among women relationship satisfaction was higher following ART conception than spontaneous conception. LIMITATIONS, REASONS FOR CAUTION There is potential for selection effects in the sample, as women who have conceived through both ART and spontaneous conception in their first two pregnancies are rare. In addition, several factors that may be important predictors of mental health in this context, such as previous miscarriages and long-term infertility, were not assessed in the current study. WIDER IMPLICATIONS OF THE FINDINGS Our findings indicate that previous discrepancies in the literature may be related to inherent differences between the groups of parents receiving reproductive treatment and those who do not. This study addresses that limitation by prospectively comparing different types of pregnancies within the same expectant parents. Earlier inconsistencies may also relate to variations in gestational age when anxiety and depression were assessed. By examining symptoms at two timepoints in each pregnancy, we were able to examine the relation between gestational age and symptoms of anxiety and depression. STUDY FUNDING/COMPETING INTEREST(S) The MoBa is supported by the Norwegian Ministry of Health and the Norwegian Research Council/FUGE (grant number 151918/S10). This work was also supported by the Research Council of Norway grant number 288083 and 301004. The authors have no conflicts of interest to declare. TRIAL REGISTRATION NUMBER N/A.

Intelligence is a core construct of individual differences in cognitive abilities and a strong predictor of important life outcomes. Within recent years, rates of cesarean section have substantially increased globally, though little is known about its effect on neurodevelopmental trajectories. Thus, we aimed to investigate the influence of delivery by cesarean section on the genetics of intelligence in children.