The Association of Intrapair Birth-Weight Differences With Internalizing and Externalizing Behavior Problems

Perinatal and neonatal factors and mental disorders in children and adolescents: looking for the contributions of the early environment to common and dissociable aspects of psychopathology

High rates of co-occurrence of mental disorders have been hypothesized to represent a result of common susceptibility to overall psychopathology. The purpose of this study is to test the hypothesis that commonalities among psychiatric disorders might be partially driven by sharable perinatal and neonatal environmental factors for mental disorders. Participants were 6-14 years of age children and their parents. Primary caregivers provided data on perinatal and neonatal information assessed retrospectively (n = 2231). Psychiatric disorders diagnoses were assessed using the Development and Well Being Behavior Assessment (DAWBA). We used bifactor models to disentangle common from dissociable aspects of psychopathology. These models allow modeling psychiatric disorders as the result of a common domain of psychopathology (p-factor) and three dissociable domains (fear, distress, and externalizing symptoms). Associations were tested using linear and tobit regression models. The p-factor was associated with male sex, low socioeconomic status, gestational smoking, gestational drinking, low levels of maternal education and presence of mental disorder in the mother. Associations with specific factors also emerged suggesting some risk factors might also have some role for fear, distress and externalizing factors. Our study supports the hypothesis that overall susceptibility to psychopathology might be partially driven by sharable perinatal and neonatal factors.

Evaluation of Birth Weight and Neurodevelopmental Conditions Among Monozygotic and Dizygotic Twins

Importance

Low birth weight is associated with an increased likelihood of neurodivergence and neurodevelopmental conditions (NDCs) such as autism, attention-deficit/hyperactivity disorder (ADHD), and intellectual disability. However, it is unclear whether birth weight contributes independently to NDCs or whether the association is predominantly driven by genetic predisposition.

Objective

To estimate the associations between birth weight and dimensional (trait) and categorical (diagnoses) NDC outcomes, while adjusting for genetic risks.

Design, Setting, and Participants

A co-twin design was applied to this case-control study conducted in Sweden. Diagnostic assessments were conducted between August 2011 and March 2022, within the Roots of Autism and ADHD Twin Study in Sweden (RATSS) during a 2.5-day participant visit to the clinic. The RATSS sample comprised phenotyped monozygotic and dizygotic twins enriched for NDCs. Data analysis was conducted in November 2022.

Exposure

Birth weight.

Main Outcomes and Measures

Categorical and dimensional operationalizations of autism, ADHD, and intellectual disability were assessed. Generalized estimating equation models were fitted across and within twin pairs.

Results

The study sample included 393 twins: 230 were monozygotic and 159 were dizygotic (zygosity was unknown for 4). Their median age was 15 (range, 8-37) years. There were 185 female participants (47.1%) and 208 male participants (52.9%). Across twin pairs, higher birth weight was associated with fewer autistic traits (unstandardized β [B], -5.51 [95% CI, -10.09 to -0.94]) and lower odds of autism diagnosis (OR, 0.63 [95% CI, 0.45 to 0.88]) and intellectual disability (OR, 0.42 [95% CI, 0.19 to 0.92]). Within pairs, the association between birth weight and dimensional autism (B, -17.35 [95% CI, -28.66 to -6.04]) and categorical autism (OR, 0.02 [95% CI, 0.001 to 0.42]) remained among monozygotic pairs but not dizygotic pairs. In addition, higher birth weight was associated with lower odds of ADHD diagnosis (OR, 0.003 [95% CI, 0 to 0.70]), fewer ADHD traits (B, -0.25 [95% CI, -0.39 to -0.11]), and higher IQ ratings (B, 7.43 [95% CI, 1.05 to 13.82]) among monozygotic twins.

Conclusions and Relevance

The findings of this co-twin study suggest an association between low birth weight and NDCs, but they also acknowledge the importance of genetics because the associations observed were only statically significant among monozygotic twins. It is of pivotal importance to facilitate early identification of factors contributing to fetal growth restriction to minimize detrimental outcomes.

Birth weight rather than birth length is associated with childhood behavioural problems in a Czech ELSPAC cohort

Many physical and psychological characteristics are influenced by prenatal development. Some studies have located links between low birth parameters and behavioural problems, with the latter in turn associated with educational progress, career success, overall health, and subsequent life events. However, few studies have investigated whether this association also applies to children in the normal birth growth range. This study thus investigates the relationship between normal-range birth length, weight, and behavioural problems at the age of seven. We use data from the Czech part of the European Longitudinal Study of Pregnancy and Childhood (ELSPAC) cohort, which provides comprehensive insight into a post-communist country undergoing a period of economic transition. Childhood behavioural problems were measured in 1,796 children using the Strengths and Difficulties Questionnaire. Associations were modelled using weighted logistic regression. Birth weight was found to be linked to the total difficulties score, hyperactivity, and peer relationship problems subscales in a fully adjusted model while birth length was not significantly associated with any subscale in the fully adjusted model. We thus conclude that normal-range birth weight is associated with behavioural problems. It can therefore be assumed that the odds of behavioural problems and their consequences can be mitigated by preventive programs targeting pregnant women and children with lower but still normal weight.

Gender-specific effect of pregnancy-related anxiety on preschooler's emotional and behavioral development: A population-based cohort study

BACKGROUND

Pregnancy-related anxiety plays a major role in shaping offspring's neural development. However, its gender-specific effect on children's emotional and behavioral development is controversial and the knowledge of critical period is limited. This study aims to examine gender-specific effect of pregnancy-related anxiety on preschooler's emotional and behavioral development.

METHODS

This study was based on the China-Anhui Birth Cohort Study (C-ABCS). A total of 3443 mother-child pairs were included in final data analysis. Pregnancy-related anxiety was assessed by Pregnancy-Related Anxiety Questionnaire respectively in the 1^st and 3^rd trimester of pregnancy. Strengths and Difficulties Questionnaires (SDQ) were completed by parents to assess preschool emotional and behavioral development in boys and girls. Logistic regression models were used to examine the association between pregnancy-related anxiety and preschoolers' emotional and behavioral problems.

RESULTS

The overall prevalence of pregnancy-related anxiety was 31.6%. Compared with those whose mothers without pregnancy-related anxiety in either 1^st or 3^rd trimester, preschool boys born of mothers with pregnancy-related anxiety in the 1^st trimester and in the 3^rd trimester had an increased risk of conduct problems. Pregnancy-related anxiety in the 1^st, 3^rd trimester and in both trimesters all related with preschool boys' hyperactivity and total difficult problems. Pregnancy-related anxiety in the 1^st trimester and in both 1^st and 3^rd trimester increased the risk of preschool girls' emotional problems and total difficult problems.

CONCLUSION

Pregnancy-related anxiety may relate with preschool boys' externalizing problems in early and late of pregnancy and increase the risk of internalizing problems in girls in early pregnancy.

LIMITATIONS

There was no data on pregnancy-related anxiety in the second trimester.

Birth weight is associated with adolescent brain development: A multimodal imaging study in monozygotic twins

Previous research has shown that the prenatal environment, commonly indexed by birth weight (BW), is a predictor of morphological brain development. We previously showed in monozygotic (MZ) twins associations between BW and brain morphology that were independent of genetics. In the present study, we employed a longitudinal MZ twin design to investigate whether variations in prenatal environment (as indexed by discordance in BW) are associated with resting‐state functional connectivity (rs‐FC) and with structural connectivity. We focused on the limbic and default mode networks (DMNs), which are key regions for emotion regulation and internally generated thoughts, respectively. One hundred and six healthy adolescent MZ twins (53 pairs; 42% male pairs) followed longitudinally from birth underwent a magnetic resonance imaging session at age 15. Graph theoretical analysis was applied to rs‐FC measures. TrackVis was used to determine track count as an indicator of structural connectivity strength. Lower BW twins had less efficient limbic network connectivity as compared to their higher BW co‐twin, driven by differences in the efficiency of the right hippocampus and right amygdala. Lower BW male twins had fewer tracks connecting the right hippocampus and right amygdala as compared to their higher BW male co‐twin. There were no associations between BW and the DMN. These findings highlight the possible role of unique prenatal environmental influences in the later development of efficient spontaneous limbic network connections within healthy individuals, irrespective of DNA sequence or shared environment.

Early environmental risk factors for neurodevelopmental disorders - a systematic review of twin and sibling studies

While neurodevelopmental disorders (NDDs) are highly heritable, several environmental risk factors have also been suggested. However, the role of familial confounding is unclear. To shed more light on this, we reviewed the evidence from twin and sibling studies. A systematic review was performed on case control and cohort studies including a twin or sibling within-pair comparison of neurodevelopmental outcomes, with environmental exposures until the sixth birthday. From 7,315 screened abstracts, 140 eligible articles were identified. After adjustment for familial confounding advanced paternal age, low birth weight, birth defects, and perinatal hypoxia and respiratory stress were associated with autism spectrum disorder (ASD), and low birth weight, gestational age and family income were associated with attention-deficit/hyperactivity disorder (ADHD), categorically and dimensionally. Several previously suspected factors, including pregnancy-related factors, were deemed due to familial confounding. Most studies were conducted in North America and Scandinavia, pointing to a global research bias. Moreover, most studies focused on ASD and ADHD. This genetically informed review showed evidence for a range of environmental factors of potential casual significance in NDDs, but also points to a critical need of more genetically informed studies of good quality in the quest of the environmental causes of NDDs.

The effect of birth weight on behavioral problems in early adolescence: New evidence from monozygotic twins

It is well-established that the prenatal period is a critical and sensitive period of an individual's life, linking prenatal circumstances to short- and long-term outcomes such as infant mortality, educational and occupational success. However, little is known about how prenatal nurture affects intermediate outcomes and noncognitive characteristics such as behavior and behavioral problems. In this paper, I investigate the effects of birth weight on behavioral problems at age 12. I comprehensively control for confounders related to family background and genetics by employing a research design exploiting differences among Danish monozygotic twins. I find that birth weight has a statistically significant negative effect on behavioral problems measured using the Strengths and Difficulties Questionnaire, and that birth weight affects boys and girls differently: birth weight is significantly negatively associated with emotional problems among girls and hyperactivity among boys.

Association between birth weight and educational attainment: an individual-based pooled analysis of nine twin cohorts

BACKGROUND

There is evidence that birth weight is positively associated with education, but it remains unclear whether this association is explained by familial environmental factors, genetic factors or the intrauterine environment. We analysed the association between birth weight and educational years within twin pairs, which controls for genetic factors and the environment shared between co-twins.

METHODS

The data were derived from nine twin cohorts in eight countries including 6116 complete twin pairs. The association between birth weight and educational attainment was analysed both between individuals and within pairs using linear regression analyses.

RESULTS

In between-individual analyses, birth weight was not associated with educational years. Within-pairs analyses revealed positive but modest associations for some sex, zygosity and birth year groups. The greatest association was found in dizygotic (DZ) men (0.65 educational years/kg birth weight, p=0.006); smaller effects of 0.3 educational years/kg birth weight were found within monozygotic (MZ) twins of both sexes and opposite-sex DZ twins. The magnitude of the associations differed by birth year in MZ women and opposite-sex DZ twins, showing a positive association in the 1915-1959 birth cohort but no association in the 1960-1984 birth cohort.

CONCLUSION

Although associations are weak and somewhat inconsistent, our results suggest that intrauterine environment may play a role when explaining the association between birth weight and educational attainment.