Maternal Autistic Traits and Adverse Birth Outcomes

This cohort study assesses the association of maternal autistic traits with preterm birth and neonates born small for gestational age.

eMethods.Assessment of covariates eTable 1. Descriptive characteristics by level of maternal autistic traits eTable 2. Comparison of characteristics of women included the analysis with those excluded eTable 3. Association between maternal autistic traits and adverse birth outcomes, further adjusted for antenatal psychological distress (Model S1) and excluding women with a history of psychiatric conditions or who took psychotropic medication during pregnancy (Model S2) eFigure 1. Sample flow chart eFigure 2. Distribution of maternal autistic traits in the study sample This supplemental material has been provided by the authors to give readers additional information about their work.eMethod 1. Assessment of covariates 1) Assessment of antenatal psychological distress Antenatal psychological distress was assessed during the first trimester by using the Japanese version of the Kessler Psychological Distress Scale (K6+). 1 The K6+ is a validated six-item self-rated psychological distress questionnaire that measures symptoms of depression and anxiety over the last 30 days (range 0-24, higher scores indicate more severe distress). 2The scale is reported to predict mood or anxiety disorder according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV

) Assessment of pre-existing health conditions, pre-existing psychiatric conditions and psychotropic medication Information
on pre-existing physical and psychiatric conditions was obtained from maternal selfreports during pregnancy.The use of psychotropic medication during pregnancy was obtained by interviewing the mothers by Research Coordinators.

Descriptive characteristics by level of maternal autistic traits
Measured using the short form of the Autism Spectrum Quotient Japanese version (AQ-J10) administered during the second and third trimesters.The Clinical-range represents women who scored above the clinical cutoff of seven.b Measured using the Kessler Psychological Distress Scale (K6+) administered during the first trimester, available for 86414 women.

Comparison of characteristics of women included the analysis with those excluded a
P-values for group differences were obtained using t-tests for continuous variables and chi-squared tests for categorical variables.c Measured using the short form of Autism Spectrum Quotient Japanese version (AQ-J10) administered during the second and third trimesters.The Clinical-range represents women who scored above the clinical cutoff of seven.
a N varies due to missing values.b eTable 3.

Association between maternal autistic traits and adverse birth outcomes, further adjusted for antenatal psychological distress (Model S1) and excluding women with a history of psychiatric conditions or who took psychotropic medication during pregnancy (Model S2)
The results are presented for a 1 SD increase in maternal autistic traits.b Adjusted for maternal age at birth, maternal education level, primiparous status, pre-pregnancy maternal body mass index, smoking during pregnancy, pre-existing physical health condition, child sex, gestational hypertension, gestational diabetes mellitus, and antenatal psychological distress.c Antenatal psychological distress was measured using the Kessler Psychological Distress Scale (K6+) during the first trimester.d History of psychiatric conditions was measured based on self-report, and the use of psychotropic medication during pregnancy was obtained from maternal interviews by research coordinators (See eMethod2 for details).e Adjusted for maternal age at birth, maternal education level, primiparous status, pre-pregnancy maternal body mass index, smoking during pregnancy, pre-existing physical health condition, child sex, gestational hypertension, and gestational diabetes mellitus. a