An Ultrasound Study of Fetal Biometrics in Relation to Maternal Autistic Traits.

Background: The prenatal period is a critical time for brain development. During this period of early development, the unborn child has the potential to be negatively influenced by factors such as maternal infections and teratogens. Such epigenetic factors in the intrauterine environment have been linked to the development of many neurodevelopmental outcomes, including Autism Spectrum Conditions (ASC). Research has shown that autistic traits are partly heritable. Therefore, we predict mothers’ scores on the Autism Spectrum Quotient (AQ) will influence fetal growth development. To date, only a handful of studies have observed prenatal development in relation to ASC. All studies have observed this potential marker of abnormal development retrospectively, either from measures taken at the time of birth or using growth measures from medical ultrasounds at 12 and 20 weeks.

Objectives: This study observed longitudinal fetal growth measures taken at 12-, 20- and between 26-30 weeks of pregnancy to observe the potential influence of material autistic traits on fetal development.

Methods: The sample comprises of 130 singleton pregnancies with no immediate family with an ASC diagnosis. Prenatal ultrasounds were procured from medical records at 12- and 20-weeks, and an additional ultrasound between 26-30 weeks pregnancy. 2D and 3D scans were performed using a GE 8 Expert Ultrasound system. Mothers were asked to complete an AQ at the time of their 3^rd scan. Fetal head circumference (HC), abdominal circumference (AC), femur length (FL) and ventricular atrium (VA) measures were taken at each time point and standardised according to UK fetal biometry reference charts. Using partial correlations, the standardised growth measures and the discrepancies between them were compared across maternal AQ scores. This was carried out separately for each gestation and growth parameter.

Results: There was no significant correlation between fetal growth (HC, AC, FL or ventricular atrium) and mothers’ AQ score even when controlling for gender and gestational age.

Conclusions: These preliminary findings suggest that there is no association between fetal physical development and mothers’ AQ scores. This supports previous retrospective findings suggesting there are no differences in fetal biometry in children diagnosed with ASC. However, all pregnancies included in the study were low risk for ASC due to a lack of a diagnosis in the immediate family. The absence of any significant relationship here could reflect the narrow range of AQ scores, of the effects of parental traits on child development could be subtler, and are more likely to be evident in child behaviour later in development. Previous research has implicated a relationship between HC and brain size, suggesting the inference of fetal brain growth from HC. However, this is yet to be tested. This study will further explore brain development in relationship to HC during fetal growth and will follow these infants’ development until they are 18-months old to observe subsequent physical and behavioural development.