Objectives: The goal of this paper is to present the methods that will be used in the initiation of the Finnish Prenatal Study of Autism and Autism Spectrum Disorders (FIPS-A). The purpose of FIPS-A is to examine the relationship between developmental factors associated with ASD from the 10th week of pregnancy to the age of 6 years in a population-based cohort by capitalizing on the Finnish Maternity Cohort (FMC), which consists of all births in Finland, as well as national, centralized comprehensive registries containing data on medical diagnoses, pregnancy, perinatal and neonatal complications.
Methods: A nested case-control design using the FMC is being used to evaluate the relationship between prenatal serologic factors, mediating and moderating developmental antecedents, and risk of ASD. The sampling frame consists of all offspring born in
Results: Total of 5036 cases of ASD were identified from the Finnish Hospital Discharge Register (FHDR) using diagnostic criteria from International Statistical Classification of Diseases, 10th Revision (ICD-10). The FHDR includes both hospital admissions and outpatient care. All cases were matched with four controls from the Medical Birth Register (MBR) on date of birth, sex and birth place. Prenatal serum samples are obtained from each pregnancy, and the archived sera will be analyzed for biomarkers of potential environmental risk factors. Mediating relationships of these factors with other pre-/perinatal and neonatal events and effect modification by sex and other risk factors will also be examined. Additionally, the relationship between serologically documented prenatal factors and anthropometric measures, documented prior to the onset of autism, will be examined.
Conclusions: The FIPS-A capitalizes on several important features: a national birth cohort, a large sample size, archived prenatal sera, virtually complete case ascertainment and comprehensive national registries. Many of the potential etiologies being investigated are risk factors that are modifiable by public health measures, and are relatively common in the population. These approaches include: vaccination to prevent influenza, improved hygiene to reduce exposure to toxoplasma, thyroid supplementation to correct deficiency of this hormone, and measures to reduce cigarette use during pregnancy to diminish fetal exposure to nicotine. These studies of prenatal etiologies, and their relationship to pregnancy and birth complications, offer the promise to develop a fuller understanding of uncovering pathogenic mechanisms by which these exposures alter fetal brain development and lead to autism.