Studies - PreTerm Delivery / Premature Birth / Prematurity Complications

Prenatal and Perinatal Risk Factors for Autism (JPM, 1999)

Prenatal and Perinatal Risk Factors for Autism
Journal of Perinatal Medicine 27 (1999) 441-450
Larry Burd, Ph.D., Robin Severud, Jacob Kerbeshian, Marilyn Klug, University of North Dakota School of Medicine and Health Sciences…

[This is from a PDF of a 1999 study by Prof. Larry Burd which reported that women with prior IAs (Induced Abortions) triple their risk of a later newborn diagnosed with Autism. — Brent Rooney (MSc), Research Director, Reduce Preterm Risk Coalition,]


Aim: To identify pre- and perinatal risk factors for autism.

Method: Case control study. We matched names of patients from North Dakota who met DSM criteria for autism, a pervasive developmental disorder, and autistic disorder with their birth certificates. Five matched controls were selected for each case.

Results: Univariate analysis of the 78 cases and 390 controls identified seven risk factors. Logistic modeling to control for confounding produced a five variable model. The model parameters were X2 = 36.6 and p <0.001.

The five variables in the model were decreased birth weight, low maternal education, later start of prenatal care, and having a previous termination of pregnancy. Increasing father's age was associated with increased risk of autism.

Conclusion: This methodology may provide an inexpensive method for clinics and public health providers to identify risk factors and to identify maternal characteristics of patients with mental illness and developmental disorders.


In a case control study (univariate analysis) of 78 cases of autism and 390 matched controls we identified seven significant variables in this study which were: birth weight, apgar score at one and five minutes, mother's education, father's age, the trimester prenatal care started, and terminations of a prior pregnancy…

Having had a previous termination of pregnancy increased the risk of autism 236% compared to controls who did not have a termination of pregnancy….


Table IV. Logistic regression of significant variables from 78 cases of autism and five controls per case. The final two models consisted of four or five variables…
Variable                               Model 1                                  Model 2
                                   Coeff        O.R.                            Coeff                 O.R.

Other Terminations           1.213       3.36                           1.027                2.79

Month Prenatal Care Began   .261      1.30                            .258                1.29

Birth Weight                   .000483     1.00