Why Prior Abortions Raise Autism Risk

Brent Rooney, M.Sc.

In 1999, Professor Larry Burd and colleagues reported that women with prior induced abortions had a three times higher risk of delivering a newborn later diagnosed with autism.¹ In the 1960s, the U.S. autism rate for newborns was approximately 1 in 10,000, but the rate skyrocketed to 1 in 110 in 2009 according to the Centers for Disease Control.

Is it biologically plausible that prior maternal induced abortions elevate a newborn baby’s autism risk? In a word, yes. This is because of two mechanisms — preterm birth (very preterm and extremely preterm) and raised parental age at delivery. Six significant studies report that prior induced abortions boost extremely preterm birth risk (under 28 weeks’ gestation).

Extremely preterm babies have about 25 times the autism risk as do full-term (at least 37 weeks’ gestation) babies.² The older the parents are at delivery, the higher the autism risk. In a 2001 study of French women, Dr. Henriet reported that French women with more than one prior induced abortion had 2.4 times (i.e. 140% higher) the risk of maternal age over 34 at delivery compared to women with zero prior induced abortions.³

Michael Ganz estimates that the lifetime cost (medical costs + non-medical costs + reduced income) of a U.S. newborn with autism to be $3.2 million.⁴

Should abortion providers wait for “conclusive” proof of the abortion-autism risk before warning women of a possible increased autism risk? My understanding of U.S. law is that patients must be warned of a serious adverse risk of a treatment for which there is credible evidence (“credible” evidence is well short of so-called “conclusive” evidence). One hundred percent “conclusive” evidence in the field of medical research (in particular, epidemiology) for a purported risk factor does not and can not exist (in statistical jargon, the Gaussian distribution can never provide 100 percent confidence of higher risk or 100 percent confidence of lower risk).

For those who want to dig deeper into the subject of autism, read the 2010 book The Age of Autism (Olmsted & Blaxill). Certainly, the authors much suspect that mercury in vaccines is a likely cause of autism. I suspect that both oral contraceptives and prior induced abortions elevate autism risk; and more generally, that anything that undermines a young woman’s health raises her risk of delivering a newborn later diagnosed with autism.

Brent Rooney, M.Sc., is the Research Director at the Reduce Preterm Risk Coalition, based in Vancouver. This article originally appeared in Justice for Kids Now Bulletin, Feb. 28, 2011. Reprinted with permission.

Citations

1. Burd, L. Severud, R. Kerbeshian, J. Klug, MG. Prenatal and perinatal risk factors for autism. J Perinat Med. 1999; 27(6):441-50.

2. Limperopoulos C.  Autism spectrum disorders in survivors of extreme prematurity. Clin Perinatol 2009; 36:791-805.

3. Henriet L, Kaminski M. Impact of induced abortions on subsequent pregnancy outcome: the 1995 French national perinatal survey. BJOG 2001;108(10):1036-1042 [Study Population: French women]

4. Michael L. Ganz . The lifetime distribution of the incremental societal costs of autism. Archives Pediatric Adolescent Medicine 2007;161:343-349.