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I've previously talked about factors during pregnancy and parturition (child birth) in relation to autism as per posts like this one from quite a while back and all that newer stuff from initiatives like CHARGE. Combined with investigations examining everything from season of birth to birth weight to birth order, there is quite a bit of peer-reviewed literature on this area with autism in mind.
Having said all that, I don't want to give any false impression that there are any hard and fast rules about in-utero or birth factors being linked to autism, because there aren't. Indeed, it's all even further complicated by lots of other conditions potentially being linked also to pregnancy and birth and a flurry of speculation.
Nevertheless, there are some interesting points raised by each of the articles presented today which are worthy of discussion. So in turn:
The Langridge paper:
- Open-access so please do have a look at it for yourself. A huge data mining study examining the "total population data sets of children diagnosed with ID and ASD in Western Australia (WA)" between 1984 and 1999 (included among N=383,153) to see if there were any links between "maternal conditions and perinatal factors for all WA children subsequently diagnosed with ASD, with or without ID, and children with varying severity of ID, and compare findings to the rest of the birth cohort of unaffected children". Lots of description of the population and how autism and intellectual disability (ID) were ascertained. Also how this huge dataset were analysed.
- Results: yes, quite a few depending on how the data were modelled and what background characteristics were controlled for. Notably suggesting that those diagnosed with an ID were more likely to have experienced some episode or event in their earliest days when compared with those diagnosed with an ASD. I'll leave you to pick out the associations but there were some interesting findings related to gestational diabetes, threatened abortion before 20 weeks and pregnancy hypertension.
- Soundbite: "small head circumference was associated with reduced risk of ASD" bearing in mind head size and autism is a complicated area.
- Another soundbite: "These findings support the concept that ID and ASD may lie on a continuum, as opposed to being different clinical entities, and may explain why there are various ID subtypes of ASD (i.e. ASD with and without ID)". I can't fault their logic. Perhaps another addition to the spectral model of behaviour and psychiatry since that is the direction things seem to be heading these days.
The Lehti paper examined IVF (In vitro fertilisation) and...
- A very organised paper which bluntly asked: "Does IVF increase the risk of autism spectrum disorders (ASDs)?"
- Another very big participant group (autism: n=4164, matched controls: n=16,582); all born in Finland.
- Result: "This study showed no increased risk of ASDs in children born after IVF" as per other studies in this general area.
- But... and it is a but, the connection in particular between IVF and boys with Asperger syndrome (AS) might need to be looked at with greater assiduity. Having said that, any study had better be done sooner rather than later since AS as an independent diagnostic entity is due to be phased into ASD in the latest DSM revision in May (2013). Please note: this does not mean that people will lose their AS diagnosis though.
Combined, these papers add quite a bit to the literature on birth factors in relation to autism bearing in mind risk is risk and not proof. Although events in-utero and during childbirth have always been on the autism research radar, I am noting a renewed interest in all things early development with autism in mind in recent years as per areas like maternal immune activation and autism risk (think Paul Patterson and mice) and some continued interest in the environment (think pollution and correlation for a start). The suggestion that the placenta for example may play a "potent role in autism risk" represents quite an exciting research opportunity, mirroring research on other health-related conditions. Thin-fat body anyone?
* Langridge A. et al. Maternal conditions and perinatal characteristics associated with autism spectrum disorder and intellectual disability. PLoS ONE. 2013; 8: e50963.
** Lehti V. et al. Autism spectrum disorders in IVF children: a national case-control study in Finland. Hum Reprod. 2013 Jan 4.
Amanda T. Langridge, Emma J. Glasson, Natasha Nassar, Peter Jacoby, Craig Pennell, Ronald Hagan, Jenny Bourke, Helen Leonard, & Fiona J. Stanley (2013). Maternal Conditions and Perinatal Characteristics Associated with Autism Spectrum Disorder and Intellectual Disability PLoS ONE : 10.1371/journal.pone.0050963