Thursday, 22 February 2018

Pre-eclampsia increased the risk of ASD in offspring: meta-analysed

"The finding suggests a need for early screening for ASD [autism spectrum disorder] in offspring of women with pre-eclampsia."

That was the conclusion reached in the meta-analysis published by Berihun Assefa Dachew and colleagues [1] covering the literature on pre-clampsia and offspring risk of autism or ASD.

Pre-eclampsia refers to a condition/state typically occurring after about 20 weeks of pregnancy. It is characterised by a combination of symptoms including hypertension (raised blood pressure) and the presence of protein in the urine (proteinuria).

On the basis that pre-eclampsia has been mentioned as a *possible* risk factor for subsequent offspring autism diagnosis (see here), the authors set about meta-analysing the peer-reviewed research in this area covering the period up to the middle of March 2017. They eventually settled on 10 studies that suitably covered the topic; of which 5 were rated as 'good in methodological quality' and the rest, somewhere between fair and poor.

Results: most studies (7/10) reported a positive association between the presence of pre-eclampsia and offspring autism. Most studies included for meta-analysis had taken into account some potentially important confounding variables such as child gender, "maternal age and substance use during pregnancy." The overall enhanced risk of offspring autism - "pooled relative risk (RR)" - associated with intrauterine exposure to pre-eclampsia was 32% compared with non-exposed children. And with that, you can perhaps see why the authors make that call for preferential screening for autism in children exposed to pregnancy pre-eclampsia.

But one must also be a little careful with such results. Careful because studies were usually looking at one pregnancy variable and one offspring outcome. To quote the authors, studies typically "did not consistently adjust for important confounding factors such as maternal obesity, parity, gestational diabetes and infection during pregnancy" all of which have been mentioned with offspring autism risk in mind (see here and see here and see here and see here respectively). Lots of things go on during pregnancy (and indeed, before pregnancy) that *could* have a sizeable impact - alone or in combination with each other - on various offspring outcomes including risk of a diagnosis of autism.

Still the results are what they are. They invite further investigations in this area, including those relevant to the possible hows-and-whys of pre-eclampsia exposure potentially contributing to a developmental/behavioural diagnosis and what strategies might be useful to consider [2] more generally...

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[1] Dachew BA. et al. Pre-eclampsia and the risk of autism-spectrum disorder in offspring: meta-analysis. British Journal of Psychiatry. 2018. Jan 24.

[2] Nordqvist M. et al. Timing of probiotic milk consumption during pregnancy and effects on the incidence of preeclampsia and preterm delivery: a prospective observational cohort study in Norway. BMJ Open. 2018; 8: e018021.

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