"A positive screen on the M-CHAT [Modified Checklist for Autism in Toddlers] occurs more commonly in very preterm infants than those born at term."
So said the study by Peter Gray and colleagues  as the topic of preterm status - that is, babies born alive before 37 weeks of pregnancy - potentially being linked to a greater risk of autism or at least, increased risk of screening positive for autism, crops up yet again on this blog (see here).
Gray et al examined a cohort of children born at the very boundaries of the definition of preterm ("≤30weeks gestation") when aged 2 years old, questioning mums of preterm children (n=97) and mums of term infants (n=77) with a whole range of questionnaires / schedules including the M-CHAT and the Child Behaviour Checklist (CBCL) among other things. "Previously collected data from the mothers at 12months - the Edinburgh Postnatal Depression Scales (EPDS)" were also analysed.
Authors reported that a higher percentage of preterm kids "screened positive on the M-CHAT" compared with term controls (13.4% vs. 3.9% respectively). These statistics decreased somewhat as a consequence of "an M-CHAT follow-up interview by phone" with only one child with membership of the preterm group subsequently receiving a diagnosis of autism from the entire cohort. The authors discuss some of the whys and wherefores of those pretermers who initially screened positive on the M-CHAT and how they were: "born to younger, non-Caucasian mothers and were of lower birth weight and had a higher incidence of being small for gestational age."
As per my discussion on the paper by Alexa Guy and colleagues  (see here again), the message coming through about using M-CHAT with the preterm population is again one of 'use with caution'. Indeed, the Gray paper illustrates how the follow-up consultation is a pretty important part of M-CHAT, something further developed on by the findings from Diana Robins and colleagues  and the whole M-CHAT-R/F thing (see here). I wouldn't necessarily say that M-CHAT is completely useless as a screen for autism under certain conditions. Merely that looking for the early red flags that might denote autism is very much still a work in progress potentially confounded by length of gestation. YouTube video anyone?
Music: PJ Harvey- The Words That Maketh Murder.
 Gray PH. et al. Screening for autism spectrum disorder in very preterm infants during early childhood. Early Hum Dev. 2015 Mar 9;91(4):271-276.
 Guy A. et al. Infants Born Late/Moderately Preterm Are at Increased Risk for a Positive
Autism Screen at 2 Years of Age. J Pediatrics. 2014. 5 December.
 Robins DL. et al. Validation of the modified checklist for Autism in toddlers, revised with follow-up (M-CHAT-R/F). Pediatrics. 2014 Jan;133(1):37-45.
Gray PH, Edwards DM, O'Callaghan MJ, & Gibbons K (2015). Screening for autism spectrum disorder in very preterm infants during early childhood. Early human development, 91 (4), 271-276 PMID: 25766314