"Are women with autism at an increased risk of adverse pregnancy outcomes?"

The paper by Heléne Sundelin and colleagues [1] provides the blogging fodder today, and research pertinent to the question: "Are women with autism at an increased risk of adverse pregnancy outcomes?" The short answer to the question is yes: "Maternal autism is associated with preterm birth, likely due to an increased frequency of medically indicated preterm births, but also with other adverse pregnancy outcomes, suggesting a need for extra surveillance during prenatal care."

It was refreshing to read the results from Sundelin et al (a research group who are no strangers to autism research) because this was a study devoted to looking at women with autism / autistic women and their pregnancy outcomes. It was distinct from other research on maternal pregnancy outcomes and offspring autism more traditionally seen in the peer-reviewed research literature and covered on this blog (see here and see here for examples).

The source material for the Sundelin study was the Swedish Medical Birth Registry (yes, one of those fantastic Scandinavian population registries again) and records of "2,198 births to 1,382 women with autism and 877,742 births to 503,846 women never diagnosed with autism." When comparing the groups across various different measures including preterm delivery ("defined as <37 completed weeks of gestation"), tobacco smoking during pregnancy and the use of various prescription medicines during pregnancy, some interesting trends were observed.

"Women with autism were at an increased risk of preterm birth..., which after stratification, remained for moderately (32 to <37 weeks) preterm birth." Also: "Maternal autism was also linked with an increased risk of elective cesarean delivery in births to women with autism" and "Preeclampsia was more prevalent in mothers with autism."

Although not seemingly affecting many of the 'adverse' pregnancy outcomes examined, researchers also noted that rates of tobacco smoking (light and heavy use) during early pregnancy were elevated in mums with autism, alongside prescription medicine use (antiepileptics, antipsychotics, hypnotics/anxiolytics, antidepressants) being more frequently reported before and during pregnancy compared to non-autistic pregnant mums. Authors reported that "there was no increased risk of adverse pregnancy outcomes except for induction of delivery" but one has to remember that the focus was on pregnancy outcomes - "completed weeks of gestation, mode of delivery, 5-minute Apgar scores, intrauterine growth, stillbirth, and maternal complications (preeclampsia and gestational diabetes)" - and does not say anything about longer term post-pregnancy outcomes. I say this with a few potential 'issues' in mind (see here and see here and see here).

The Sundelin study is by no means perfect - a "limitation is the lack of information on life circumstances" - but does carry the research weight that comes from those extremely well-categorised Scandinavian population registries. The authors conclude that their: "results suggest a need for individual prenatal care for women with autism, weighing pros and cons for continuation of psychotropic medication, with a better understanding of the difficulties related to autism, especially regarding the communication with health care professionals." Who am I to argue with them?

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[1] Sundelin HE. et al. Pregnancy outcomes in women with autism: a nationwide population-based cohort study. Clin Epidemiol. 2018 Nov 30;10:1817-1826.

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Fatty acid supplementation and autism (again)

The findings reported by Sarah Keim and colleagues [1] (open-access available here) provide the discussion fodder today, on a topic that has graced this blog a few times: fatty acid supplementation in the context of autism (see here).

Indeed, it was coincidental that at the same time as the Keim findings appeared on PubMed, so I also stumbled upon news headlines suggesting that maternal use of fish oil supplements (i.e. fatty acids) *might* reduce offspring risk of allergies (see here). This is also an interesting finding; particularly in light of some observations that, appearing alongside the presence of certain childhood allergies, risk(s) of certain neurodevelopmental disorders might be heightened (see here and see here). I might just be adding 2 and 2 together and coming up with 5, but it strikes me that there could be some potentially important connections to be further explored between fish oils, allergy and offspring behavioural diagnoses...

Anyhow, detailing some quite small-scale results - N=31 children "aged 18–38 mo born at ≤29 wk of gestation" - garnered as part of something called The Preemie Tots Trial, Keim et al observed results that "suggested improvements in core ASD [autism spectrum disorder] symptoms as measured by the BITSEA ASD [Brief Infant Toddler Social and Emotional Assessment] scale." I might add that other data from this trial has, I think, already seen the peer-reviewed science publication light of day [2] and on more than one occasion [3].

The actual aim of the Keim study was to "confirm the feasibility of a full-scale trial in toddlers born very preterm and exhibiting ASD symptoms." This is probably why the participant numbers were quite small on this occasion, and why the autism-related findings don't yet need to be trumpeted out loud too much.

To accomplish their research goals, authors conducted a 90-day trial employing the gold-standard research method - "randomized, fully blinded, placebo-controlled trial" - where preterm born children received either "Omega-3-6-9 Junior (Nordic Naturals, Inc.) treatment (including 338 mg eicosapentaenoic acid, 225 mg DHA, and 83 mg GLA)" or a placebo: "canola oil (124 mg palmitic acid, 39 mg stearic acid, 513 mg linoleic acid, 225 mg α-linolenic acid, and 1346 mg oleic acid)".

Outside of the results obtained suggesting some potential positive effect(s) for the fatty acid supplement on autistic signs and symptoms, researchers also confirmed that within the confines of their study period: "No safety concerns were noted." Given that such fatty acid supplements are widespread in their availability, and often sold as a food supplement rather than a preparation with some medicinal claims, I probably wouldn't have expected anything else. That being said, I have heard isolated reports of some children taking fatty acid supplements and things not necessarily being wholly positive in terms of behaviour, bearing in mind anecdote is not the singular of data. This might however also tally with other data reporting no effect from fatty acid supplementation in some instances of autism (see here).

I understand that there is more to come from Keim and colleagues now that this pilot data has been published. I'd like to think if the results are confirmed and some biochemistry added to the mix (i.e. measuring functional fatty acid levels before and after supplementation), this intervention approach could be rolled out much further, as well as things like potential best-responders (and non-responders) being more accurately identified...

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[1] Keim SA. et al. ω-3 and ω-6 Fatty Acid Supplementation May Reduce Autism Symptoms Based on Parent Report in Preterm Toddlers. J Nutr. 2018 Feb 1;148(2):227-235.

[2] Boone KM. et al. Omega-3 and -6 fatty acid supplementation and sensory processing in toddlers with ASD symptomology born preterm: A randomized controlled trial. Early Hum Dev. 2017 Dec;115:64-70.

[3] Sheppard KW. et al. Effect of Omega-3 and -6 Supplementation on Language in Preterm Toddlers Exhibiting Autism Spectrum Disorder Symptoms. J Autism Dev Disord. 2017 Nov;47(11):3358-3369.

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Neonatal hyperbilirubinemia and autism risk (again)

Tall ships @ Paul Whiteley

The paper by Luis Lozada and colleagues [1] (open-access) brings back into focus a topic that has graced this blog before (see here) with their observation that: "Children who develop ASD [autism spectrum disorder] are more likely to have an admission with a diagnosis of jaundice in the neonatal period and more likely to require treatment for this jaundice."

Jaundice, by the way, refers to a condition marked by yellowing of the skin and eyes as a result of the build up of a compound called bilirubin. For the newborn, elevations in bilirubin can have some really negative effects when accumulating in parts of the brain.

Using a case-control study design based on data derived from the "TRICARE Management Activity’s Military Health System (MHS) database", authors set about assessing whether there was a heightened risk of autism (ASD) "among infants with a history of neonatal unconjugated hyperbilirubinemia (jaundice)." Participant numbers were in the thousands: "A total of 2917 children with ASD and 8751 matched controls were included in the study."

Using two definitions of jaundice and hence bilirubin exposure - "a diagnosis of jaundice during the hospital stay associated with birth, or during an admission within the first month of life" and/or "any phototherapy or exchange transfusion procedure in the first month of life" - authors reported that: "A history of admission with a diagnosis of neonatal jaundice was present in 640 (21.9%) of children with ASD compared with 1614 (18.4%) of controls." Further: "A procedural treatment for jaundice was documented in 107 (3.7%) of children with ASD and 221 (2.5%) of controls." On the basis of these figures and some statistical analysis, they concluded that there may be an association between bilirubin and autism (ASD). That being said, such an association was not uncomplicated. When for example, they undertook a separate analysis of those children who were born preterm - that is born before 37 weeks - the association between autism and jaundice lost its statistical significance.

These data are interesting and mirror other findings (see here) with equally large participant numbers. As the authors indicate, there are some important methodological strengths to their study that add to quality of the study findings. The one down side to the study however was the fact that the authors "did not have bilirubin levels available", so any efforts looking at "a specific dose–response relationship with ASD" are research fodder for another day.

Insofar as the possible mechanism of effect going from neonatal jaundice to autism risk, the neurotoxin angle to bilirubin is a preferred explanation for Lozada et al. As they note: "There is biologic plausibility to suggest an association between bilirubin and ASD" in terms of parts of the brain vulnerable to bilirubin toxicity and what has been identified in the large (very large) peer-reviewed literature talking about brain architecture and [some] autism. Mention is also made about the concept of BIND (bilirubin-induced neurologic dysfunction) and the possibility of an overlap with some of the core and peripheral signs and symptoms of autism.

Accepting that any link between bilirubin and autism is likely to be a complex process, the only thing I would perhaps add to speculations would be the possible intersection with the concepts of sulphation and glucuronidation - important metabolic mechanisms that have been suggested to be disrupted in some cases of autism (see here and see here respectively). I would be interested to see whether any underlying issues with such metabolic pathways might intersect with jaundice and the metabolism of bilirubin and onwards autism risk...

Music: Blackbird - The Beatles.

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[1] Lozada LE. et al. Association of Autism Spectrum Disorders With Neonatal Hyperbilirubinemia. Global Pediatric Health. 2015; 2: 2333794X15596518.

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Lozada, L., Nylund, C., Gorman, G., Hisle-Gorman, E., Erdie-Lalena, C., & Kuehn, D. (2015). Association of Autism Spectrum Disorders With Neonatal Hyperbilirubinemia Global Pediatric Health, 2 DOI: 10.1177/2333794X15596518

Screening for autism in preterm infants

"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 [1] 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 [2] (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 [3] 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.

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[1] 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.

[2] 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.

[3] 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.

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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

Late/moderately preterm kids at risk for a positive autism screen

If you're sick of the sight of tinsel and/or turkey (delete as appropriate), I promise no more mention of them in this post. Just a brief introduction to the the paper by Alexa Guy and colleagues [1] (open-access) who concluded that: "LMPT [late and moderately preterm] infants are at significantly increased risk for positive autistic screen."

Megamind, incredibly handsome criminal
genius and master of all villainy!

Based on the [final] analysis of data from some 600 LMPT infant and 760 term-born infants taking part in a study initiative here in the UK, researchers looked at M-CHAT (Modified Checklist for Autism in Toddlers) scores derived from parental questioning when the child was 2 years old. They found: "LMPT infants were at significantly increased risk for a positive M-CHAT questionnaire screen compared with term-born infants, and this remained significant after application of the follow-up interview and exclusion of infants with neurosensory impairments." Further that their findings: "provide empirical evidence that screening for ASD is especially confounded in preterm populations" as a function of the the high false-positive rate found compared against the term-born controls.

M-CHAT has cropped up a few times on this blog (see here for example). In recent times, the schedule has undergone a bit of (further) revision, evolving into the M-CHAT-R/F [2] (see here for further details) to further improve on its sensitivity statistics when it comes to assessing risk of an autism spectrum disorder (ASD). Indeed, as per the Guy quote: "An M-CHAT follow-up interview is essential as screening for autism spectrum disorders is especially confounded in preterm populations" one can perhaps see where M-CHAT R/F might be particularly handy for further study of this important group.

These results add to an already sizeable volume of peer-reviewed research literature hinting that the timing of our very earliest introduction into the world might influence risk of neurodevelopmental issues such as autism and/or a positive screen for potential autism. That being said, the various factors linked to time in-utero such as birth weight as potentially impacting on development illustrate how complex an issue this might be. How we screen for autism in among the various complexities of preterm births (and lower birth weight) remains a question on many people's minds, including the possibility of using more than one instrument [3].

Music to close: Norwegian Wood.

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[1] 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.

[2] 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.

[3] Dudova I. et al. Comparison of three screening tests for autism in preterm children with birth weights less than 1,500 grams. Neuropsychiatr Dis Treat. 2014 Nov 17;10:2201-2208.

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Guy, A., Seaton, S., Boyle, E., Draper, E., Field, D., Manktelow, B., Marlow, N., Smith, L., & Johnson, S. (2014). Infants Born Late/Moderately Preterm Are at Increased Risk for a Positive Autism Screen at 2 Years of Age The Journal of Pediatrics DOI: 10.1016/j.jpeds.2014.10.053

Term vs. preterm birth and the presentation of autism

The paper by Katherine Bowers and colleagues [1] continues the interest in the concept of 'the autisms' with their observations on the presentation of autism (and its comorbidities) when looking at those "born preterm versus those born at term".

We'd better get back, 'cause it'll be dark soon,
and they mostly come at night... mostly

Based on an analysis of quite a healthy participant number heading up to 900 "males and females with autism spectrum disorder", authors reported on several phenotypic differences between the 13% born preterm compared to the majority born following a full-term pregnancy. These differences, also influenced by gender, were in core areas such as language skills and the presence of comorbidities such as sleep apnea and attention-deficit hyperactivity disorder (ADHD). The authors conclude that their results "may have implications for understanding the underpinnings of a subset of individuals with autism spectrum disorder and contribute to the development of focused treatments for autism spectrum disorder among children born preterm".

Whilst one should always be a little cautious about making too much of any specific link with something like preterm birth (see here to illustrate the many and varied outcomes following this variable) I was interested in the Bowers' results. I think back to similar research into autism subgroups from Unwin and colleagues [2] (talked about in a previous post) describing how low birth weight was "associated with greater sleep disturbances".

Although many variables can affect foetal growth measures, preterm birth can adversely impact on birth weight and with that, one might see a possible common feature appearing in relation to issues at birth. That being said, the strength of any association between preterm birth and something like the comorbid presence of ADHD in cases of autism is likely to be a complex issue as per the findings from Harris and colleagues [3] who concluded that in the general population: "former late preterm infants have similar rates of LD [learning disabilities] and ADHD as term infants".

Bowers et al also took into account a role for gender in their results, reporting that there may be more to see here. Although quite an obvious variable to look at when it comes to autism (see here), there is perhaps not as much appreciation of how sex might link into autism phenotypes as one might imagine. Recently, Reinhardt and colleagues [4] did venture into this area, concluding that whilst they did not see any "significant effects of sex or a diagnostic group by sex interaction" when it came to autism presentation, further research is indicated in this area. I might add that such investigations might also wish to look further at comorbidity too, or autism plus [5] if you like.

Music to close and Bulletproof by La Roux.

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[1] Bowers K. et al. Phenotypic differences in individuals with autism spectrum disorder born preterm and at term gestation. Autism. 2014 Sep 5. pii: 1362361314547366.

[2] Unwin LM. et al. A "bottom-up" approach to aetiological research in autism spectrum disorders. Front Hum Neurosci. 2013 Sep 19;7:606.

[3] Harris MN. et al. ADHD and learning disabilities in former late preterm infants: a population-based birth cohort. Pediatrics. 2013 Sep;132(3):e630-6.

[4] Reinhardt VP. et al. Examination of Sex Differences in a Large Sample of Young Children with Autism Spectrum Disorder and Typical Development. J Autism Dev Disord. 2014 Sep 5.

[5] Gillberg C. & Fernell E. Autism Plus Versus Autism Pure. J Autism Dev Disord. 2014 Jun 24.

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Bowers K, Wink LK, Pottenger A, McDougle CJ, & Erickson C (2014). Phenotypic differences in individuals with autism spectrum disorder born preterm and at term gestation. Autism : the international journal of research and practice PMID: 25192860

Neonatal jaundice and increased risk of ADHD

The findings from Chang-Ching Wei and colleagues [1] suggesting an over-representation of the diagnosis of attention-deficit hyperactivity disorder (ADHD) following a history of neonatal jaundice provides fodder for today's brief post. Based in Taiwan, one of the most impressive countries when it comes to the use and analysis of 'big data' (see here), researchers were able to identify some 25,000 participants diagnosed with neonatal jaundice and compare them with almost 70,000 non-jaundiced controls to calculate: "the incidence rate and hazard ratios (HRs) of physician-diagnosed ADHD".

"Imperial troops have entered the base"

They observed that the "incidence of ADHD was 2.48-fold greater in the jaundice cohort than in the nonjaundice cohort (3.84 vs. 1.51 per 100,000 person-years) in the study period" between 2000 and 2008. Several other variables also seemed to affect the HR of ADHD including being male, being born preterm and being a low birth weight infant. To my mind, finding such variables already potentially connected to a heightened risk for a diagnosis of ADHD [2] strengthens the Wei results when it comes to jaundice potentially also being a risk factor. The authors conclude: "A risk alert regarding neurologic consequences is urgently required after a neonatal jaundice diagnosis" bearing in mind the need for further research on the potential mechanisms at work in this proposed relationship.

I'm becoming pretty interested in the cognitive and developmental outcomes associated with cases of neonatal jaundice. As per previous posts on this blog on jaundice and autism (see here and more recently here), there are definitely grounds for quite a bit more investigation in this area. The overlap between something like ADHD with autism (at least some of the autisms) also begs the question whether there may be some tie up between the various diagnoses and something like neonatal jaundice. It certainly wouldn't be the first time that ADHD and autism have been mentioned with the same risk factors in mind as for example, with the increasingly interesting area of asthma and childhood neurodevelopmental issues (see here and see here)...

Music to finish. I assume most people have heard the very sad news about actor and comedian Robin Williams this morning. Just the other day I was introducing my brood to Mork and Mindy... RIP.

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[1] Wei CC. et al. Neonatal jaundice and increased risk of attention-deficit hyperactivity disorder: a population-based cohort study. J Child Psychol Psychiatry. 2014 Jul 24.

[2] Chu SM. et al. The relationship between attention deficit hyperactivity disorder and premature infants in Taiwanese: a case control study. BMC Psychiatry. 2012 Jul 23;12:85.

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Wei CC, Chang CH, Lin CL, Chang SN, Li TC, & Kao CH (2014). Neonatal jaundice and increased risk of attention-deficit hyperactivity disorder: a population-based cohort study. Journal of child psychology and psychiatry, and allied disciplines PMID: 25056274

Gestational age at delivery and special educational need

An article by Boyle and colleagues* (full-text) published in the BMJ provided some food for thought recently with the conclusion that even babies born at what would be considered term (37-38 weeks) may suffer from poorer health than those born at 39 - 41 weeks. To me this seems like a very narrow window when it comes to something like birth timing and future health outcomes bearing in mind what risk means and the myriad of potential confounding variables.

Autism is not specifically mentioned in the Boyle article but nevertheless there is some opinion on a possible relationship between gestational time and associated risk. Indeed, I don't know about you but to me it seems like almost every week a new study is published suggesting that adverse conditions at birth might place a person at elevated risk of developing an autism spectrum condition. OK perhaps I over-exaggerate with the 'every week' bit but certainly this is a recurring theme. As if to prove a point take a look at this paper recently published by Movsas and Paneth** on gestational age and symptom severity in autism.

There are other examples suggesting that low birth weight increases the risk, breech presentation, planned caesarean section, hyperbilirubinema... the list goes on. Indeed so numerous are the factors, studies and accompanying media reports that I very often don't even read them in their entirety anymore given the wealth of evidence that is being built up around our entrance into the world.

On the one hand, in a world full of questions about autism - its aetiologies (plural) and natures - such reports have contributed to a valuable area of research with regards to risk and also potentially mechanisms pertinent/contributory to at least some cases. With a condition which has by far raised more questions than science has currently answered, these kinds of 'pointers' might turn out to be important ones.

On the other hand, there does seem to be a tendency to present this relationship slightly out of context; in that autism receives all the attention in relation to something like premature/pre-term babies yet at the expense of a much larger relationship between something like birth dates and special educational needs (SEN) as a whole.

To illustrate this point, my attention turned to quite a powerful study published a few years back by MacKay and colleagues** (full-text) which looked at the rate of SEN based on population registry data where detailed birth data was also present. I should at this point describe a few details about how things worked.

The study was conducted in Scotland which, at the moment, is still part of the United Kingdom (UK). For those unfamiliar with UK healthcare system, we have the National Health Service (NHS) which is paid for through direct taxation and currently means that all citizens, irrespective of income or status, have a right to free healthcare at the point of need. From cradle to grave, each person has a unique NHS number, which alongside some quite copious amounts of note-taking, provides an impressive bank of health information about a person. Health services often overlap with other areas such as social and educational services (most of the time) which can form quite a detailed picture of a citizen as evidence by the Child Health Profiles reports for example which are accessible to all and provide a wealth of information. Having experienced first-hand how much information is gathered at birth and the early years, I can vouch for this being a pretty good system.

In addition, I quote from the study: "Under the Special Educational Needs and Disability Act of 2001, both schools and local education authorities in the United Kingdom have a statutory duty to identify, assess, and make provision for children with SEN". SEN covers quite a lot of diagnostic ground including learning disability, autism spectrum conditions, ADHD, dyslexia and dyspraxia.

So with these details in mind, the study:

• Based on a large school-aged population covering 19 Scottish local authority areas, details of 514,188 children above 4 years and below 19 years of age were included for study.
• School census data showing SEN status was linked to the Scottish Morbidity Record (SM2) via birth certificate data.
• Complete data was available for 362,688 children of whom 17,784 (4.9%) had a record of SEN.
• In amongst the large amount of results obtained, a few key points were noted including: low birth weight (<2500 g) was associated with an increased risk of subsequent SEN (unadjusted odds ratio [OR] 2.22). This finding was linked to the primary finding that preterm delivery also correlated with risk of SEN, with extreme prematurity (24-27 weeks) carrying the greatest risk (OR = 6.92) steadily declining as children were born closer to their due date but then increasing for infants born overtime after their due date (42 weeks).
• Importantly, whilst preterm births (<37 weeks) increased the risk of SEN, only a relatively small proportion of SEN was linked to prematurity (5.3%) compared with SEN with a history of 39 weeks gestation (1.7%). 
• As per the description of SEN, autism as a diagnosis is included. Having said that, no specific data is provided on the distribution of particular diagnoses in the presented dataset so we can't readily ascertain any specific relationship between autism diagnoses and preterm birth from the current paper.

If you have a bit of time free and are interested in this kind of study, I would encourage you to have a look through the MacKay article in its entirety. For me, the important point to take from this study is that autism, some cases of autism, may very well be linked to preterm birth and onward to factors such as birth weight but such a relationship does not appear to be exclusive to autism and might not necessarily take into account other SEN diagnoses working as comorbidities. Perhaps a smaller detail is that with the current lack of a national autism register here in the UK, SEN status with a focus on autism might be a rough-and-ready way to provide a figure on autism rates at least in the UK pediatric population?

To finish, my car journeys are currently filled with the sound of the Beautiful South and the line - She's a PhD in “I told you so,” you've a knighthood in “I'm not listening” as featured in the song Don't marry her (the clean version).

* Boyle EM. et al. Effects of gestational age at birth on health outcomes at 3 and 5 years of age: population based cohort study. BMJ. March 2012
DOI: 10.1136/bmj.e896

** Movsas TZ. & Paneth N. The effect of gestational age on symptom severity in children with autism spectrum disorder. JADD. March 2012.

*** MacKay DF. et al. Gestational Age at Delivery and Special Educational Need: Retrospective Cohort Study of 407,503 Schoolchildren. PLoS ONE. 2010; 7: e1000289.
DOI: 10.1371/journal.pmed.1000289