Wednesday, January 12, 2011

Autism and Interpregnancy Interval

A paper came out earlier this week: Closely Spaced Pregnancies are Associated with Increased Odds of Autism in California Sibling Births.

In short, the researchers matched every single sibling birth in California from 1992-2002 with reports of getting services for autism, spent a good deal of time on the statistics and did a secondary case-controlled study to make sure they weren't missing anything.  And turns out that the odds of a second child born within 12 months of a first child (*actually I messed this up a little - it is an interpregnancy interval of less than 12 months - so a second child born less than 18 months after the first.  sorry!) have a little more than a 3 fold risk of having autism than a second child born more than 3 years after the first one.  Risk for second children born at interpregnancy intervals of between 12 and 36 months were middling, but risk rose abruptly between 12-18 and "0"-12 months.

Unfortunately, the researchers spent so much time in the paper reviewing the statistics and making sure every last variable was accounted for that the discussion as to why was about one paragraph.  They thought it might be folate depletion, omega 3 depletion, or stress (it is, obviously, very stressful to have a young baby and to be pregnant at the same time.)  In a number of posts on autism I have speculated as to some nutritional and genetic causes:

Diet and Autism1
Diet and Autism 2
Autism and Vitamin D
Autism 4 - Inflammation Speculation
Brain Efficiency, Pediatric Edition

Since, during pregnancy, a baby will tend to suck whatever nutrients are needed straight from mama, whether she can spare them or not, it would make sense that a nutritional explanation could account for the increased risk of autism in second children when the pregnancies are closely spaced. 

Here is a free, online, up to date, and comprehensive review of pregnancy, nutrition, and birth outcomes - if you are interested.

My ultimate preventative solution is, of course, to make sure that moms-to-be out there are consuming nutrient rich diets with plenty of folate, phospholipids, minerals, omega 3s, etc. etc. etc.

Also, it is snowing.  A lot.

Mailbox and Snow Bank



  1. Interesting. I've wondered about this, specifically in relation to my brother's birth a year after mine. He was a difficult kid, he has dyslexia, had behavioral issues (very oppositional), and looking back physical symptoms of omega 3 deficiency.

  2. Exacerbating the likely nutritional input to this is the pressure (self-imposed or otherwise) for mums to return to their pre-baby weight ASAP post-partum. This will often see all the usual dietary restriction we normally see - a high grain, low fat approach.

    The bottom line is that there WILL be some sort of fallout when a mother delays child-bearing for 15-25 years beyond biological capability, potentially spending much of that time boozing, dieting, under & over-exercising, stressing, OCPing, SSRIing, Prilosecing, and then trying to pop out 2.4 children in quick succession.

  3. @Jamie - in the study, the effect of birth order was amelioriated in pregnancies among the very young (age 20 or so) AND the very old (>35) - maybe us Advanced Maternal Age-ers are taking care to soak up the fish oil and folate before we conceive (I know I did).

  4. I think there is a bit more focus at a health care level on older mums to be. Over 35-40, there is probably more of a degree of planning, and perhaps better access to health care, pre-check ups, advice, supplementation, etc, by virtue of more financial stability.

    @Julianne - we had a discussion about this in the office a couple of days back. Without exception, all of us can think of examples of families with 3 siblings fitting this bill (being on a continuum of behavioural and health issues).

    7 years between myself and my headcase sister, with me conceived by a mother and father who, in 1973 London, hadn't heard of low fat anything! Phew!

  5. Emily,

    AWESOME post. I only wish I could have read it (and got it) 12 yrs ago! Every mother for pre-conception counseling should be forced to review it since the rate of autism is now ~1:100 and probably exponentially on the rise.

    Additionally all moms should have a good TSH < 1.0 (and FT4 FT3 in upper quartile ranges) and optiumum mineral, mag, vitamin D/A/E/K2 nutritional levels... (non-measurable of course).

    In terms of vision (n-3 and vit A) I have the best vision (no glasses except 'computer' D*MN IT) whereas my 3 siblings are all nearly legally blind or officially legally blind. Yeah. Like Jamie, I believe maximal vertical transmission went to me because I was the first born and only 1-2 yrs separated my 2 little sisters and I.

    Your beautiful, angelic children are SOOOO LUCKY for an intelligent, well prepared mom!!


  6. Great post but rather demoralizing as my youngest (now 18) is high functioning on the spectrum. Started to write a long comment, but will spare you here and inflict it on my own readers...:)

    In a nutshell, tho, I think the close spacing problem may be because it is probably older parents who are doing it and older fathers produce more autistic kids (over 35 is older for fathers in this case), and anyone who starts a family over 30 or 35 knows their fertility is waning and they'd better get a move on if they hope to have more than just one or two kids. In addition, one may (as we did) we so worried about the prospect of birth defects but unwilling to abort, so have an extra incentive to have children close together. Tragic if the attempt to increase the odds of having healthier children might lead to more of them having developmental disorders.

    The other argument for having kids young is that if you have an autistic one, you will be around for more of their life to watch out for them.

  7. Retriever - the paper is excrutiating to read for someone like me who is not all that interested in stats simply because they went through such effort to make sure that everything was taken into account. Families with a first child with autism were excluded from the analysis, for example, and age stratification of the results were done to make sure it wasn't age of mother or age of father contributing.

  8. Dr BG - I'm the second child, but born 3.75 years after the first. I like to think I'm in good health, however :) My girls are 22 months apart, and though I wasn't paleo, I did make sure to eat "real" food (meant lots of whole grains, though), get rid of vegetable oil, the vitamin had 1000 IU vit D in it anyway, and I made everything with butter or olive oil, had 1% milk instead of skim (sigh) in my oatmeal (sigh). They are both very healthy (knock on wood).

  9. Dr. Catherine Shanahan with her husband wrote a fascinating book Deeper Nutrition
    ( and in it she tells about what she calls Second Sibling Syndrome, which describes how the less nourished baby (two years or closer behind the first born) can have characteristics show in their facial features. She goes on to say that the population as a whole are all starting to become this way as nurition in general is worse in everyone.

  10. Yet another reason to breast feed... nature's way of putting space between babies!

  11. It's too bad about the poodle at your mailbox. I hope he wasn't yours. Perhaps it belonged to Rorschach.

  12. That's interesting. My son has autism and I was an undiagnosed Celiac and Crohnie at the time of his birth, so I think nutrition , or lack of, had it's role. Also, my brother is autistic and my mother is a suspected aspie who dicovered her migraines and stuttering were caused by gluten. So there's the nutrition and genes. Families also share gut flora and they are finding abnormal gut flora in these kids, so I think that's another biggie. Being born cesarean ups your odds ofhaving Celiacs and having autism.


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