A new study just came out in the International Journal of Epidemiology, called: “Post-term birth and the risk of behavioural and emotional problems in early childhood”. It was published online on May 3, 2012.
The press have widely reported that this study shows that when a pregnancy goes beyond 42 weeks, then a child is more than two times more likely to develop ADHD in early childhood.
You can find many media references to the study, and here is the link to a BBC article entitled: Overdue babies: ‘Risks for those born after 42 weeks’.
I am largely annoyed with the difference between what the study reports, and what the press are saying.
What The Study Reports:
First of all, this study is very interesting from the perspective that we often think about prematurity as a risk factor for ADHD, as well as other medical, learning and emotional issues. However, we don’t really think of a baby being ‘post dates’ as an issue for ADHD or other emotional or learning issues. The researchers point out that as a pregnancy goes beyond 40 weeks, the placenta may not be able to meet all of the needs of the baby, and thus going past dates may cause problems too.
This study followed the pregnancies of 5145 children in a large population-based prospective cohort study in Rotterdam, The Netherlands. Mothers enrolled between 2001 and 2005. Of the births, 382 (7%) were born post term. The researchers had all of the mothers complete the Child Behavior Checklist (CBCL) at the ages of 1.5 and 3 years old. This questionnaire has parents rate a wide range of symptoms in their children, and then the software calculates the scores, and provides a rating (based on parent report) on several different scales of emotional functioning – such as: anxiety, depression, somatic symptoms, ADHD, aggressive behavior, etc.
Please realize that questionnaires do not diagnose ADHD. Questionnaires can provide data, which can help an experienced clinician to conduct a more detailed assessment to see if ADHD (or any other condition) is actually there.
The research report says: “post-term born children had a higher risk for overall problem behaviour [odds ratio (OR)?=?2.10, 95% confidence interval (CI)?=?1.32–3.36] and were almost two and a half times as likely to have attention deficit / hyperactivity problem behaviour (OR?=?2.44, 95% CI?=?1.38–4.32).”
Let me highlight an important point there: “two and a half times as likely to have attention deficit / hyperactivity problem behaviour“. The questionnaire doesn’t diagnose ADHD, rather it points out that these children have more ‘ADHD problem behavior’ compared to babies born at term.
As an experience clinician and expert in ADHD, I know that it can be very difficult to diagnose kids with ADHD at a young age. It certainly can be done at 3 years old, but I am very cautious about a diagnosis at that age, and I certainly put a lot more work into it than just having the parents fill out a questionnaire. Personally, I would find this information more reliable if the researchers were able to provide follow up at school age – i.e. at 6 years old. That would give us a better idea of how the child was doing (of course I do understand that there are big issues with funding, timing, etc., but I still would love to see data at 6 years old).
Furthermore, I am left wondering: “is the relationship between post-term birth and ‘ADHD problem behavior’ truly a causal relationship?”
In other words, if we accept that the behavior ratings at 3 years old are accurate (i.e. there are more ADHD problem behaviors), then do we know for sure that this was caused by post-term birth?
Maybe there was another variable at play here.
In a cohort of over 5000 women, approximately 4% of them would be expected to have ADHD. That works out to about 200 women. It would be much more likely for these women to have children with ADHD problem behaviors irrespective of when their child was born (premature, on time, or post-dates). And what if they were more likely to refuse intervention from the doctor, and wait for nature to take its course? Then we may believe that it is going ‘post dates’ that is causing ADHD type symptoms, when in fact, we are just screening out for moms who have ADHD symptoms. Now, I have no science to back this up, and I do not believe that the mothers were screened themselves for ADHD. So this is complete conjecture. But, I think it’s an interesting theory.
Before I get flaming comments here, I’m not suggesting that women who refuse induction of labor, or who want to let nature take its course all have ADHD. Far from it. I’m just putting forward a theory which may refute the theory that it is a causal relationship between post-dates birth and developing ADHD.
What The Media Is Reporting:
The media is reporting that kids born post-dates (i.e. after 42 weeks) are over 2 times as likely to have ADHD. I read one report which went so far as to suggest that mothers should consider having a C-section before 42 weeks to help to prevent ADHD (I can’t find the exact news report to link to here, but trust me, I read it).
As you can see based on what I wrote above, I believe that these claims are over-simplified. I am not convinced that post-term births increase the risk of ADHD. This study has opened my eyes to the possibility that post-term births may be a risk factor for ADHD, or possibly other learning or behavioral issues, but it is by no means conclusive research. It’s my opinion that the media are over-simplifying this, and it may create more backlash and stigma for ADHD patients and their moms (like the mother-in-law saying: “I told you you should have listened to the doctor and had an induction of your labor at 41 weeks. The fact that you waited too long caused my grandson’s ADHD…”).
What do you think? How do you respond to the research, and the media reporting of it?
Please share your thoughts and comments below.