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So, any experts want to comment on this paper?

Premature babies are more likely to be less intelligent, do worse at school and end up in lower-paid jobs than those born at full term, new research shows.

An analysis of the circumstances of more than 15,000 British adults also found that those born prematurely are much more likely to become unemployed, be less wealthy and not own a house.

The findings, from research led by Prof Dieter Wolke of Warwick university, are significant because they show that people being born prematurely are more likely to suffer financial as well as health consequences.

Wolke and his colleagues looked in detail at how two cohorts of children born between 28 and 42 weeks in 1958 and 1970 fared in adulthood. In both groups, premature babies had usually accumulated fewer qualifications and less wealth by the age of 42 than full-term peers.

My obvious thought was that premature birth is associated with lower socio-economic status anyway. But equally obviously, the paper must have corrected for that, right?

And yet I can’t help worrying about some of this medical research that discusses socio-economic status. Because quite famously the Marmot Report din’t make the obvious point. Yes, low socio-economic status can indeed cause health problems. But equally, health problems can cause low socio-economic status. And yet there wasn’t even an admission of the latter in that report.

So, anyone want to have a look at this paper and see if they’v taken into account the known correlation between prematurity and socio-economic status?

15 thoughts on “So, any experts want to comment on this paper?”

  1. You can download a copy of the paper here:

    A cursory reading suggests they did correct for parental education and social class. These were the most important covariate. The R2 values were not stellar I have to say. Also no correction was made for alcohol or drug abuse – so we don’t know if some of the effects were down to mums being stoned or permanently drunk and hence having preterm births with subsequent developmental deficits in the kids.

    Take home from all of this – if you’re going to be born pre-term then make sure it’s to a stable, educated and middle class family. And then make sure you do well at school – because that too seems to make a difference. It”s hardly rocket science is it…

  2. Cause / correlation fallacy spotting should be taught in schools.

    A favourite from our NCT classes: ‘mothers who smile during child birth reported lower levels of pain’.

  3. And of course, the care of premature babies today is better than it was several decades ago, so the results are of historical interest.

  4. They failed to differentiate between prems born early at appropriate size for gestation and small for dates babies whose normal development has been compromised in utero by various factors eg placental insufficiency, genetic, alcohol, rubella. Neonatal care improved substantially 1958-1970 and between then and now, reducing infant mortality but also allowing the survival of seriously ill children; some interventions eg ventilation raise the risks of intercranial bleeds and retinal damage in previously normal prems. But the paper kept academics from productive employment outside academia so I guess they’re happy.

  5. “Premature babies are more likely to be less intelligent, do worse at school”

    Anecdote is not data, but it was still amusing to read this on the very morning my son, 2 months premature and badly underweight, starts at grammar school.

    ProgContra’s suggestion seems a likely one to pursue – I think I’ve seen other studies that high levels of alcohol and drug use correlate with premature birth, and it would not be surprising that they correlate with poor performance at school (although I don’t know whether the numbers of babies born to addicts would be sufficient to create a correlation across the whole population). So the connection may be indirect rather than causal.

  6. “The following variables were considered as potential confounders based on previous studies…: sex, multiple birth status, birth weight standardised per week of gestation and sex…, maternal smoking during pregnancy, maternal diabetes, lack of antenatal care…, high … or low … maternal BMI before pregnancy (only available in NCDS), maternal age at birth, parity, parental education…and paternal social class…”

    “All pathways were adjusted for sex, multiple birth, birth weight standardised per week of gestation and sex, maternal smoking during pregnancy, maternal diabetes, lack of antenatal care, maternal age at birth, parity, parental education beyond minimum school leaving age and paternal social class.”

  7. From what I’ve read babies born sufficiently prematurely as to require an incubator are prone to all sorts of problems such that one might reasonably ask if it would have been better to just let nature take its course.

  8. Richard: The number of premature babies born to alcoholics may well be a serious chunk of all premature births even if all births to alcoholics do not form a big chunk of all births. So wouldn’t surprise me if that would make a difference when taken into account.

  9. To be fair to the authors, this is a pretty good study, and they do outline what the strengths and weaknesses of their analysis is and how future studies can improve upon it. It doesn’t make outrageous claims beyond what the analysis shows, and the results confirm the question that Tim asked, it is definitely strongly linked to socio-economic status. There is some insight in there for parents and teachers of pre-term children: They are statistically more likely than full-term children to struggle at maths, and that is a strong predictor for future wealth. They correctly point out also that maths ability is a predictor for wealth in all children. In other words, if you are a parent of a pre-term child, do make every effort to develop their maths ability, and make sure their teacher knows it is a priority. If you are a teaching organisation, it should be a key question to ask parents when their child enters. I, for one, didn’t know this before the study, and I would hazard that not many parents or teachers do either. I consider that valuable.

  10. “Premature babies are more likely to be less intelligent”: if you were being intellectually serious you’d therefore want a measure of the parents’ intelligence too. Parental education and paternal social class (paternal!) are pretty rough proxies; the real thing would be better.

    “Anecdote is not data”: we wouldn’t mind if the anecdote were actually interesting.

  11. Anecdote. One confounding factor might be school year. Let me explain. My son was born ten weeks premature weighing just 816 grams, on the 28th August. So just about the last day to be the youngest in his school year. In other words he is in the wrong year, he ought to be in a lower year, but try arguing that against the Great British School admittance bureaucrat.

    It’s a sort of double whammy. You’re young for your age anyhow, and you’re thrown into a class where even if that weren’t the case, you’re the youngest.

    A proportion of these pre-term babies will also face the same issue, have they accounted for this?

    BTW my son is still small for his age, but has no other problems, and shows academic promise; when he can be torn away from his Xbox. At least in these early years parental support is pretty much all, in my experience. Social class.

  12. @Ian Reid

    Not sure I’m following. If your son was born a few days later, he’d have been the oldest in his year – but surely position in the school year should have an equal effect on those born on or after 42 weeks?

    Might make a slight difference, but I can’t see any reason why we’d expect premature babies to be born at the end of August (unless you’re suggesting that children should be assigned to school years based on some standard of development level instead of age – which might well make sense, but would be a PITA and guaranteed to be wrong if done by govt).

  13. @Rational Anarchist
    What I’m saying is that there will be a proportion of pre-term babies who will be in a school year later than would be the case if they had been born at full term. Quite how large that proportion would be is difficult to say, it depends on the distribution of births throughout the year, and what exactly the definitions of pre-term for this study are. But if we assume that births are equally distributed throughout the year, and that in this study pre-term means those born tow months early, than all pre-term babies born in July and August, one sixth of the total, would be in a later school year than would otherwise be the case.

    There have been studies which show that the youngest in a class have less good outcomes than the rest of the class. It’s only epidemiology and there are all sorts of confounding factors, but if the same assumptions used in these studies have been made in this study, then this might explain some of the conclusions.

  14. Being a late August baby myself I would certainly agree about the issues involved in being almost a year younger than some of your class mates. There are some interesting studies on professional sports which show a bias towards children close to cutoff dates, basically the older kids have an edge which means they are selected for further development which increases the divide.
    Spending the first 5 years or so of my life in care I was lucky to be adopted into a middle class family and went from being behind at school to in the top 10% of my class academically throughout school. Not being written off and having the full time attention of a family makes a difference.

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