Working when pregnant same as smoking!

[fishface2]

There's an article in the family section of the guardian mobile website today that reckons a study has shown that mothers who work after 8 months pregnant can do similar damage to their baby as smoking mums.

Aibu to be annoyed at another reason for working mothers to feel guilty?

Most women work late so they can spend more of their maternity leave with their baby.

And surely women have always worked up to the birth even if at home.

Perhaps not an Aibu but interested in your thoughts.

Sorry, can't link .

Since there isn't a test for "makes small babies" I am going to guess no. But that's not the point. When you survey thousands of people small individual differences like that get evened out.

The sample size is large enough (and they calculate the statistical significance) that the difference in birth weight between those who worked for longer and those who gave up work sooner was very very unlikely to be due to chance.

I assume there are many reasons as to why a baby is born a small weight.
Smoking, what the mother eats, the exercise she does, what she does ie sahm or wahm, her family history etc.........The findings cannot be based on working or not working mothers as all jobs are different and some sahm have lots of kids and activities.

I really cannot see why these 'findings' can bare any truth

What jumping says.

The danger is that some people might look at this and think, very simplistically, that working = bad for baby.

There are just so many layers. Someone with poor skills and qualifications is more likely to be working in a low paid menial job . They are less likely to have a choice about whether they start maternity leave earlier. They are also less likely to be aware of healthy lifestyle issues. They are more likely to smoke and eat rubbish food. These are simple statistics. There are many factors which contribute to the increased likelihood of low birthweight

I also don't like the way it implies low birthweight is the only consequence of smoking. A smoker is causing damage to the child before and after the birth in various ways- its not just about the birthweight of the child. It would be interesting to see some stats about the weight gain after birth anyway, as my hunch would be that statistically, smokers are less interested in nutrition, less likely to breastfeed, and more likely to have young children with obesity issues.

If babies of smokers, on average, are lighter than those of non-smokers, it is not so important if the baby is full-term, but could make a difference between survival and good health or otherwise if the baby is born prematurely. Likewise, if you work to past 36 weeks, you are past the critical stage with your pregnancy anyway, so it matters far less if your baby is half a pound lighter.

Having worked to 35 weeks with an awkward communte, I don't think I could have stood more than one more week though.

"There are lots of factors" does not mean that we can't measure an individual factor. You just have to design your experiment well and balance things out when doing the calculations. It's difficult, but doable if you have enough data points.

Being smaller birthweight isn't always worse - its isnt just a case of the bigger the better with babies, so while this study is showing an effect on birthweight, it doesn't necessarily mean that it is a bad effect.

Looking at the article they seem to have found a 230g average difference, it might have been interesting if they has set a cut-off for being of 'low birth weight' and seen what proportion of babies in each group fell into that catergory.

I had a growth scan at 35 weeks, was measuring small. Baby was small, predicted 6lb birthweight (although I know this is fine!). They suggested that my stressful job (teaching at a rough secondary school) might be a factor. I stopped working at 36 weeks. Growth scan at 37 weeks said 6.5lb, dd born at 38 weeks 7lb 3. I know growth scans are inaccurate but to me that's a significant difference!

It was taken into account insofar as they looked at 30,000 women diddl. It would be extraordinarily unlikely with a survey of that size that the women with "small" genes all happened to work late into pg whilst the women with "big" genes all happened to stop work early.

OTOH it's not so unlikely that the women who smoked/drank/ate crap/had demanding jobs/lived in polluted areas were also the ones who worked later into pg because they were too broke to take a proper pre-birth break, because those factors are not randomly distributed. You'd need to dig deeper to discover whether the working late is the true cause.

But after all this is hardly a new idea. If you went to your obstetrician and said "I work on my feet all day in a shop: is it OK for me to carry in working until 37 weeks?" then she'd probably say "Best not to".

I also don't like the way it implies low birthweight is the only consequence of smoking. A smoker is causing damage to the child before and after the birth in various ways- its not just about the birthweight of the child. It would be interesting to see some stats about the weight gain after birth anyway, as my hunch would be that statistically, smokers are less interested in nutrition, less likely to breastfeed, and more likely to have young children with obesity issues.

But then you are also factoring in class and the lifestyle choices that come with it, as middle-class women are less likely to smoke in the first place and more likely to give up when pregnant or even thinking about it. Fifty years ago you would have got very different statistics when women of all backgrounds smoked during pregancy.

Dilys I'd like to think that they accounted for those things when they did the calculations, but it depends on how much information they had about each of the women.

I worked till 38.5 weeks last time. I'm absolutely tiny and DS was just over 8 pounds. None of the doctors could believe it as my bump measured very small too. If this study is right, god only knows what monster I might have produced if I'd given up work earlier.

http://www.jstor.org/stable/info/10.1086/664831 link to the paper
summary:
Using large American and British survey data, this paper provides structural estimates of the production functions for birth weight and fetal growth. In addition to maternal smoking, we estimate the impact of when a mother stops work, which has not been considered in the literature. Mothers? work interruptions of up to 3 months before birth have a positive effect on birth outcomes, especially among British children. Parental behavior appears to respond to child idiosyncratic endowments in a way that suggests that parents have inequity aversion concerns. Evidence in favor of inequity aversion emerges also from the analysis of breast-feeding decisions.

or even www.jstor.org/stable/info/10.1086/664831

The study doesn't say that you will have a baby that massively expands if you give up work. It says that on average people who work til the very end will have a smaller baby than if they had given up work earlier.

Yes it is half a pound; so not the difference between petite and massive. Normally, the baby grows 8 ounces a week in the last 4 weeks, so the difference would be 2 ounces per week.

On a serious note, it is interesting as a study.

I think smoking has an effect on more than birthweight so I don't think there is a direct comparison with work. That's just an eye-grabbing headline.

But it does suggest that if you are working very hard, stressed, commuting etc in late pregnancy it may have more of a physical effect than I would have given it credit for.

Agree that the headline is just a cheap attention grabber, but the research appears reasonable enough- it's a big survey, so the trends are probably fairly accurate (and I say that as someone who is going on mat leave at 39 wks tomorrow, albeit I only work PT and in a sedentary, stress free job).

That's what headlines are there to do - grab your attention so you read the story. There are only a very few words available so you aren't going to get much subtlety.

Here is a link to a paper reported in the NYTimes. Finding : women who exercise in pregnancy have somewhat lower birthweight babies ? Conclusion : exercising in pregnancy is good for the baby (because heavier babies are less healthy).

well.blogs.nytimes.com/2010/04/05/execise-during-pregnancy-lowers-babys-weight/

The thing is, an average lower birthweight could be either a good or a bad thing, depending on how it's distributed.

Statstically speaking, on average, babies with middling birth weights do best, whereas babies with either low or high birthweights have somewhat more health problems. So "230gr lower average birthweight" could be good (if it's achieved by a reduction in the number of very heavy babies) or bad (if it's achieved by an increase in the number of very light babies).

I haven't looked at either paper but if they really have made the leap reduction in average birthweigth --> baby more or less healthy then it's an outrageous abuse of statistics.

Interesting stuff Kirsty. The difference could be that your NY Times data relates to recent US births, where obesity is a very prevalent problem, whereas the data in the working women study relates to a combination of older US births and more recent (Millennium) UK births - both of which will be less likely to have obesity problems - tipping the balance in favour of "higher birthweight = good".

However, you'd want to see the whole range of birthweights before you could see whether that was the right interpretation.

@DilysPrice. That's true, but I still suspect that the link is more likely that whoever is doing the interpreting (which may be either the journalist or the scientist - as I say, I haven't read the papers) has a preconceived idea that, for example, exercising should be "good", so data that is ambiguous (from a good/bad point of view - the hard statistics seem very precise) is interpreted that way.

I once read an article about a paper about breastfeeding, which had found that breastfed infants were, on average, harder work and cried more. The conclusion (and this was a direct quote from one of the scientist IIRC) was that breastfeeding infants had a "more honest" relationship with their carers. Now, I'm a big fan of breastfeeding, but in this case, it seems clear to me that had the results been the other way round the conclusion would not have been that formula fed infants had a more honest relationship with their carers, rather that formula feeding creates incipient behavioural problems. And it's not clear to me that your "Interpretation" section is really science if, before you get any results, you have already decided that whichever way round they come out your conclusion will be that this is an advantage of breastfeeding.

There's a bit in that quote that says particularly in British women it seems to affect birth weight. I'd love to know more about that.

Pure speculation, but is ti because women in Britain are likely to have a longer commute/less understanding employers or what? In the US there is very little mat. leave and working days are long BUT there tends to be more informal flexibility, e.g. even top exec.s can take the afternoon off to get to their kids' soccer game, so long as the work is done when needed. So maybe US women are able to 'ease out' of pregnancy a bit more? (It was def. the case when I did mat cover for someone, but I have an excellent employer).

Or is it that women in the UK who do work to the last moment are more likely to be in far more 'Mc xx Job' type industries and there are associated factors like education, housing, general health & nutrition etc, whereas the majority of US women would all work to the last moment so there's a broader spread of those factors.