Thursday, 8 April 2010

Weigh more! Weigh less! Think of the baby!!

Been on a bit of a break. Not away, just consumed by books (Robin Hobb again), stupid iPod games, spending time with family and sleeping.

But coming home from work tonight I heard a news interview on Checkpoint that has driven me back to blog.

It's Mary Wilson talking to a NZ paediatrician [audio] who has conducted some research that seems to show that women who do light exercise during pregnancy have babies with lower birth weights.

Now I'm confused. Lower birth weight is supposed to be one of the negative outcomes of smoking during pregnancy. But now lower birth weight is also a positive thing that can mean a child doesn't become obese, and later become an obese adult, who, if female, then becomes an obese pregnant woman, who then in turn gives birth to a heavier baby, which goes on to become... Obesity Epidemic WIN!

The paediatrician did say that the pregnant women didn't lose any weight as a result of the exercise, and that there were some positive outcomes for themselves as a result of their extra activity, so that's good. Nice to know it's not all about the fetus. But he did talk about how tired the women were before they got on the exercycle, and while the exercise alleviated that afterwards one of the standard pieces of medical advice about activity during pregnancy is if you are already tired you should stop and have a rest.

Yet again it seems you can't win. Exercise can be good for you and the fetus. Exercise can be bad for you and the fetus. A lower birth weight for the baby can be positive or negative, and should thus be enouraged/avoided.

Frankly I'll start listening to this stuff when they tell me I can eat feta while I'm pregnant. That's the kind of pregnancy advice I'm hanging out for!

16 comments:

Lucy said...

...no feta when pregnant?! Damn.

Julie said...

No feta or camembrie as soft cheeses can carry listeria which can kill fetuses. You can have it if it's piping hot though, but that's not the same as on crackers, or just eaten straight from the packet nom nom nom.

Anonymous said...

Perhaps lower birth weight being negative refers to lower than normal birth weight. Perhaps the paediatrician advocating exercise to reduce birth weight is referring to very overweight mothers who may have unhealthily overweight babies. Exercise for those mothers will improve their health and the health of their babies. And pregnancy may provide the motivation to start a healthier lifestyle which could last for life and therefore the children as they grow would be exposed to healthier food and exercise. Lower birth weight being both negative and positive seems entirely reasonable with the above two scenarios are considered.

Trouble said...

I interpreted the MoH advice with respect to feta as it's ok if you open up a fresh packet and eat it then and there, but not if you leave it in the fridge, opened, a couple of days. It made for some very bad housekeeping when I couldn't think of enough hot dishes to use up the opened feta (frittata is good).

It sounds like the story about birthweight is too subtle or complex to turn into useful advice. I exercised when it felt good and rested when I was tired - normal birthweight baby.

stef said...

Actually even piping hot cheeses like feta and brie need to be avoided according to some.

I asked if it was ok to put on homemade pizza and they sad no.

Giovanni said...

You can gobble on feta and camembert to your heart's content, so long as they're not imported. And do we even import them? I don't think so. At any rate in NZ we make all cheeses with pasteurized milk so soft cheese carry no risk of listeria.

Julie said...

I listened pretty carefully to the interview (can't listen to it again from work so can't check now, sorry) and I didn't hear any mention of the sample group being women who were overweight. The paediatrician did say that the women themselves didn't lose weight from doing the exercise. There was some discussion of using diet instead/as well as exercise to see how that affected the birth weight of the resulting babies, but the paediatrician said diets were much harder to maintain than exercise programmes so they didn't go down that path. Personally I think asking pregnant women to go a diet is all sorts of dangerous and impractical! As we're discussing in regard to the soft cheeses, there is quite a lot of dietary pressure on pregnant women already without adding something about possibly losing weight into the mix.

My impression about the soft cheeses thing is that it doesn't matter if the milk is pasteurised, because it's more about the fact that you can't guarantee that it's been refrigerated the whole time from manufacture to your plate. It also seemed to me that the advice has changed a little over the last three years - when I was pregnant with Wriggly it was No Soft Cheeses EVA, but now it seems to be Soft Cheeses OK As Long as Eaten Whilst Steaming Hot. That's what it says on the current healthy eating preggy guidelines they are handing out through doctors etc.

Alison said...

Sounds like the classic talking-about-pregnancy mistake that health providers make; that is, all comparative terms and nothing definite.

Medically, the "low birthweight" line is commonly drawn at 2.5kg. The "high birthweight" or macrosomia line is usually drawn at 4.5kg, and above and below those lines, there's a substantial increase in illness for babies. But as always, the idea that there's a firm line is ridiculous. If you have a 2.4kg full-term baby from a 140cm mother, and a 165cm father, you're probably not going to panic. Ditto for a 4.6kg baby born at 42 weeks from two tall strong parents. There is always, always variation. So I interpret that paed's advice as being to do with reducing birthweight within the really very wide "normal range" of 2.5-4.5kg. But how many lay people know that that's the normal range? In my experience so far, most women have absolutely no idea what constitutes "normal weight" for a newborn, and most seem to actually underestimate the average by around half to one kg.

Talking about low/er and high/er birthweights without any actual reference figures is utterly useless for the vast majority of people. Incomplete information can be so misleading, and health providers need to get their heads around that before they go out and make these statements to the public. The last thing we need is pregnant women pushing themselves to keep their babies' weights down if they're already overworked and stressed and not giving themselves the downtime they need in pregnancy.

I can see lots of reasons for recommending exercise in pregnancy. This is not a particularly good one, except that women have learned such a fear of "big babies" that it's more likely to motivate them than other, much more certain outcomes.

Alison said...

Stef, there is no good evidence for banning heated cheeses; the concern is listeria, and it's easily killed by heat. As Giovanni points out, the cheese recommendations are extremely conservative in NZ anyway, given all our cheeses are pasteurised.

Alison said...

Sorry for the double post. Had all sorts of problems commenting this morning.

Julie said...

Deleted the double comment Alison, thanks for your info, that puts it in better context.

I think with the preggy diet stuff ultimately if a woman has decided not to eat something because she feels it's a risk then you have to respect that even if it's medically crap. And conversely if another woman decides to eat something you think is a risk then it's her call on that too.

Julie said...

Oh and my favourite hot feta dish is lamb and feta toasted sandwiches, nom nom nom.

Alison said...

Yeah, I agree that women need to decide which guidelines they're going to take, but that's why I don't like to see them given advice that takes caution to an extreme, without explanation. It doesn't provide any scope for women to assess the risks for themselves.

Julie said...

That's it exactly Alison! That's what worried me so about this media interview.

Also, so want a hot lamb and feta toasted sandwich right now.

Lucy said...

At the presentions at the end of the University of Otago Christchurch summer studentship programme this year, one girl talked about her project designing birth weight charts to take into account parental differences - the key one I remember was that macrosomia was being overdiagnosed for Pasifika babies, and underdiagnosed for South and East Asian babies.

The main message was that, as Alison says, one size absolutely does not fit all for deciding whether a baby's weight is healthy - even one *range* doesn't. It was quite interesting.

Azlemed said...

I am overweight, but none of my 4 babies have been over 4kg, I have lost weight during all of my pregnancies, not due to sickness either, not all obese mums produce obese babies....

As for the eating thing, its changed with each pregnancy I have had, with the first two ham was a no no, now its ok if its piping hot, same with chicken, I think its about keeping safe and being aware of what you put in your mouth, its all huge though compared to 30 years ago when our parents were having kids,

my mum ate raw oysters etc while pregnant with me, they didnt have the worries about food, but then most of their food was prepared at home not packaged, or deli etc like now so possibly some of the potential risks werent there....