How much bigger? A Q&A on gestational weight gain with Hannah Hartley

Confused about how much weight you should gain during pregnancy? Most of us are! Big Birthas Parenting Science Gang spotted Hannah Hartley’s research poster about what mothers understand about gestational weight gain at at a conference and asked her to tell us more about what she has found out.

Hannah: Hi. I’m Hannah, a PhD researcher at the University of Leeds. Thank you for having me!

My research project is about understanding women’s health behaviours (things like diet and physical activity) that have an impact on gestational weight gain. My background is in psychology.

We hope that this research will inform future interventions and weight related care during pregnancy.

The review, which is what the poster is on, is part of my PhD project. The review is about

  • bringing together other research in the area of weight management and seeing what that research has found, and
  • seeing what gaps there are that I can investigate with my research.

Essentially, the review is ‘research on research’ – the findings bring together the findings from the original research papers included in the review.

PSG B: Hi Hannah – thanks for joining us! Can you tell us what led you to this research – why does it need to be done?

Hannah: Sure. I’ve always had an interest in weight management and was really interested in hearing about the history and change in routine weighings during pregnancy in the UK.

Routine was used during the war whilst women were rationing as a tool to identify small babies. However, research in the early 1990’s suggested that this wasn’t an accurate way of identifying small babies, plus it may cause distress for some women.

So it was decided to stop routinely weighing and monitoring gestational weight gain.

PSG B: So weighing was more about finding out about the weight of the baby than assessing the mothers’ health?

Hannah: It was then, yes, but more recent debates are also around mothers’ health and long term impacts for child health.

Q: Were there any surprising things you found when you looked at the literature, or anything that you thought should have been made more of?

Hannah: I was surprised at how much of the literature was focussed on women who began pregnancy with a high BMI. There is also very little on the experiences of women who begin their pregnancy ‘underweight’.

My point of view is looking at weight management during pregnancy regardless of their starting BMI as ‘excessive’ weight gain is important regardless of women’s pregnancy start weight.

Q: I know that what counts as “excessive” varies in different countries, but does the literature suggest that mothers are aware of what excessive be?

Hannah: Yes, that’s a really good point. The UK is fairly unusual amongst high income countries in that we don’t have any guidelines regarding what counts as excessive weight gain. Lots of countries follow the institute of medicine’s guidelines from the US, some have their own, but the UK is unusual for having none.

It seems from the literature that women seem to focus more on where the weight gain is as opposed to the numerical weight gain. The location of the body seems to be more linked to how they see the weight gain in relation to the pregnancy.

PSG D: There should absolutely be guidelines. The average baby weighs half a stone by the time it’s born, add to this the weight of the placenta and the extra blood, and the fat that your body stored to make milk, there’s so much to take into consideration. It’s ridiculous that there are no guidelines. I’m pregnant now and have had to research guidelines on weight gain myself.

Q: I was interested to see that some mothers thought that physical exercise could be risky for the baby. Do you have any idea why that is?

Hannah: This is a really interesting question, and fairly complex to answer. Firstly, women sometimes form a mental of picture of the baby being subjected to movement i.e. one of the quotes talks about how running might ‘give them brain damage’ because of the ‘baby bouncing around’.

Secondly there’s all the messages women are given around ‘exercises to avoid’ which are usually orientated around avoiding high impact exercises, without being clear why that is and what they are.

And the messages women get about the importance of resting…

Resting is an interesting area and open to interpretation. For example it could refer to physical activity but also mental well-being. Someone may find it restful / relaxing to be doing exercise.

Some women also discuss the importance of avoiding being sedentary through doing active chores or ‘getting out the house’, but also not wanting to formal exercise such as going to the gym or running.

PSG F: I knew a woman from central China whose family was very concerned that her Western husband was encouraging her to exercise, while they felt it was of utmost importance that she rest physically as much as possible and eat heartily so she would have a strong baby. Perhaps people’s cultural backgrounds have an influence, even when it was their parents/grandparents who were from a different culture?

Hannah:  The review is focussed on UK studies (because of the difference in weight gain guidelines) and unfortunately within these they have not captured much diversity regarding culture. Sounds like this is an area for future research!

PSG D: I have definitely found this and I don’t think medical professionals are that well informed. I exercise regularly and the guidance generally is if you already do exercise it’s OK to keep doing it as long as you pay attention to your body and don’t push it to extremes, but I have been advised by midwives in the past to not carry on with the type of exercise I was doing and just to do yoga.

PSG H: Usually the line is “don’t do more than you did before pregnancy, and then listen to your body if you need to do less ‘ I’ve found

Hannah: These are all really interesting!!

PSG B: That’s incredible! Do you do something impressive that some midwives might not be very knowledgeable about, something like iron-woman races or climbing in hot countries?!

PSG D: I do Crossfit which has a reputation of being really tough (although I’m not at a high level by any stretch of the imagination) but luckily a lot of the people at my gym are nurses, doctors and physios, some of whom have done it themselves while pregnant so I have had good advice from them.

Incidentally one person who is a medical professional herself who works with pregnant women was told to stop doing it when she was pregnant. Luckily she knew enough to be able to modify her exercise appropriately but so many people could be getting bad advice.

Hannah: Again, another area to explore! It does seem that experiences and advice (including from HPs) vary!

PSG J: I’m late to the game but my yoga teacher says it’s not advised to do yoga for the first 14 weeks (because of the twisting). I’m not sure of the evidence base for this.

PSG D: You can go to yoga classes that are adapted to do movements that are more easily done when pregnant. I think the focus is more on the meditation aspect of yoga with some gentle stretches included. It would be interesting to see evidence though as some people might not even realise they’re pregnant for the first month or so and I don’t understand how it would impact you negatively in the early days.

Q: I wondered during pregnancy why I was weighed at my 8 week appointment but never really after this.

I was told this wouldn’t be relevant even if I was under the care of an endocrinologist during pregnancy due to my thyroxine. Why is the approach so clearly different between areas and also from other countries? Surely the consultant led care would warrant weighing and also my age as I got tested for GDM (gestational diabetes).

Hannah: Hi, I don’t know the specifics for your circumstances, but routinely in the UK, women are weighed at the first formal antenatal appointment so that they can get an estimate of pre-pregnancy BMI because it is this that shapes future tests and pathways, rather than weight gain.

This is also true for GDM (gestational diabetes)  – BMI at the first appointment (booking visit) is a risk factor for GDM so can be considered when deciding whether to test for GDM.

As for why routine weighing doesn’t happen in the UK, this is partly because of the ‘quality’ of the evidence and it’s transferability (e.g. because it’s been carried out in other countries and questions as to whether it is as applicable here).

PSG M: I couldn’t stop eating in the first trimester and gained about a stone in the first month. It’s not always a good indicator of pre-pregnancy BMI!

Hannah: Yes, on a population basis, it is as good an estimate as health professionals can obtain. But as you mention, weight can change quite early on. Plus there’s the issue that women vary in terms of the number of weeks’ pregnant that they are at the time of their first appointment (and for various reasons, including to do with systems).

Q: I have read that the best health outcomes for the baby are with moderate weight gain in pregnancy, regardless of starting weight.

I was interested in that from the perspective of having experienced hyperemetic pregnancies, where in the UK I was told repeatedly that weight loss would not harm the baby, yet while pregnant in another country, the obstetrician told me i had to get calories in, or the baby would suffer. Is there much actual hard evidence on this?

Hannah: Where recommendations do exist, they do tend to advise some weight gain.

It may partly be that health professionals vary within and between different settings as to how holistic they are being. For example, where a woman is battling extreme sickness, levels of nausea and dehydration, it may not be helpful to also have anxiety about the baby being deprived in some way, and a health professional may be mindful of this too in terms of an individualised perspective.

PSG F: That is interesting, as I had been thinking in terms of at what point they go to the next level of treatment, rather than the perspective of psychology. Presumably, then, it would also work the other way, of HCPs perhaps not wanting to give too much attention to exercise and weight gain (worry of too much, that is) in case of simply adding something new for a mother to be stressed about?

Q: Where do you think popular ideas about weight gain in pregnancy come from?

Hannah: I guess there’s quite a mix of ‘popular’ ideas about weight gain.

The research suggests that some people see pregnancy as the time in their life of relative freedom and less concern towards weight gain. Whilst it’s discussed by other women that they feel a pressure e.g. from health professionals and others passing comment, to limit their weight gain.

Another interesting issue is that speaking with women, they may interpret weight management as weight loss, which in the context of pregnancy may not be meant by the term.

PSG O: There’s so much pressure on women generally to think about weight 🙁

I love it when I hear people take pregnancy as time off from that pressure, but it’s not always like that is it 🙁

Hannah: Yes, for some people it is, but for a lot of women they can feel more in the spotlight, and that even strangers may pass comments about their weight that wouldn’t happen outside of pregnancy.

PSG H: The fact that **&%! slimming world is advertised during pregnancy…

Q: I also wonder whether a woman’s weight gain in pregnancy is sometimes more fluid than fat – I personally gained 3 stone but I think a lot of that was fluid retention as my feet ,ankles and calves got really swollen (no it wasn’t pre-eclampsia). I think due to my short size baby was compromising my lymphatic drainage in my lower body.

PSG K: Totally this!

Hannah: Yes, and this is partly why routine weighing isn’t used in the UK – because it’s not necessarily clear what is contributing to the weight.

Q: What did you think of the evidence base for treating women with a high BMI at conception as being high risk?

Did you find that it was high BMI at conception that was actually used, or high BMI at booking appointment (which can be 12 weeks pregnant)?

Hannah: High BMI at booking is usually used. And as mentioned above may not necessarily be accurate about conception BMI. Far less is known about BMI at conception and onward risks.

Q: I wonder if there’s any research about how stopping smoking (which many people do when they find out they are pregnancy) interacts with pregnancy weight gain?

Hannah: Again, such an interesting point, but research tends to focus on behaviours in isolation rather looking the reality of people’s lives. Often these things are linked, but not fully unpacked within the literature.

Q: I’m pregnant now and was weighed at my booking in appt and my BMI was fine and have been given no further guidance since so I’m having to do research myself. It’s my third so I’m not too stressed but it’s massively confusing when there are no definitive guidelines. There are many posters up at the clinic I go to about ladies with high BMI but nothing for anyone else which I feel can lead to people seeking advice from less reputable sources.

Hannah: It can be such a challenge for people navigating the huge amount of information that is out there and knowing what they can trust.

Hannah: It’s been really good chatting with you all, thank you for such thought-provoking comments. It looks as though there are some potential research questions in here that could be followed up!

Chorus of voices: Thank you so much for coming Hannah, such an interesting area of research!

Did this interest you? Why not check out some of our other Q&A sessions including:

You can find loads of other on the Q&A page of our website.

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