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Freeflow Article: A quick guide to plus size pregnancy care

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A quick guide to plus size pregnancy care. 

By Alice Keely


Instagram @theheavyweightmidwife



A bit of context: my guide centres on the current UK pregnancy care guidelines from the Royal College of Obstetricians and Gynaecologists (RCOG), which are used by all NHS Trusts in the UK. (It is very similar to the American College of Obstetricians and Gynecologists guidelines too and other national guidelines round the world). Based on these national documents, local providers formulate their own maternity care guidelines, which means different guidelines vary. So, check with your midwife or doctor regarding local guidelines, but remember they are guidelines, a starting point for conversations about your choices and your pregnancy care. 


The guide is not intended to be a complete overview of every aspect of your pregnancy care. I’ve mostly singled out aspects which relate to plus-size care, to help you know what to expect and why it might be offered. Remember that every single aspect of your care is what is recommended, and it is up to you to ask questions to help you decide what’s right for you.

KEY POINT A lot of what midwives do focuses on the detection and elimination of risk for mum’s and babies. Midwives look after all mums-to-be and we are trained to detect issues (which is good!) but some are not very good at discussing the risks of these complications arising. It can also mean the conversations you have don’t focus on you, your baby, and all the positive stuff you can do to keep healthy and enjoy your pregnancy, but instead focus too much on risks and make you feel worried.

My belief is that things can get very distorted when we think about risks and complications. For any of the problems you may have heard about, if you are healthy and well, in plus size pregnancy your risk overall of complications is LOW, no matter what you weight is. Any given risk MIGHT be a bit higher because of your weight (and I do mean a bit!), but overall it is low. LOW! (Yes, I’ll say it again). By far the most likely outcome for you will be a straightforward pregnancy, birth and a healthy baby.

It is likely that it’ll feel to you like a lot of discussion about risk happens with your midwife and maybe with doctors, and then what happens is that you end up feeling like complications are likely to happen, when this simply isn’t the case. So, I’m putting this out there for balance and as my main take-home message to you: ‘Higher risk’ does NOT mean ‘High risk’!

Included below are some aspects of care that may differ if you are plus size, or that are highlighted in the UK guidelines as particularly important. It isn’t a full list of all aspects of the routine antenatal care you’ll receive. It’s tailored to pregnancy care in the UK, but can be useful for anyone who is pregnant, anywhere in the world.

Blood pressure

Your blood pressure check is a measurement of how hard your heart is working as it pumps blood around your body. Normal blood pressure changes happen during pregnancy, as your baby grows and your body makes more blood because you are pregnant, but it is very important to measure you blood pressure all the way through pregnancy. So, you will have it checked at your first appointment and then every time you see your midwife or doctor. If you have bigger arms, make sure the midwife is using a large cuff for this (as a guide, the cuff should wrap around with plenty of overlap, not just meet together, and there are measurement lines on the cuff for the midwife to use). It is very important to get an accurate measurement right from your first appointment, as this is recorded as your ‘normal’, to check for rising blood pressure later in pregnancy. A cuff that is too small will likely record an inaccurately high measurement. So please don’t let any potential embarrassment stop you checking the cuff being used is big enough. Sometimes the bigger ones aren’t readily available (there may be one within a whole clinic for e.g.) but your midwife must use one to get that accurate reading.

Body Mass Index (BMI)

You will be asked if the midwife or health care assistant can measure your height and weight. This is to calculate your Body Mass Index (BMI). This is to categorise your BMI as ‘underweight’, ‘normal’ ‘overweight’ or ‘obese’ with three classifications: ‘obese’ (BMI over 30), ‘severely obese’ (BMI over 35), ‘very severely obese’ (BMI over 40). Your recommended plan of care will be formulated from there and may involve you being referred to see a consultant obstetrician and perhaps other specialists too.

Folic Acid (Folate)

If your BMI is calculated as more than 30, you will be recommended to take 5mg of folic acid daily, a higher dose than the usual 400mcg (or 0.4mg). If you haven’t taken this higher dose from before pregnancy or early in pregnancy, please try not to worry – you do get folate from food sources, and if you’ve taken a lower dose up to now, this is still very beneficial. In addition, the RGOC guidelines acknowledge ‘there is uncertainty about whether 5 mg is the appropriate dose’ of folic acid for women with a BMI more than 30. There is a lack of clear evidence on this, so the guidelines are based on the best available evidence. And please remember that, across the whole population, neural tube defects in babies – the ones that folic acid can lower the risk of – are very rare.

Vitamin D

All pregnant women are recommended to take a supplement of 10 micrograms of Vitamin D between September and March (during winter). There is no evidence that taking a higher dose is more effective – or that a higher does is safe –  and therefore 10 micrograms will be recommended to you during pregnancy.

Glucose Tolerance Test (GTT)

If your BMI is calculated as 30 or greater, you’ll be recommended to have a glucose tolerance test (GTT) during pregnancy, and maybe another repeat one later on. A GTT measures how well your body is processing the sugar you consume through the food and drink in your diet. It is done in the early morning and takes a couple of hours to complete. It involves you skipping breakfast, going along to the clinic or hospital, having a blood sample taken, then drinking a measured amount of a sugary drink (usually Lucozade). You then wait for a set time (2 hours usually) before having another blood sample taken. The first blood sample is tested to measure your blood sugar levels when you haven’t any consumed sugar for several hours (a baseline), then the second blood sample is tested to measure how well your body copes with processing a large amount of sugar quickly. The result will be a number, and if you score above a certain number (this actually varies slightly in different countries!) you’ll be diagnosed with gestational diabetes.

It is important to remember however, that most plus-size women DO NOT develop diabetes in pregnancy!


If you have a BMI of more than 35, you may be recommended to take 150 mg Aspirin daily once you are twelve weeks pregnant and for the rest of your pregnancy, but this is based on individual clinical factors (if this is your first baby or if you are having twins for e.g.). There is good evidence for this recommendation, but of course ask questions so you are happy with your decision.

Thrombosis in Pregnancy

Thrombosis is when a blood clot develops, usually in a person’s leg. Pregnancy is a time when blood clots are slightly more likely to develop compared to when you are not pregnant, so your care includes helping to prevent this happening. Your weight is a factor, but again, the overall risk is low. You should expect an individual assessment of how best to prevent thrombosis (if you’ve had one before, if people in your family have had thrombosis, any medical conditions etc) and then to have your care planned accordingly. Depending on your BMI calculation and individual circumstances, you may be advised to take injectable blood thinners during your pregnancy. Again, ask questions to ensure you understand the reasons for this and feel in control of the decision that is made.

Pregnancy Diet and Weight Gain

It surprises some people to learn that we have absolutely no formal guidance at all in the UK for weight gain in pregnancy. Some people do not want guidance, while others feel it would be useful – we all have different preferences and needs. When asked, some midwives might quote US guidelines from the Institute of Medicine (IoM) and you may have seen these on the internet. What I’ll flag here is that these have been considered – and rejected – by experts in the UK, who favour a focus on healthy eating in pregnancy. So, what you can expect from your midwife is the same advice given to any pregnant woman: there is no evidence-based advice tailored for plus-size pregnancy.

Ultrasound Scans

Pregnancy ultrasound scans are probably going to be a really important event in your pregnancy, providing you with your first chances to see your baby. They can be exciting and can reassure, but they can cause anxiety too. Within NHS standard care you’ll be offered two routine screening pregnancy scans, one at around 10-14 weeks (often called the 12 week scan or dating scan) and another at around 20-22 weeks (often the called 20 week scan or anomaly scan), but you may also be offered scans after that to monitor your baby’s growth right through pregnancy. These different types of scans are designed to provide different information for your health professionals and for you. Below is a summary of what the different scans are for, but first of all, general things to think about if you’re plus-size:

Ultrasound scans involve lying on your back and revealing your tummy. So…. practicalities!! Wear a top and skirt/trousers or similar, rather than a dress or other all in one (jumpsuits/playsuits are a big NO!!) Usually, it’ll just be you, whoever you want to accompany you and the sonographer in a small room with the equipment. Sonographers are specially trained health professionals, who are sometimes also midwives or doctors, but usually not. The sonographer will use a cold gel to help slide a probe over your tummy and your baby’s image will appear on a screen that everyone can see. The sonographer will talk you through what he/she can see during the examination and you’ll be able to ask questions. The sonographer is an expert in performing the scan, but usually they won’t be able to answer questions relating to other aspects of your pregnancy.

Ultrasound scans can sometimes be more difficult to perform for a number of potential reasons. One of these can be if you have a larger tummy due to your weight, but please be reassured that it is not necessarily going to make it difficult! Ultrasound waves are very powerful, so it certainly won’t be the case that there won’t be an image of your baby available. Some women feel self-conscious and nervous, especially before their first scan, as it is an intimate examination. I’d encourage you to tell the sonographer if you’re nervous – and why – if you possibly can. It will help you have a more open discussion.

The 12 week/dating scan is the one which calculates when you got pregnant and when your baby is due. It may also form part of screening for Down’s Syndrome or other conditions, if you choose to have this screening. It will also confirm whether you are having just one baby…. or more!

The 20 week scan allows the sonographer to check over the anatomy of your baby in much more detail, as he/she is bigger by now, including the structure of your baby’s heart in detail. They can also check the position of your placenta. This is the exciting time when usually the baby’s sex can be identified, so let your sonographer know before you start if you want to know or not.

Depending on your what BMI measurement is early in pregnancy, you may also be offered growth scans, which are usually done at around 28 weeks and 36 weeks of pregnancy. Once your pregnancy progresses beyond 20 weeks, the midwife usually monitors your baby’s growth by feeling your tummy – she can get a lot of important information from this – and by measuring the size of your uterus (or womb) with a tape measure. This can be a bit inaccurate and it can be more difficult to do if your tummy is bigger because of your weight. So, growth scans might be offered to you, which are more accurate for measuring growth – but it’s important to know they’re not perfectly accurate for assessing growth or predicting a baby’s birthweight, for anyone, regardless of their size or weight.

I hope this quick guide has helped you know more about what to expect from your NHS pregnancy care. There are loads more things to think about and plan for, not least planning for your baby’s birth!


If you haven’t already, sign up to The Heavyweight Midwife Facebook group, follow me on Instagram and if you want more, I have an online Plus Pregnancy Programme available to buy.

Remember that midwives and doctors are there to help you have a healthy and happy pregnancy. Have courage, ask questions and reach out to me if you need that extra support. All the very best for your happy and healthy pregnancy!




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