Macrosomia – what is it?

When I attended the Diabetes UK Professional Conference I sat in on a talk about Macrosomia. The talk was titled ‘Macrosomia: Is it inevitable, is it preventable and does it matter anyway?’ The talk was broken down into sections featuring presentations from various speakers. The talk ran as follows:

  • 11.40 – Can we accurately predict macrosomia and should this effect timing of birth? – Edward Mullins, London.
  • 12.00 – Can continuous glucose monitoring reduce the risk of macrosomia: Lessons from the CONCEPTT study – Helen Murphy, London.
  • 12.20 – The consequences of macrosomia to later life: How real are they? – David Dunger, Cambridge.
  • 12.40 – Results from the National Pregnancy in Diabetes (NPID): Are there options for reducing macrosomia? – Nick Lewis-Barned, North Shields.

For anyone who is unsure of the term ‘macrosomia’, it means a baby who is born large for it’s gestational age. Babies who are classed as ‘macrosomic’ have a birth weight of 8 pounds, 13 ounces or over.

As a woman who is approaching her thirties (I’m 28, turning 29 at the end of this year) the talk on macrosomia was something that interested me. After I get married, starting a family seems to be the next step for myself and Bobby (at some point, we are in no immediate rush as other things such as career take precedence right now) so it only seemed right that I attended the talk. I’m not going to lie, but I came out of the talk feeling overwhelmed and quite frankly quite concerned. I think what really threw me was the intense scientific terminology and the detail into which the information went. Like I explained in my previous blog, the conference is not particularly designed for patients, but for medical professionals, so the content is vastly technical. As a patient I came away feeling like I’d heard too much. However, after I’d had time to think and reflect on the situation, it sort of made me extremely determined to be one of the type 1 diabetic women who don’t end up having a macrosomic baby. Bring on the challenge I say!

What did I learn?

First of all, there are a few concerns for mother and baby during the birth of a macrosomic baby. Due to the large size of the baby the mother may experience trauma whilst giving birth. The baby also has a much higher risk of shoulder dystocia which can be life threatening for the baby. It can also cause injury, hypoxia, cerebral palsy and stillbirth. Shoulder dystocia is where the babies shoulders become lodged behind the mothers pelvic bone because the baby is too big for the birth canal.

For most type 1 ladies out there you will probably have heard that the birth tends to be induced early. This is because the early induction does reduce the mean birth weight as a baby can grow rapidly in a matter of weeks. You may be wondering, why does this happen to women with type 1? Well, the reason why macrosomia can happen, is because a higher amount of blood glucose passes through the placenta and into the fetal circulation. The extra glucose in the fetus is stored as body fat and this is what causes macrosomia.

I found in the talk that there seems to be a correlation with babies being born big and remaining big throughout their adolescence and adult lives. Information did show that macrosomic babies are more likely to become obese or have metabolic dysfunction.



Does this mean that all babies born to type 1 diabetic mothers are going to be born macrosomic? No. Apparently during a study 1 in 2 babies born to type 1 mothers were born big for their gestational age. So there is hope for us all!

The use of CGMs (continuous glucose monitors) has been found to reduce the potential of having a large baby. For mothers using CGMs for every 5% extra time in blood glucose range reduces the outcome of having a large baby. There has also been evidence that in terms of prevention of macrosomia medical professionals need to understand more about the relationship between mother and baby during pregnancy. Reducing the amount of glucose in the blood and reducing the HBA1c level seems to really make an impact on the prevention of babies that are large for their gestational age. The mother’s BMI also makes a difference.

So, can medical professionals accurately predict macrosomia? No. But they can try. You can predict macrosomia by feel, ultrasound and blood – however – it’s not accurate. If macrosomia is suspected it will affect the timing of birth delivery. Women will be induced and possibly elected for a caesarean.

There is a vast amount of information to take in with regards to macrosomia. Is it scary? Yes. Well, in my opinion it is. There is an awful lot to consider and I know that when I am going to plan on getting pregnant, that I am going to do absolutely everything to ensure that I have a smooth running, healthy pregnancy. To be honest, I’m just scared about the complications that could possibly incur.

Saying all this though, having a macrosomic baby doesn’t have to be a traumatic experience and some children have been found to grow into healthy adolescents and adults. So it isn’t inevitable for everyone.

It’s a really difficult conversation topic to broach, especially writing about it in my blog. A helpful tool for pregnant women with type 1 is Mumsnet. There are lots of chats on there from women who are having macrosomic babies and I’m sure there will be women talking about their birth stories too. It’s not all doom and gloom, I promise. It’s just one of those things that as a diabetic woman, we need to get our heads around.

I hope this hasn’t scared anyone too much! If you do have any concerns about macrosomia, do please talk to your healthcare team. They will be able to offer out any help and advice that you could possibly need and guide you through the whole experience step by step. Like I said before, just let this make you determined to do everything possible to ensure you are giving your baby the best possible start in life. I think that’s fair to say.


Published by diabetesandtheactor

Actress, singer and type 1 diabetic.

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