Pregnant and Overweight

Its not as if anyone intends to be overweight or obese. There are many factors that affect a person’s weight but being pregnant and overweight or obese can increase the risk of complications both for the pregnancy and the baby.

In Western countries 28% of pregnant women are overweight and 11% are obese. In the UK 33% of pregnant women are overweight, 23% of pregnant women are obese. That’s a whopping 56% of pregnant women are over the recommended BMI for their height.  We all know the reasons for being overweight and usually its lack of exercise, but with jobs and lifestyles as they are today, this is all too common, not only for women but men also. I think we all can relate to this!

There are added risks being pregnant and overweight/obese.  Obesity is a condition characterised by excess of body fat and a BMI over 30.  This doesn’t mean you are not healthy, but being overweight is an added stress on the body, coupled with a pregnancy, this can add in significant complications such as pre-eclampsia, hypertension, diabetes, thromboembolism. It can also raise the risk of fetal abnormalities.  This is naturally something that every mother worries about. She would naturally want to be healthy and give her growing baby the best chance to be healthy.


How Does Being Overweight Affect Your Baby Scans? 

This is probably something that you’ve not thought about before. We are all used to going for scans for a torn ligament or sprain or for back pain, but these are different scans that work in a different way and could not be used for a baby scan.  In the past, before ultrasonography was available, it was down the obstetrician and midwives to assess the baby by feeling the position of the baby, listening to the fetal heart and measuring the fundal height to work out delivery dates.  If there was a concern about pelvic shape and ability to deliver, they may even have performed an x-ray. This is much safer nowadays than it was back in the 1890’s.

Baby scans work by sending high frequency sound waves through the abdomen and through the uterus.  Its perfectly safe for you and your baby, so don’t worry.  The sound waves bounce off the fetus and the echos then  return to the probe and are turned into images on the scan monitor.

If the body fat is raised between the uterus and abdominal wall, i.e.  over the belly, the sound waves have much more body tissue to travel through. The echo comes back weaker and so the images are lacking in detail and look fuzzy, making the fine details difficult to observe, bearing in mind that at 12 weeks, Mr Penman is performing a Nuchal scan to check for chromosomal abnormalities and an early gender scan.

Im sure you can imagine how small these structures must be if I tell you that at 12 weeks the baby is approximately 5.4cm and weighs 14g. An average woman’s ring finger from tip to knuckle is about that long.  Mr Penman is then trying to see the fat pad at the back of the baby’s neck to measure it for the Nuchal assessment and also trying to get a good view of between the legs to be able to accurately assess the gender….. if you want to know that is !


Concerns For The Fetal Medicine Specialist – Mr Penman 

When the fetal medicine specialist, a consultant such as Mr Penman, scans a lady with a raised BMI, he has several concerns :

  • The scan images lack detail and are fuzzy.
  • It is more difficult to assess the wellbeing of the fetus, the structures that are forming. This is a concern to the fetal medicine specialist because the primary reason for the baby scan is to assess the baby is growing normally.
  • A certain amount of time is allocated for baby scans. This is usually much more time than is required, ensuring that no one is kept waiting beyond their appointment time. However it takes a lot longer to scan a mother with a raised BMI, particularly if the BMI is over 39 because of the increased body tissue.
  • More appointments are needed because of the difficulty in scanning which for a private consultant like Mr Penman means more cost for the mother.
  • It is much more difficult to get good scan pictures  for the mother.  3D and 4D scanning is almost impossible with mothers with BMI’s over 35, regardless of getting baby to move around.
  • Many patients are unaware that there are limitations to baby scanning if they have a significantly high BMI, for example… over 40.  Even with the best tissue harmonic imaging probes or lower frequency transducers (scan probe), there is still limited evaluation of the fetal anatomy.


Managing the Appointment 

Mr Penman is a very experienced fetal medicine consultant and does his best to get the best possible images he can during a baby scan.   It is very difficult to try and tactfully explain the physics of ultrasound without hurting feelings and offer a reason for the poor quality scan images.


But he always goes above and beyond the expected with all his scans to not only check the baby is healthy and developing properly but also to get images for the mother to keep as mementoes.


Whilst it is not always possible to give 3D and 4D(realtime)  images because of this reason, he will ensure that all his measurements and checks are accurate as is possible, explaining them thoroughly before the appointment ends.  He appreciates that it is a worrying time for any mother, to know that her baby is healthy and developing normally and he always strives to get the best images he possibly can.



1 Comment

  1. This is interesting, I hadn’t thought through that to get a good image, you needed to have less body fat. Im on the chubby side myself, so its good that Mr Penman is considerate and is sympathetic to the mother’s feelings.

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