RESEARCH finds obese or underweight pregnant women are at a significant increased risk of complications.

Researchers at the University of British Columbia in Canada examined data collected on 743,000 pregnant women between 2004 to 2013 to determine if pre-pregnancy BMI (body mass index) was associated with severe maternal morbidity, reports 7 news.

The study, published in journal JAMA, found conditions such as sepsis or acute kidney failure were more common for women who had high or low BMI before conception, and the risk got greater as the BMI increased.

Their risk of dying was also greater.

Obese women with a BMI of 40 or greater were at 61 per cent increased risk of maternal mortality, while underweight women – a BMI less than 18.5 – were at a 28 per cent increased risk of dying from complications compared to women with a normal BMI (18.5 to 24.9).

“Among pregnant women in Washington State, unhealthy pre-pregnancy BMI, compared with normal BMI, was associated with a small absolute increase in severe maternal morbidity or mortality,” the authors concluded.

Obstetrician Dr Gino Pecoraro – the Federal Australian Medical Association Spokesperson for Obstetrics and Gynaecology – says this large study provides even more compelling reasons for women planning a pregnancy to ensure they are in the normal weight range.

“Underweight women were 1.2 times more likely to suffer significant complications while overweight women showed a steady weight-related increase in risk up to 1.4 times that of their normal weight counterparts,” said Dr Pecoraro.

“While the study was undertaken in the US, Australian figures are likely to be similar and there is no reason to expect the experience in our country to be different,” he said.

However he did note that the observational study only found an association and was not able to say that the increased weight caused the problems.

Gaining weight between pregnancies also increases the risk of your child suffering from a life-threatening condition. Read more on that HERE.

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  • All things in moderation. Pregnancy is hard enough without being unhealthy when you commence your journey.


  • Being healthy is extremely important particularly through pregnancy.


  • So thankful I was a healthy weight throughout my pregnancy.

    • My weight increased at average rates during each pregnancy.


  • I started underweight but put on 30kg. Not underweight anymore!


  • Yes, nowadays a lot of doctors look more at the waist circumference than at the BMI for example. I even heard of people measuring the wrist circumference as a measure of risk of future cardiovascular diseases, in particular in children.


  • I really struggle with the use of BMI as a health indicator. It makes no sense, particularly in those who are at either end of the height spectrum. There are better measures already known, why aren’t they used?

    As someone who can carry lean muscle and be completely ‘cut’ barring my pregnancy apron of skin and still be considered overweight, I won’t be judging anyone’s health based on BMI.


  • It would be exceedingly beneficial to have an Australian study relevant to our society and one that also results in clear indicators rather than associations as stated in the article. The article concludes with not being able to state that increased weight caused problems.


  • Our bodies are amazing. We probably all heard of the stories that women in wartime who were underweight and under high stress, trauma and fear, still were able to conceive and give birth.
    But more complications are likely to happen when under or overweight.


  • It is very important for the safety of mum and baby


  • Starting the pregnancy with a healthy weight, is surely the best way to go.


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