Using ultrasound to measure pregnant women's abdominal fat could be the best way to assess risks for overweight or obese mothers, a new study says.
Research from the University of Sydney has found that one type of fat is riskier than another for mothers and unborn babies.
In a study recently published in Obstetric Magazine, lead author Professor Ralph Nanan found more than 50 per cent of Australian pregnant women were either overweight or obese.
The study found the risk of developing complications such as hypertension or diabetes or the need for a caesarean section rose with obesity levels.
But not all obese women were equally likely to develop such complications.
"What we found is that how the fat is distributed in the body is a significant factor when judging weight-related health risks," Prof Nanan said in a statement on Thursday.
"Fat around the inner organs, referred to as visceral fat, is more dangerous than peripheral fat, the fat around our extremities."
Prof Nanan said the most accurate diagnostic tool possible was needed to decide if stomach fat was a sign of dangerous fat around organs.
A further study led by Prof Nanan used ultrasound to measure abdominal fat thickness, also known as subcutaneous fat.
Subcutaneous fat is a highly accurate indicator of the levels of visceral fat.
In the study, published on Wednesday in the Australian New Zealand Journal of Obstetrics and Gynecology, University of Sydney and University of Melbourne researchers analysed 1200 ultrasound images of pregnant women.
Prof Nanan said the simple, safe and inexpensive measurements gave a much better predictor of obesity-related pregnancy outcomes than routinely used measures such as the Body Mass Index (BMI).
The BMI is calculated by simply using a woman's weight and height.
Prof Nanan said the results meant maternal abdominal fat thickness could be used as a more accurate measure to assess risks for overweight or obese mothers.
"This can help us with management of possible risk cases including judging whether and when to transfer a soon-to-be mum to a specialist birthing centre," he said.
Better information could mean pregnant women avoided unnecessary interventions and it would save money for the health system, Prof Nanan said.