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Tough workouts no problem in third trimester

Boot camps, running and even CrossFit can be safe for heavily pregnant women and their babies according to Australian Catholic University research.

The breakthrough review, which pooled the results from all relevant studies, and published in BMC Pregnancy and Childbirth, shattered decades-old advice that strenuous physical activity into the third trimester was unsafe.

The systematic review of 15 studies, including 32,000 participants, found vigorous intensity exercise posed no risk to mums or babies.

The findings were particularly informative for lead researcher and expectant mum Kassia Beetham from ACU’s School of Behavioural and Health Sciences.

“We tend to recoil at the sight of ‘fitspo’ mums pushing their bodies right up until delivery, and a lot of the available information is conflicting,” Dr Beetham said.

“The news is good for active women – appropriate vigorous physical activity into the third trimester is perfectly safe for mums and babies.”

The research defined vigorous as any exercise undertaken at an intensity of 70-90 per cent of maximum heart rate. Due to normal cardiovascular changes in pregnancy, the threshold for achieving vigorous intensity exercise is slightly lower for pregnant women than in non-pregnant populations.

Exercise in pregnancy has in the past been stigmatised based on the theory that blood flow is re-directed to the working muscles and could take away oxygen and nutrients from the growing baby.

However, the ACU research found there was no difference in birthweight of babies when their mums did vigorous exercise, or no difference in the number of babies being born small for gestational age. Risk of prematurity was also slightly less in women completing vigorous intensity exercise in the third trimester.

Healthy exercise options for soon-to-be mums include resistance training, stationary (spin) bikes, running, swimming and modified CrossFit with no jumping or bounding.

“We don’t want mums missing out on health benefits if there are no risks to the baby. If you do prefer more vigorous intensity exercise, and have a healthy pregnancy, then you should feel reassured in the safety of participating in that type of exercise,” Dr Beetham said.