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Exercise throughout pregnancy is safe and beneficial

It may shorten first-stage labour and cut risk of C-section or excessively large baby

Louise Prime

Thursday, 13 October 2016

Strenuous exercise during pregnancy is safe and may be beneficial for the baby, according to a team of experts from the International Olympic Committee (IOC). In their consensus statement,* published today in the British Journal of Sports Medicine, they said that exercise does not increase the risk of premature birth, induced labour, epidural anaesthesia, episiotomy or perineal tears, or forceps or vacuum deliveries – and it reduces the chance of the baby being excessively large.

The IOC expert committee said that despite the maternal health benefits of exercise, there have been long-standing concerns about its potential adverse effects. These have included fears that exercising might result in inadequate foetal oxygenation (and thus ominous foetal heart rate (FHR) changes and possibly miscarriage); that exercise-induced changes in uterine blood flow (particularly in women training at elite levels) might have an adverse impact on foetal birth weight; and that strenuous exercise increases the tone of the pelvic floor muscles, possibly leading to prolonged labour, pelvic floor and perineal trauma and the need for instrumental delivery and caesarean section.

The IOC team conducted a systematic literature search of the available published evidence on how strenuous exercise affects the developing foetus, labour and birth outcomes.

They said in their statement that, generally, although strenuous exercise speeds up foetal heart rate, this is only temporary, with the heart rate returning to normal once exercise is stopped – but the quality of evidence in elite athletes is very poor. They also said they had found strong evidence that exercise during pregnancy reduces excessive birthweight, without boosting the risk of underweight at birth, and moderately good evidence that it neither boosts the risk of premature birth nor reduces Apgar score – but again, there was little evidence from elite athletes.

They found no evidence on whether or not strenuous exercise reduces the risk of tissue trauma and muscular tears during delivery; and little regarding its impact on the risk of caesarean delivery. But there was ‘moderately good evidence’ that regular exercise does not prolong labour, and might even shorten it; though again, this has not been researched in elite athletes.

They concluded that:

  • Elite athletes planning pregnancy might consider reducing high-impact training routines in the week after ovulation, and avoiding repetitive weight training during the first three months of pregnancy, as some evidence suggests this may be linked to a raised risk of miscarriage.
  • There is little risk of abnormal foetal heart rate response when elite athletes exercise at <90% of their maximal heart rates in the second and third terms of pregnancy.
  • Baby birthweights of exercising women are less likely to be excessively large (>4000g) and not at increased risk of being excessively small (<2500g).
  • Exercise does not increase the risk of premature birth.
  • Exercise during pregnancy does not increase the risk of induced labour; epidural anaesthesia; episiotomy or perineal tears; forceps or vacuum deliveries.
  • There is some encouraging evidence that the first stage of labour is shorter in women who exercise regularly.
  • There is also some encouraging evidence that exercise throughout pregnancy may reduce the need for caesarean section.

* Bø K, Artal R, Barakat R, et al. Consensus statement: Exercise and pregnancy in recreational and elite athletes: 2016 evidence summary from the IOC expert group meeting, Lausanne. Part 2—the effect of exercise on the fetus, labour and birth. Br J Sports Med 2016 ;0: 1–9. doi: 10.1136/bjsports-2016-096810 doi 10.1136/bjsports-2016-096810.

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