


However, current guidelines for pregnancy are not trimester-specific. It seems likely that the increasing physiological demands during each trimester of pregnancy require variation in exercise training accordingly. Indeed, reduced fetal movement after vigorous intensity exercise in the third trimester has been shown in studies with both conditioned and unconditioned mothers. The combination of these adaptations challenges the greater demands required by the fetus during pregnancy. Physical exertion demands greater substrate utilisation, and as such re-directs blood to the working muscles, whilst also generating heat and excess by-products. So while moderate intensity exercise throughout pregnancy is beneficial, it is not known whether vigorous intensity exercise is detrimental, particularly in the third trimester when the needs of the fetus are greater.ĭecreases in utero-placental blood flow occurs during vigorous intensity exercise, and has been shown to result in fetal bradycardia. Research has shown that fetal hypoglycemia in hypoxic conditions can result in infants born small for gestational age. This is clinically important as birth weight is the single most important predictor of neonatal morbidity and mortality. However, studies investigating the effects of vigorous intensity exercise on birth weight have been mixed. Moderate intensity aerobic exercise throughout pregnancy is known to result in lower caesarean delivery rates, lower incidence of gestational diabetes and hypertensive disorders, decreased maternal weight gain, and improvements in antenatal and postnatal depression, and has not been found to negatively affect birth weight.
#THE NEW HIGH INTENSITY TRAINING PORTUGUES REGISTRATION#
PROSPERO trial registration CRD42018102109. Further research is needed on the effects of vigorous intensity exercise in the first and second trimester, and of exercise intensity exceeding 90% of maximum heart rate. Conclusionsįindings from this meta-analysis indicate that vigorous intensity exercise completed into the third trimester appears to be safe for most healthy pregnancies. Women who engaged in vigorous physical activity had a small but significant increase in length of gestational age before delivery (mean difference = 0.21 weeks, n = 4281) and a small but significantly reduced risk of prematurity (risk ratio = − 0.20, n = 3025). Moreover, no significant increase existed in risk of small for gestational age (risk ratio = 0.15, n = 4504), risk of low birth weight (< 2500 g) (risk ratio = 0.44, n = 2454) or maternal weight gain (mean difference = − 0.46 kg, n = 1834).

No significant difference existed in birthweight for infants of mothers who engaged in vigorous physical activity and those who lacked this exposure (mean difference = 8.06 g, n = 8006). Ten cohort studies ( n = 32,080) and five randomized control trials ( n = 623) were included in the systematic review ( n = 15), with 13 studies included in the meta-analysis. The studies were required to include an intervention or report of pregnant women performing vigorous exercise during gestation, with a comparator group of either lower intensity exercise or standard care. Study designs included in the systematic review were randomised control trials, quasi-experimental studies, cohort studies and case-control studies. MethodsĮlectronic searching of the PubMed, Medline, EMBASE, Cochrane Library, Web of Science and CINAHL databases was used to conduct the search up to November 2018. The aim of this systematic review was to investigate the effects of vigorous intensity exercise performed throughout pregnancy, on infant and maternal outcomes. Fetal growth is dependent upon utero-placental vascular supply of oxygen and nutrients from the mother and has been proposed to be compromised by vigorous intensity exercise in the third trimester.
