Effects of prenatal exercise on incidence of congenital anomalies and hyperthermia: a systematic review and meta-analysis

Objective To investigate the relationships between exercise and incidence of congenital anomalies and hyperthermia. Design Systematic review with random-effects meta-analysis. Data sources Online databases were searched from inception up to 6 January 2017. Study eligibility criteria Studies of all designs were eligible (except case studies and reviews) if they were published in English, Spanish or French, and contained information on population (pregnant women without contraindication to exercise), intervention (subjective or objective measures of frequency, intensity, duration, volume or type of exercise, alone [ exercise-only ] or in combination with other intervention components [e.g., dietary; exercise + co-intervention ]), comparator (no exercise or different frequency, intensity, duration, volume or type of exercise) and outcome (maternal temperature and fetal anomalies). Results This systematic review and meta-analysis included \u27very low\u27 quality evidence from 14 studies (n=78 735) reporting on prenatal exercise and the odds of congenital anomalies, and \u27very low\u27 to \u27low\u27 quality evidence from 15 studies (n=447) reporting on maternal temperature response to prenatal exercise. Prenatal exercise did not increase the odds of congenital anomalies (OR 1.23, 95% CI 0.77 to 1.95, I-2=0%). A small but significant increase in maternal temperature was observed from pre-exercise to both during and immediately after exercise (during: 0.26 degrees C, 95% CI 0.12 to 0.40, I-2=70%; following: 0.24 degrees C, 95% CI 0.17 to 0.31, I-2=47%). Summary/Conclusions These data suggest that moderate-to-vigorous prenatal exercise does not induce hyperthermia or increase the odds of congenital anomalies. However, exercise responses were investigated in most studies after 12 weeks\u27 gestation when the risk of de novo congenital anomalies is negligible

Prenatal exercise is not associated with fetal mortality: a systematic review and meta-analysis

Objective To perform a systematic review of the relationship between prenatal exercise and fetal or newborn death. Design Systematic review with random-effects meta-analysis and meta-regression. Data sources Online databases were searched up to 6 January 2017. Study eligibility criteria Studies of all designs were included (except case studies) if they were published in English, Spanish or French and contained information on the population (pregnant women without contraindication to exercise), intervention (subjective or objective measures of frequency, intensity, duration, volume or type of exercise, alone [ exercise-only ] or in combination with other intervention components [eg, dietary; exercise + co-intervention ]), comparator (no exercise or different frequency, intensity, duration, volume and type of exercise) and outcome (miscarriage or perinatal mortality). Results Forty-six studies (n=2 66 778) were included. There was \u27very low\u27 quality evidence suggesting no increased odds of miscarriage (23 studies, n=7125 women; OR 0.88, 95% CI 0.63 to 1.21, I-2=0%) or perinatal mortality (13 studies, n=6837 women, OR 0.86, 95% CI 0.49 to 1.52, I-2=0%) in pregnant women who exercised compared with those who did not. Stratification by subgroups did not affect odds of miscarriage or perinatal mortality. The meta-regressions identified no associations between volume, intensity or frequency of exercise and fetal or newborn death. As the majority of included studies examined the impact of moderate intensity exercise to a maximum duration of 60 min, we cannot comment on the effect of longer periods of exercise. Summary/conclusions Although the evidence in this field is of \u27very low\u27 quality, it suggests that prenatal exercise is not associated with increased odds of miscarriage or perinatal mortality. In plain terms, this suggests that generally speaking exercise is \u27safe\u27 with respect to miscarriage and perinatal mortality