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 ‘very low’ quality evidence from 14 studies (n=78 735) reporting on prenatal exercise and the odds of congenital anomalies, and ‘very low’ to ‘low’ 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, I2=0%). A small but significant increase in maternal temperature was observed from pre-exercise to both during and immediately after exercise (during: 0.26°C, 95% CI 0.12 to 0.40, I2=70%; following: 0.24°C, 95% CI 0.17 to 0.31, I2=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’ gestation when the risk of de novo congenital anomalies is negligible.
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Contributors MHD, SM-R, MFM, GAD, KBA contributed to the conception of the study. MHD, SM-R, MFM, GAD, KBA, AJG, NB, VJP, CEG, LGS, RB contributed to the design of the study and development of the search strategy. LGS conducted the systematic search. CY, AK, RJS, VLM, LR, FS, MJ, TSN, A-AM completed the acquisition of data. MHD, NB performed the data analysis. All authors assisted with the interpretation. MHD and CY were the principal writers of the manuscript. All authors contributed to the drafting and revision of the final article. All authors approved the final submitted version of the manuscript.
Funding This project was funded by a Canadian Institutes of Health Research Knowledge Synthesis Grant (140995). MHD is funded by an Advancing Women’s Heart Health Initiative New Investigator Award supported by Health Canada and the Heart and Stroke Foundation of Canada (RES0033140). RJS is funded by a Canadian Institutes for Health Research Doctoral Research Award (146252). A-AM is funded by a Fonds de Recherche du Québec – Santé Doctoral Research Award (34399).
Competing interests None declared.
Patient consent Not required.
Provenance and peer review Not commissioned; externally peer reviewed.