The authors concluded that regular aerobic exercise training by active, low risk and previously sedentary pregnant women had a favourable and beneficial effect on maternal weight gain in pregnancy. The authors’ conclusions appear overstated given the differences between study participants. Limitations in the reporting of methods and data mean that the conclusions may not be reliable.

To assess the effect of aerobic exercise training on maternal weight in pregnancy.

PubMed was searched to May 2012 for relevant peer-reviewed articles published in English. Search terms were reported. Reference lists of identified articles were examined.

Eligible studies were randomised controlled trials (RCTs) that assessed the effect on maternal weight of aerobic training of moderate intensity compared to a sedentary control. Moderate intensity of aerobic training was defined as 40 to 60 VO₂max (maximal oxygen consumption) or 60% to 79% HRmax (maximum heart rate) at least three times per week. The primary outcome of interest was maternal body weight.

Studies recruited participants at various stages of pregnancy. Only one study reported including normal weight and obese participants. Pre-exercise weight was measured at recruitment and post-training weight was measured at the commencement of labour.

The authors did not state how many reviewers selected studies for inclusion.

It appeared that the authors considered some quality assessment criteria including enrolment, therapy allocation and reasons for drop-out.

It appeared that two independent reviewers assessed study quality. Disagreements were resolved through consensus.

Data on maternal body weight were extracted independently by two reviewers using a standard form. Data were used to calculate mean differences in kilograms (kg) and standard deviations (SD).

Data were combined in a meta-analysis. There was no apparent assessment of statistical heterogeneity.

Eleven RCTs (1,177 participants, range 39 to 363) were included in the review. The RCTs were described as “reasonable to good quality”.

Participants in aerobic exercise groups had significantly less maternal weight gain at labour than those in control groups (Exercise 11.31kg SD 7.44; Control 14.42kg SD 6.60; p<0.05).

The regular practice of aerobic exercise training by active, low risk and previously sedentary pregnant women had a favourable and beneficial effect on maternal weight gain in pregnancy.

The review question was clear with broadly defined inclusion criteria. Only one database was searched and inclusion was limited to articles in English so some relevant articles may have been missed. The authors reported that they assessed study quality but did not report the results so the reliability of the evidence was unclear. Methods to reduce reviewer error and bias (two independent reviewers) were used for the assessment of study quality and extraction of data; it was unclear whether the authors used similar methods during study selection.

Studies were combined in a meta-analysis but few details of the methods were provided so it was unclear whether pooling data was appropriate. The authors reported that there were clinical differences between trials in participant age, physical characteristics, diet, daily energy intake and differences in recruitment gestational age so a narrative synthesis might have been more appropriate. The authors reported that there was no evidence of statistical heterogeneity but did not provide details. Few study details were reported so it was not possible to determine the generalisability of the results. The authors commented on the failure of the studies to distinguish between normal, overweight and obese pregnant women which could affect the results.

The authors’ conclusions appear overstated given the differences between participants in the included studies and lack of detail about some participant characteristics. Adverse effects and safety were not assessed but the implications for practice stated that aerobic exercise was safe. These issues and limitations in the reporting of methods and data mean that the conclusions may not be reliable.

Practice: The authors stated that aerobic exercise was safe and beneficial in the absence of medical and obstetric complications in pregnancy.

Research: The authors stated that further RCTs were needed to evaluate the effect of aerobic exercise training on maternal weight gain in pregnancy.

Not stated.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.