Methods	Randomised controlled trial, set in Hospital de Fuen-labrada, Madrid, Spain
Participants	80 women randomised. Inclusion criteria: healthy pregnant women (age, 23-38 years), had uncomplicated, singleton pregnancies Exclusion criteria: any type of absolute obstetric contraindication to aerobic exercise during pregnancy, which included other contraindications that the authors considered to have a relevant influence on maternal perception of health: significant heart disease, restrictive lung disease, incompetent cervix/cerclage, multiple gestation, risk of premature labour, pre-eclampsia/pregnancy-induced hypertension, thrombophlebitis, recent pulmonary embolism (last 5 years), acquired infectious disease, retarded intrauterine development, serious blood disease, and/or absence of prenatal care
Interventions	Intervention group: (40 randomised) moderate physical activity, included a total of 35- to 45-minute weekly sessions 3 days each week from the start of the pregnancy (weeks 6-9) to the end of the 3rd trimester (weeks 38-39), an average of 85 training sessions, exercise intensity was light-to-moderate. Exercise was supervised by a fitness specialist and was in groups of 10-12 women Control group: (40 randomised) routine care.
Outcomes	Weight gain, caesarean, birthweight < 4000 gm, birthweight > 4000 gm
Notes
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomly assigned by use of a random number table.
Allocation concealment (selection bias)	Unclear risk	Not described.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Not mentioned. It would be difficult to blind women and staff to this type of intervention. It is not clear how lack of blinding would impact on the outcomes measured
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	80 women were randomised and 67 were analysed; 34 in the exercise group, 33 in the control group. Reason of discontinued were similar in both groups
Selective reporting (reporting bias)	Unclear risk	Assessment from published study report.
Other bias	Unclear risk	No between-group differences regarding potential confounding variables (such as occupational activities, standing, smoking habits, alcohol intake). Parity was not balanced between groups; the exercise group had a higher percentage of nulliparous women (76.5%) than the control group (36.4%)