Effects of antenatal exercise in overweight and obese pregnant women on maternal and perinatal outcomes: a randomised controlled trial SN Seneviratne, a,b Y Jiang, c JGB Derraik, a LME McCowan, b,d GK Parry, d JB Biggs, a S Craigie, a S Gusso, a G Peres, a RO Rodrigues, a A Ekeroma, d WS Cutfield, a,b PL Hofman a,b a Liggins Institute, University of Auckland, Auckland, New Zealand b Gravida: National Centre for Growth and Development, Auckland, New Zealand c Department of Statistics, University of Auckland, Auckland, New Zealand d Department of Obstetrics and Gynaecology, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand Correspondence: PL Hofman, Liggins Institute, University of Auckland, Private Bag 92019, Auckland, New Zealand. Email p.hofman@auckland.ac.nz Accepted 13 September 2015. Published online 6 November 2015. Objective To assess whether antenatal exercise in overweight/obese women would improve maternal and perinatal outcomes. Design Two-arm parallel randomised controlled trial. Setting Home-based intervention in Auckland, New Zealand. Population and sample Pregnant women with body mass index ≥25 kg/m 2 . Methods Participants were randomised to a 16-week moderate- intensity stationary cycling programme from 20 weeks of gestation, or to a control group with no exercise intervention. Main outcome measures Primary outcome was offspring birthweight. Perinatal and maternal outcomes were assessed, with the latter including weight gain, aerobic fitness, quality of life, pregnancy outcomes, and postnatal body composition. Exercise compliance was recorded with heart rate monitors. Results Seventy-five participants were randomised in the study (intervention 38, control 37). Offspring birthweight (adjusted mean difference 104 g; P = 0.35) and perinatal outcomes were similar between groups. Aerobic fitness improved in the intervention group compared with controls (48.0-second improvement in test time to target heart rate; P = 0.019). There was no difference in weight gain, quality of life, pregnancy outcomes or postnatal maternal body composition between groups. However, compliance with exercise protocol was poor, with an average of 33% of exercise sessions completed. Sensitivity analyses showed that greater compliance was associated with improved fitness (increased test time (P = 0.002), greater VO 2 peak (P = 0.015), and lower resting heart rate (P = 0.014)), reduced postnatal adiposity (reduced fat mass (P = 0.007) and body mass index (P = 0.035)) and better physical quality of life (P = 0.034). Conclusions Maternal non-weight-bearing moderate-intensity exercise in pregnancy improved fitness but did not affect birthweight or clinical outcomes. Keywords Antenatal exercise, body composition, obesity, pregnancy, quality of life. Tweetable abstract Moderate-intensity exercise in overweight/ obese pregnant women improved fitness but had no clinical effects. Please cite this paper as: Seneviratne SN, Jiang Y, Derraik JGB, McCowan LME, Parry GK, Biggs JB, Craigie S, Gusso S, Peres G, Rodrigues RO, Ekeroma A, Cutfield WS, Hofman PL. Effects of antenatal exercise in overweight and obese pregnant women on maternal and perinatal outcomes: a randomised controlled trial. BJOG 2016;123:588–597. Introduction There has been a global increase in rates of overweight and obesity among women of reproductive age. The number of women entering pregnancy in an overweight or obese state has nearly doubled over the last three decades, now affecting more than a third of pregnancies in some nations. 1–4 Overweight and obesity are associated with many preg- nancy complications, including a two- to three-fold increase in the risk of gestational diabetes, pregnancy- induced hypertension and pre-eclampsia, as well as increased risk of caesarean section, induction of labour, and longer hospital stay. 5 Importantly, offspring born to overweight/obese women tend to be heavier and fatter at birth, and also are at higher risk of perinatal complica- 588 ª 2015 Royal College of Obstetricians and Gynaecologists DOI: 10.1111/1471-0528.13738 www.bjog.org General obstetrics