The increasing prevalence of overweight and obesity worldwide represents a complex and chronic public health challenge. Recent estimates highlight the burden, with only 40% of the adult population in Australia and the United Kingdom and 30% in the United States within a healthy weight range. Trends demonstrate that overweight and obesity are affecting the population at a younger age, with the most rapid rate of weight gain reported between 20–40 years of age. Women are at the highest risk, with a higher conversion to overweight and obesity compared with men on cross-sectional analysis.

stracing legIncreased weight in reproductive aged women is associated with cardiometabolic (glucose intolerance, dyslipidaemia, Type 2 Diabetes [T2DM] risk factors for Cardiovascular Disease [CVD]), reproductive (anovulation, Polycystic Ovary Syndrome [PCOS], infertility) and psychological (Depression, Quality of Life [QoL]) health risks. Pregnancy exacerbates obesity risk, with the majority of women exceeding international Institute of Medicine (IOM) recommendations for gestational weight gain (GWG). Excessive GWG increases postpartum weight retention, and in conjunction with progressive weight gain, drives long-term obesity risk independent of pre-pregnancy body mass index (BMI). With modest weight gain from a healthy BMI contributing to risk of preventable disease, preventive strategies are now a key international priority and lifestyle modification is the first line approach. Physical activity is an important lifestyle modification component, with protective health benefits, as well as a clear role in weight gain prevention, independent of diet. This review evaluates current evidence for the beneficial role of physical activity in relation to preconception, pregnancy and postpartum health. Research utilizing physical activity and/or exercise as a stand-alone therapy is presented to evaluate its efficacy independent to other lifestyle therapy components.

The Role of Physical Activity in Preconception Health

Despite the barriers in engaging otherwise healthy women prior to pregnancy for preconception healthcare, previous studies demonstrate PA intention and participation can be improved following lifestyle counselling of 2–6 sessions. PA interventions are lacking however, with two recent systematic reviews finding no previous studies investigating PA for improved health outcomes in the preconception period, even in higher riskoverweight and obese populations. Given preconception PA is a strong predictor of continued PA during pregnancy, establishment of regular PA prior to pregnancy should be an important component of healthy pregnancy planning.

Infertility and Assisted Reproduction

Overweight and obesity impair female fertility and reduce the chance of spontaneous and assisted conception. Weight management, including regular PA, is important in preventing and treating infertility. Evidence suggests that moderate regular PA positively influences fertility and Assisted Reproductive Therapy (ART) outcomes. A recent study has shown that in obese women undergoing IVF (n ¼ 216), regular PA is associated with higher success rates (39% versus 16% in sedentary women) and improved live birth rates (24.4% versus 7.4%), with comparable results demonstrated elsewhere. However, the evidence for the effects of vigorous exercise on fertility and/or ART success is equivocal. A 2002 study of 26,955 women, found that each hour per week of vigorous activity was associated with a 7% lower relative risk of ovulatory infertility (5% on adjustment of BMI). Yet, a population based health survey in 3887 women under 45 years of age reported an association between vigorous (exercising daily or to exhaustion) exercise and subfertility. However no associations were reported with lower intensity PA. Similarly, a prospective cohort study of 2232 women reported that at least 4 hours of higher intensity PA for a year or more prior to IVF was associatedwith a 5 fold increase in cycle cancellation, a 2.5 fold increase in failed implantation, a 30% lower chance of successful pregnancy and a 50% reduction in live births compared with women who reported no regular PA.

Polycystic Ovary Syndrome

Recognized as the leading cause of anovulatory infertility, Polycystic Ovary Syndrome (PCOS) affects up to 12–18% of reproductive aged women. PCOS is a multifaceted disorder with metabolic (insulin resistance [IR], T2DM and CVD risk factors), reproductive (hyperandrogenism and oligoovulation) and psychological sequelae. Varying phenotypes of PCOS increase complexity, complicate the path to diagnosis and together with clinical factors, increase anxiety and depression and reduce QoL. Diagnosis requires at least two of clinical or biochemical hyperandrogenism, anovulatory menstrual dysfunction and polycystic ovaries on ultrasound, in the absence of secondary causes. Although not required for diagnosis, insulin resistance (IR) and intrinsic insulin signaling defects are strongly implicated in the etiology of PCOS and underpin both reproductive and cardio-metabolic disturbances. Obesity, present in 40–88% of women with PCOS, worsens IR and exacerbates themetabolic, reproductive and psychological features of PCOS. Lifestyle change is recommended as a first line treatment strategy for PCOS and physical activity is an important component, with a single exercise bout enhancing whole body glucose disposal and continued, regular exercise reducing T2DM risk in high risk, glucose intolerant groups.polycystic ovaries

In studies addressing exercise as an independent therapy in PCOS, themost consistent improvements appear to be to IR with either neutral or small changes noted in other cardio-metabolic parameters including weight, body fat, waist-to-hip ratio, lipids and blood pressure. When measured directly with the gold standard euglycaemic clamp, intensified exercise training improved IR by 16% in overweight and obese women with PCOS, yet in BMI matched non-PCOS controls a 23% improvement was noted, emphasizing the intrinsic IR defects of the disorder. Other studies using indirect measures of IR havereported a 9–30% improvement in fasting insulin as well as in the IR indices, HOMA-IR and AUCINS, following exercise.

All previous studies have reported improvements with 12weeks of exercise intervention, independent of the type or frequency of exercise, with 3–5 sessions per week of both moderate (40–70% VO2 max) and higher intensity interval training (95–100% VO2 max), shown to be effective. Reported changes to BMI with exercise are 1.5kg/m2 (-0.85 to -2.1kg/m2) within three to six months of exercise. A higher percentage of weight loss (10.6%) has been reported in PCOSwhen diet is combined with exercise, confirming that a larger energy deficit is more likely to lead to weight loss in line with general populations.

Evidence for the effect of exercise on fertility in overweight and obese women with PCOS is limited, with three studies identified in a systematic review. Improved menstrual and/or ovulation frequency was reported in 60% of women following a moderate intensity exercise intervention three times per week for 45 minutes for 12 weeks compared with minimal therapy. However, menses frequency during the study period andminimal therapy group results were not provided so these findings should be interpreted with caution. Similar findings using the same exercise intervention (3 moderate intensity sessions of 30 minutes per week) but with a 24 week duration were also reported compared with a low-calorie, high-protein diet. Further research is required to confirm whether exercise is superior to dietary intervention for improved ovulation and menses regularity in PCOS. Continuity of exercise is important, with cessation reversingmetabolic improvements and weight benefits. Research is limited by small, lowquality studies and further research is required to optimize exercise therapies for PCOS including frequency, duration and intensity of PA for the differing phenotypic profiles of PCOS. With a lack of PCOS specific recommendations, all women should be encouraged to exercise regularly, as per population guidelines for PA.

Weight Gain Prevention, Weight Loss, and Prevention of Weight Regain

It is generally accepted that exercise, as an independent therapy without change to caloric intake, is insufficient to induce significant weight loss beyond the definitions for weight maintenance (i.e. 3% of baseline weight). Because of the excessive amount of exercise required to induce even modest weight loss, dietary restriction is more effective, achievable and practical for general populations. However, when exercise is combined with dietary restriction as part of a lifestyle intervention to induceweight loss, the combination of both on the daily energy deficit potentiates weight loss compared with dietary intervention alone.weight loss regain

Yet, regular PA is important for weight gain prevention, with those achieving the higher end of the recommended activity range less likely to gain weight long-term than sedentary individuals. Current recommendations for prevention of weight gain include at least 60 minutes per day of moderate PA or the equivalent volume of more vigorous PA. Modest changes in weight of between 2–3kg are noted when PA level is higher at 225–420 minutes/week; equivalent to 45 minutes per day. There is also a role of regular exercise in the prevention of weight regain followingweight loss. Those maintainingweight for at least 5 years in theNationalWeight Control Registry report high levels of PA (1 hour/day) aswell as a low-calorie and lowfat diet, regular self-monitoring and consistent eating patterns. A prospective study assessing weight regain in reproductive aged women found 80% of women regained above 30% of their initial weight loss, confirming the difficulties of weight maintenance following weight loss. However, PA at least 30 minutes/day reduced the likelihood of weight regain compared with remaining sedentary (OR 0.69, 95% CI 0.53, 0.89). A dose–response effect was also reported, with less weight regain in those undertaking more vigorous exercise, than in those who walked (-3.26kg vs -1.69kg).

Well-Being, Anxiety, Depression, and Quality of Life

The established link between regular PA and psychological well-being demonstrate its importance across several health outcomes including mood, self-efficacy, symptoms of anxiety and depression and health related QoL. The impact of regular PA on the psychological health of young women is particularly important. An extensive population based study in 20,000 men and women, reported a higher prevalence of anxiety, depression and anxious depression in women than in men aged between 20–35 years. However, a lower prevalence of all three conditionswas reported in women who maintained at least 60 minutes/week of self-reported moderate intensity PA compared with sedentary women. Further, compared with diagnosed depression in 22.4% of women classified as sedentary (<5,000 steps/day), the prevalence was halved (9.3%) in women reporting 7,500 steps/day. Health related quality of life (HQoL) is positively associated with regular PA. A systematic review of 11 interventional studies (1406 healthy male and female participants), reported significantly improved psychological and physical HqoL with 3–6 months of light or moderate intensity PA compared with no treatment. In infertile populations, where psychological implications are higher, regular PA improves depression, body image distress and HQoL. Better psychological health outcomes occur with a diverse range of PA patterns including self-reported leisure time activity and structured exercise interventions of varying

frequency, duration and intensity. There is some evidence to support a dose response relationship, with higher levels of leisure time PA of moderate or vigorous intensity or a combination associated with better measures ofwell-being, lower anxiety symptoms, lower depression and higher HQoL scores, than lower intensity PA levels.