Gestational diabetes mellitus (GDM), defined as 'glucose intolerance and insulin resistance first detected during pregnancy. In more than 50% of cases, GDM may progress to type 2 diabetes mellitus, hypertension and cardiovascular diseases within 5–15 years after pregnancy. Additionally, GDM is associated with several maternal and perinatal complications such as hypertensive disorders of pregnancy (HDP), which include gestational hypertension (GH), pre-eclampsia and eclampsia, affecting 10% of pregnancies. Likewise, HDP are associated with higher life-long cardiovascular risk. Otherwise, fetal overgrowth or macrosomia is one of the fetal complications that occur in up to 45% of GDM pregnancies. These babies have an increased risk of overweight, obesity and type 2 diabetes later in life.

Several studies have suggested that exercise is an effective strategy for preventing and treating diabetes and hypertension in the general population by reducing some of the mechanisms involved in inflammation, oxidative stress and endothelial dysfunction, all of which are pathophysiological mechanisms involved in the genesis of HDP and GDM. That, in turn, is associated with obesity and physical inactivity. However, the evidence about the effectiveness of exercise in avoiding the development of both disorders during pregnancy is still not consistent. Some reviews reported that physical activity (PA) programmes produced reductions in the prevalence of GDM.
Umbrella review carried by Martínez-Vizcaíno V, Sanabria-Martínez G, Fernández-Rodríguez R et al aimed to provide a comprehensive overview of the effect of exercise interventions during pregnancy on GDM and HDP. PubMed, EMBASE, Web of Science, Cochrane database of systematic reviews, Epistemonikos, SPORTDiscus, Clinicaltrials.gov, and PROSPERO register were searched from the database inception until August 2021. Random-effects model was used to calculate relative risk with 95% confidence interval in the updated meta-analysis. The reference category was the groups that received usual prenatal care. AMSTAR 2 and the Cochrane Collaboration tool were used to assess the quality and GRADE approach was used to assess the overall certainly of evidence.

Twenty-three systematic reviews and meta-analyses; and 63 RCTs were included. Single exercise interventions reduced the incidence of GDM and HDP in most systematic reviews and meta-analyses.
Moreover, exercise interventions during pregnancy decrease the incidence of developing GDM and GH, particularly when they are supervised, have a low to moderate intensity level, and are initiated during the first trimester of pregnancy.
Based on 21 systematic reviews and meta-analyses, and 54 RCTs, authors found that exercise interventions were more effective than standard prenatal care in reducing the incidence of GDM and GH by 39% and 47%, respectively. In contrast, subgroup analyses showed no effect of exercise on the incidence of HDP in overweight and obese pregnant women or when sessions lasted less than 45 minutes.
Meanwhile, study data suggest that exercise is more effective in reducing the GDM and HDP incidence when initiated in the first trimester of pregnancy, under supervision and with light to moderate intensity, whereas exercise only reduced the incidence of preeclampsia when pregnant women started exercise in the first trimester of pregnancy. Trial sequence analysis indicates that additional studies are needed to elucidate the effect of PA interventions on pre-eclampsia incidence.
In summary, the current evidence supports that exercise has a beneficial effect on the incidence of GDM and GH in non– overweight or obese pregnant women. Furthermore, these benefits are greater when exercise interventions are supervised, have a low to moderate intensity level, and are initiated during the first trimester of pregnancy.
Nevertheless, more high-quality intervention studies are needed to accurately evaluate the safety and benefits of exercise programmes for specific pregnant populations, such as women with overweight and obesity, and whether higher intensity exercise interventions result in greater benefits in these groups. In addition, according to this data, to achieve greater benefits, the core of recommendation for clinicians is that exercise should be supervised, initiated in the first trimester of pregnancy, and lasting more than 45 minutes per session. However, few studies have reported a reduction in HDP among women with overweight and obesity. More studies are needed to test the effectiveness of exercise interventions to reduce the incidence of pre-eclampsia in pregnant women with excess weight.
Source: Martínez-Vizcaíno V, Sanabria-Martínez G, Fernández-Rodríguez R, Cavero-Redondo I, Pascual-Morena C, Álvarez-Bueno C, et al. Exercise during pregnancy for preventing gestational diabetes mellitus and hypertensive disorders: An umbrella review of randomised controlled trials and an updated meta-analysis. BJOG. 2022;00:1–12.
https://doi.org/10.1111/1471-0528.17304