Abstract
Physical activity has been inconsistently associated with risk of gestational diabetes mellitus in epidemiological studies, and questions remain about the strength and shape of the dose–response relationship between the two. We therefore conducted a systematic review and meta-analysis of cohort studies and randomized trials on physical activity and gestational diabetes mellitus. PubMed, Embase and Ovid databases were searched for cohort studies, and randomized controlled trials of physical activity and risk of gestational diabetes mellitus, up to August 5th 2015. Summary relative risks (RRs) were estimated using a random effects model. Twenty-five studies (26 publications) were included. For total physical activity the summary RR for high versus low activity was 0.62 (95 % CI 0.41–0.94, I2 = 0 %, n = 4) before pregnancy, and 0.66 (95 % CI 0.36–1.21, I2 = 0 %, n = 3) during pregnancy. For leisure-time physical activity the respective summary RRs for high versus low activity was 0.78 (95 % CI 0.61–1.00, I2 = 47 %, n = 8) before pregnancy, and it was 0.80 (95 % CI 0.64–1.00, I2 = 17 %, n = 17) during pregnancy. The summary RR for pre-pregnancy activity was 0.70 (95 % CI 0.49–1.01, I2 = 72.6 %, n = 3) per increment of 5 h/week and for activity during pregnancy was 0.98 (95 % CI 0.87–1.09, I2 = 0 %, n = 3) per 5 h/week. There was evidence of a nonlinear association between physical activity before pregnancy and the risk of gestational diabetes mellitus, pnonlinearity = 0.005, with a slightly steeper association at lower levels of activity although further reductions in risk were observed up to 10 h/week. There was also evidence of nonlinearity for physical activity in early pregnancy, pnonlinearity = 0.008, with no further reduction in risk above 8 h/week. There was some indication of inverse associations between walking (before and during pregnancy) and vigorous activity (before pregnancy) and the risk of gestational diabetes mellitus. This meta-analysis suggests that there is a significant inverse association between physical activity before pregnancy and in early pregnancy and the risk of gestational diabetes mellitus. Further studies are needed to clarify the association between specific types and intensities of activity and gestational diabetes mellitus.Electronic supplementary materialThe online version of this article (doi:10.1007/s10654-016-0176-0) contains supplementary material, which is available to authorized users.
Highlights
Gestational diabetes mellitus is an important cause of maternal and perinatal complications including preeclampsia, gestational hypertension, caesarean section, macrosomia, and stillbirths [1]
Out of the 7616 records which were identified by the literature search, 7501 were excluded based on the title and abstract, and 115 full text articles were assessed in detail as they reported on physical activity or risk factors and gestational diabetes mellitus in the title/abstract (Fig. 1)
Physical activity during pregnancy associated with a 36 % reduction in the relative risk of gestational diabetes, while the association for total physical activity during pregnancy was in the direction of reduced risk, but was not statistically significant, possibly due to few studies
Summary
Gestational diabetes mellitus is an important cause of maternal and perinatal complications including preeclampsia, gestational hypertension, caesarean section, macrosomia, and stillbirths [1]. There is still no international agreement about the definition of gestational diabetes mellitus [3]. The prevalence of gestational diabetes mellitus is increasing worldwide [4] parallel to the increase in prevalence of overweight and obesity among pregnant women. Overweight and obesity is the strongest risk factor for gestational diabetes mellitus with 2–3 and 5–6 fold increases in the relative risk (RR) compared to normal weight women [5, 6]. Some evidence suggests an increased risk even within the high-normal range of body mass index compared to the low-normal range [7, 8], similar to what is observed for type 2 diabetes [9]. Gestational diabetes and type 2 diabetes have many pathophysiological features in common
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