Risk factors of gestational diabetes mellitus recurrence: a meta-analysis

The literature regarding risk factors for gestational diabetes mellitus (GDM) recurrence is inconsistent. We aimed to assess the effect sizes of risk factors of GDM recurrence. We searched electronic databases (1970-2015) and bibliographies for studies that included women with GDM (index pregnancy) who had a consecutive birth. We compared the risk factors among women with and without GDM recurrence. Differences in variables measured on a continuous scale were estimated using the weighted mean difference (WMD). The standardized mean difference (SMD) was used to rate the pooled effects. For categorical variables, the pooled odds ratio was estimated. Cochran's Q test of heterogeneity was used to choose the model for estimating the pooled effects. Fourteen cross-sectional cohort studies (63 % with sample size ≥100) were considered. Women with GDM recurrence were older (by 1.32 years; P < 0.0001), heavier (by 1.82 BMI; P = 0.013), had higher 100-g oral glucose tolerance test (OGTT) levels (Fasting: by 8.42 mg/dl, 1-h: by 13.0 mg/dl, 2-h: by 18.2 mg/dl, 3-h: by 11.3 mg/dl; P < 0.0001 for all) and higher weight gain between pregnancies (by 3.24 kg; P = 0.012). The SMD effect sizes were relatively small (between 0.3 and 0.4), but weight gain between pregnancies had a medium-large effect size (SMD = 0.8). Insulin use, multiparity, and fetal macrosomia were all associated with GDM recurrence (OR 6.3 [95 % CI 3.9-10.2], OR 1.88 [95 % CI 1.09-3.24] and OR 1.63 [95 % CI 1.25-2.13], respectively). GDM recurrence is multifactorial. Stronger risk factors include insulin use, BMI, multiparity, macrosomia, and weight gain between pregnancies.