Clubfoot Etiology: A Meta-Analysis and Systematic Review of Observational and Randomized Trials

Background:Clubfoot is a common congenital anomaly with multiple potential risk factors. Identification of modifiable risk factors may minimize future incidence of clubfoot. The aim of this meta-analysis was to systematically review and analyze the best clinical evidence regarding risk factors associated with clubfoot.Methods:Medline, Embase, and Cochrane databases were systematically searched from 1967 to May 11, 2016 for studies reporting risk factors for clubfoot. Randomized trials and observational studies were eligible for inclusion, and assessed in duplicate. Study quality was assessed with the Newcastle-Ottawa Scale or Cochrane risk of bias tool; low quality studies were excluded, all randomized trials were included. Two reviewers extracted data independently. This meta-analysis was conducted in accordance with PRISMA guidelines. Pooled effect estimates for the odds of clubfoot were calculated using random or fixed-effects models based on heterogeneity.Results:Forty-two studies (28 case-control, 10 cohort, 4 randomized trials) comprising 31,844 clubfoot cases and 6,604,013 controls were included. Risk factors associated with increased odds of clubfoot included maternal smoking [odds ratio (OR)=1.65; 95% confidence interval (CI), 1.54-1.78], paternal smoking (OR=1.72; 95% CI, 1.05-2.84), maternal body mass index >30 (OR=1.46; 95% CI, 1.29-1.65), family history (OR=7.80; 95% CI, 4.04-15.04), amniocentesis (OR=2.08; 95% CI, 1.34-3.21), selective serotonin reuptake inhibitor exposure (OR=1.78; 95% CI, 1.34-2.37) maternal single status (OR=1.17; 95% CI, 1.11-1.23), gestational diabetes (OR=1.40; 95% CI, 1.13-1.72), nulliparity (OR=1.32; 95% CI, 1.19-1.45), male sex (OR=1.68; 95% CI, 1.48-1.94), and aboriginal Australian race (OR=2.35; 95% CI, 1.63-3.38).Conclusions:Smoking, maternal obesity, family history, amniocentesis, and some selective serotonin reuptake inhibitor exposures are the most clinically relevant exposures associated with increased odds of clubfoot, with family history representing the greatest risk. Recognition of modifiable risk factors may help in counseling patients, and minimizing clubfoot incidence.Level of Evidence:Level II.