Environmental exposure in the etiology of infantile hypertrophic pyloric stenosis: a systematic review and meta-analysis.

PURPOSE: To investigate the occupational and environmental factors in the etiology of infantile hypertrophic pyloric stenosis (IHPS). METHODS: Protocol was drafted according to the PRISMA guidelines and registered on PROSPERO (CRD42020152460). A search for a combination of terms related to IHPS, fetus and neonates, and environmental exposure was performed for studies published between 2000 and 2020 in the EMBASE, Pubmed, and MEDLINE databases. RESULTS: Overall, 2203 abstracts were identified and 829 were screened. The full text of the selected articles (N = 98) was assessed for eligibility. Fifteen studies were included in quantitative synthesis. IHPS risk was significantly lower in black and Hispanic mothers than in white mothers [OR 0.47 (95% CI 0.44-0.51, p < 0.001), OR 0.85 (95% CI 0.77-0.94, p = 0.002), respectively]. Lower maternal education level and maternal smoking were risk factor for IHPS. We further observed a non-significant association between maternal folic acid usage and IHPS risk. Data were insufficient to evaluate occupational exposure. CONCLUSION: This review provides an understanding of the role of environmental exposures in IHPS etiology. Lower maternal educational level, maternal smoking, and white ethnicity are associated with a significantly increased risk of IHPS, while folic acid use seems non-significantly associated with IHPS risk. LEVEL OF EVIDENCE: III.