Association of Estrogen Receptor 1 Genetic Polymorphisms with Recurrent Spontaneous Abortion Risk

Background: Estrogen is one of the most important reproductive steroidal hormones and plays a critical role in the maintenance of pregnancy, and its function is mediated by estrogen receptor 1 (ESR1). The polymorphisms of ESR1 were involved in recurrent spontaneous abortion (RSA); however, the association between ESRJ polymorphisms and RSA remains controversial. The present meta-analysis was aimed to clarify the association between ESRJ PvuII (-397C/T, rs2234693) and Xba (-351A/G, rs9340799) polymorphisms and the risk of RSA. Methods: All the included articles were retrieved from PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, and Wanfang Med Online Database up to January 3, 2018. Data were processed in the Stata 12.0 software. The odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using fixed-effects models (FEM)/random-effects models (REM). Results: Seven case-control studies with 836 cases and 1164 controls were included in the study. Generally, the ESR1 polymorphisms were not associated with RSA in any of the genetic analysis models. However, it was found that as rs9340799 polymorphism was related to increased risk of RSA in non-Asian group in the homozygous genetic model (OR = 2.40, 95% CI = 1.05-5.50, P = 0.039). Moreover, in Asian group, rs9340799 polymorphism was found to be related to decreased RSA risk in both the heterozygous model (OR = 0.53, 95% CI = 0.33-0.85, P = 0.009) and the dominant genetic model (OR = 0.55, 95% CI = 0.30-0.98, P = 0.042). Conclusions: Generally, there was no significant association between the polymorphisms of ESR1 and the risk of RSA. However, subgroup analysis indicated that ESR1 rs9340799 polymorphism was related to increased RSA risk in the non-Asian group while associated with decreased RSA risk in Asian group.