Assocition Between Endometrial Thickness And Pregnancy Outcome: A Meta-Analysis

Objective:Endometrial receptivity have been confirmed to be related to the recurrent spontaneous abortion and repeated implantation failure. Low endometrial receptivity may lead to lower embryo implantation, and higher rate of spontaneous abortion. And, endometrial receptivity can be reflected by endometrial thickness.To evaluate the clinical significance of the endometrial thickness for the pregnancy outcome, we performed a systemreview and meta-analysis.Methods:The electronic databases PubMed, Cochrane Library, Embase, CNKI, WANFANG DATA were searched until December 2015 for articles which described EMT and pregnancy outcome. The screening, quality evaluation, heterogeneity of the literature of related analysis and extract the cohort study of the basic information. By using the Mantel Haenszel-fixed effects model combined the ORs and their 95%CI analyze the correlation between the endometrial thickness and the pregnancy outcome. Stata 12.0 was used to analyze the data.Results:A total of 13 case-control studies were eligible for the meta-analysis, of which six studies with 14568 cases involved to ongoing pregnancy rate, three studies with 5073 cases involved to miscarriage rate,11 studies with 12120 cases were involved in the clinical pregnancy rate, the prospective study 2 studies,6 retrospective studies. A thin endometrium (≤7 mm) was observed in only 2.0% of the reported cases (464/23005), and endometrial thickness> 14mm was observed in 17.22% of the reported cases (3962/23005). In these cases a trend towards lower miscarriage rate for women with thinner endometrial thickness, while these differences did not reach statistical significance [(OR=0.94,95%CI:0.29-3.06), P=0.91]、[(OR=0.99, 95% CI:0.71-1.38), P=0.95].The probability of ongoing pregnancy and clinical pregnancy for an EMT≤7mm was significantly lower compared with cases with EMT7-14mm, and EMT7-14mm was significantly lower compared with cases with EMT> 14mm (OR=0.46,95%CI:0.34-0.62)、(OR=0.52, 95%CI:0.48-0.57)、(OR=0.34,95%CI:0.25-0.47)、(OR=0.88,95%CI: 0.80-0.98).Conclusions:There was no significant correlation between endometrial thickness and miscarriage rate when the cut-offs are 7mm and 14mm. A thin endometrium is related to a lower chance of ongoing pregnancy and clinical pregnancy. Further research is needed to investigate the real independent significance of EMT in pregnancy outcome.