Impact of previous Caesarean section on reproductive outcomes after assisted reproductive technology: systematic review and meta-analyses.

This meta-analysis investigated whether a previous Caesarean section has an impact on the outcomes of treatment with assisted reproductive technology (ART). PubMed, Embase, Cochrane Library, Web of Science and Google Scholar were searched. Clinical trials published in English up to May 2020 were included. Seven studies performed between 2016 and 2020 met all the inclusion criteria. It was found that previous Caesarean section leads to significantly decreased clinical pregnancy rate (CPR) (risk ratio [RR] 0.86; 95% confidence interval [CI], 0.81, 0.92; P < 0.00001) and live birth rate (LBR) (RR 0.80; 95% CI 0.73, 0.86; P < 0.00001). Caesarean section increased the miscarriage rate (RR 1.39; 95% CI 1.18, 1.64; P < 0.0001), and difficult transfer (RR 8.23; 95% CI 4.63, 14.65; P < 0.00001) after ART compared with women who had previous vaginal delivery. The combined results also showed similar endometrial thickness, number of oocytes retrieved, implantation rate, ectopic pregnancy rate, preterm birth and stillbirth between women with previous Caesarean section and women with previous vaginal delivery. In conclusion, Caesarean sections have a detrimental effect on CPR and LBR, and increase the risk of miscarriage and difficult transfer. The indications for Caesarean section should be strictly controlled, and full consultation should be provided to pregnant women. Further studies with stratification analysis of twin and single pregnancies are needed to evaluate the impact of Caesarean section.