Abstract: We included 11 RCTs (3215 women). The quality of the evidence ranged from very low to low. The main limitations were risk of bias (associated with poor reporting of allocation concealment and other methods) and imprecision for the primary outcome of live birth rate. Live birth rates: Seminal plasma application made little or no difference in live birth rates (RR 1.10, 95% CI 0.86 to 1.43; 948 participants; 3 studies; I2 = 0%). Low-quality evidence suggested that if the live birth rate following standard ART was 19%, it would be between 16% and 27% with seminal plasma application. Miscarriage rate: Seminal plasma application made little or no difference in miscarriage rates (RR 1.01, 95% CI 0.57 to 1.79; 1209 participants; 4 studies; I2 = 0%). Low-quality evidence suggested that if the miscarriage rate following standard ART was 3.7%, the miscarriage rate following seminal plasma application would be between 2.1% and 6.6%. Live birth or ongoing pregnancy rates: Seminal plasma application made little or no difference in live birth or ongoing pregnancy rates (RR 1.19, 95% CI 0.95 to 1.49; 1178 participants; 4 studies; I2 = 4%, low-quality evidence). The evidence suggested that if the live birth or ongoing pregnancy rate following standard ART was 19.5%, it would be between 18.5% and 29% with seminal plasma application. Clinical pregnancy rates: We are uncertain whether seminal plasma application increases clinical pregnancy rates (RR 1.15, 95% CI 1.01 to 1.31; 2768 participants; 10 studies; I2 = 0%). Very low-quality evidence suggested that if the clinical pregnancy rate following standard ART was 22.0%, it would be between 22.2% and 28.8% with seminal plasma application. This finding should be regarded with caution, as a post hoc sensitivity analysis restricted to studies at overall low risk of bias did not find a significant difference between the groups (RR 1.06, 95% CI 0.81 to 1.39; 547 participants; 3 studies; I2 = 0%). Multiple pregnancy rate: Seminal plasma application may make little or no difference to multiple pregnancy rates (RR 1.11, 95% CI 0.76 to 1.64; 1642 participants; 5 studies; I2 = 9%). Low-quality evidence suggested that if the multiple pregnancy rate following standard ART was 7%, the multiple pregnancy rate following seminal plasma application would be between 5% and 11.4%. Ectopic pregnancy: There was insufficient evidence to determine whether seminal plasma application influenced the risk of ectopic pregnancy (RR 1.59, 95% CI 0.20 to 12.78, 1521 participants; 5 studies; I2 = 0%) . Infectious complications or other adverse events: No data were available on these outcomes In women undergoing ART, there was insufficient evidence to determine whether there was a difference between the seminal plasma and the standard ART group in rates of live birth (low-quality evidence) or miscarriage (low-quality evidence). There was low-quality evidence suggesting little or no difference between the groups in rates of live birth or ongoing pregnancy (composite outcome). We found low-quality evidence that seminal plasma application may be associated with more clinical pregnancies than standard ART. There was low-quality evidence suggesting little or no difference between the groups in rates of multiple pregnancy. There was insufficient evidence to reach any conclusions about the risk of ectopic pregnancy, and no data were available on infectious complications or other adverse events. We conclude that seminal plasma application is worth further investigation, focusing on live birth and miscarriage rates.

Plain-language summary: This Cochrane review included 11 randomised controlled trials, in which women were randomly allocated to receive seminal plasma or not. These trials included a total of 3215 women undergoing ART. The evidence is current to October 2017. We found no clear evidence to suggest whether seminal plasma application influences rates of live birth or miscarriage in women undergoing ART. However, we found low-quality evidence suggesting that seminal plasma application may possibly lead to more clinical pregnancies than standard ART. There was low-quality evidence suggesting little or no difference between the groups in rates of multiple pregnancy. There was insufficient evidence to reach any conclusions about the risk of ectopic pregnancy (pregnancy in which the embryo attaches outside the womb), and no data were available on infectious complications or other adverse events. We conclude that seminal plasma application is worth further investigation focusing on live birth and miscarriage rates. The quality of evidence ranged from very low to low.The main limitations were risk of bias (associated with poor reporting of study methods) and lack of data for the primary outcome of live birth rate.