SHANGHAI, April 20 (Reuters) - China kept its benchmark lending rate for corporate and household loans steady for the 12th straight month at its April fixing on Tuesday, matching market expectations. The one-year loan prime rate (LPR) was kept at 3.85%. The five-year LPR remained at 4.65%. Twenty-seven traders and analysts of 30 participants in a Reuters poll this week predicted no change in either rate. Most new and outstanding loans in China are based on the one-year LPR. The five-year rate influences the pricing of mortgages.