Patterns of sexual behavior are built around the working day, and sexual intercourse tends to be favored at bedtime rather than at other times. It is at intercourse that perineal organisms (organisms present between the anus and the vulva) may be physically displaced into the upper urethra and bladder, and it is this activity that may help to inoculate organisms into the urinary bladder. After the large evening meal, and perhaps fruit or dessert and some wine or other alcoholic beverage, there may be energy sources in the urine to feed the organisms. Sex is followed by sleep and an interval of reduced fluid intake during which time the organisms are effectively incubated in the bladder. The organisms are neither diluted nor displaced. It is interesting that the common advice given to women is to empty your bladder before sex and then to empty again immediately afterwards. That may seem reasonable, but nature cannot empty a bladder that has just been emptied. It is much better for women to empty the bladder before sex and then drink a large glass or two of water afterwards. This will help to dilute the urine and create an environment less favorable for the growth of organisms. When the bladder fills, awake to urinate, and then drink again. This may be continued for some hours until the risk has passed.
Women may often come to learn that it may be more convenient to postpone sexual intercourse until the early morning and then to drink the fluids through the course of the day