How long sperm can survive after leaving the male body depends on the surrounding environment. It survives for a longer period of time in a 37°C environment, and also if it is in the female vagina, it will have a certain spermicidal effect due to the lactic acid secreted by more lactobacillus bacteria in the vagina, so the survival time of active sperm inside the vagina is shorter, that is, half a day. Once the sperm move from the vagina to the cervix, the survival time inside the cervix will be greatly extended, and after passing through the cervix into the uterus and fallopian tubes, the survival time of active sperm can reach about 2-3 days. If the temperature is lowered further, the sperm can remain viable for several weeks, and even longer with liquid nitrogen freezing, which can be used for long-term storage. Once in the fallopian tube, the sperm die in about 24-36 hours. Therefore, it is recommended that couples who are trying to conceive have intercourse every other day during the peri-ovulatory period, i.e., the three days before and after ovulation, to ensure that as many good quality sperms as possible can be used for fertilization, and that a large number of sperms can survive in the female reproductive tract.