How often does menstruation occur in human females on average?

Step-by-step solution

The reproductive cycle in the female primates (e.g. monkeys, apes and human beings) is called menstrual cycle. The first menstruation begins at puberty and is called menarche. In human females, menstruation is repeated at an average interval of about 28/29 days , and the cycle of events starting from one menstruation till the next one is called the menstrual cycle.