What is the most fertile day in a m enstrual cycle ?

Dear Doctor,
What is the most fertile day for a girl whose menstrual cycle is 24 days and what brings about variations in the number of menstruation days?
Anonymous

Dear Anonymous,
The most fertile days, usually, include the day of ovulation, the days preceding and following ovulation.
Ovulation is a part of the female menstrual cycle, where a mature ovarian follicle (part of the ovary) discharges an egg for fertilisation.

The egg released during ovulation has a lifespan of up to 24 hours, but the sperm survives in the vaginal environment for an average of seven days. Hence, the fertile days fall into the ovulation phase.

For instance, if your period starts on the first day of the month, your fertile day is highly likely to be on the 11th and 12th day after your periods. On average, seven days from the day you stop menstruating are your safe days.

To calculate the actual date of ovulation, one must figure out how long their cycle is. Majority of women have cycles that are, on average, 28 days long.

There are also signs that will indicate you are ovulating. Change in body temperature is one of them. The body normally increases by 0.50C to 10C, when a woman is ovulating. One also experiences a strong urge for sex, the cervix opens to allow in the sperm for fertilisation and more whitish vaginal fluids are produced.

There are several factors that bring about variations. Stress and ill-health before menstruation are likely to affect the cycle. Also, birth control pills interfere with the normal body physiology because they tamper with the hormones.