Though it may take some time for your normal menstrual cycle length to become predictable, a menstrual cycle is made up of four distinct phases, regardless of how long or short yours is.
First is menstruation. The first day of your period is actually Day 1 of your period, making menstruation – a.k.a getting your period – the first phase of your menstrual cycle. This is when the lining of your uterus is shed, and comes out of your vagina as menstrual fluid, a mix of blood and tissue.
Next is what’s called the follicular phase, or pre-ovulation. This is when one of your ovaries develops follicles, liquid filled sacs containing an egg. One of these eggs will be released during ovulation – the next stage of your menstrual cycle. Your ovaries take turns developing follicles. So, one month your left ovary develops follicles, while the next month your right ovary gets its turn, then your left in the month following, and so on. The lining of your uterus also thickens during this phase.
Ovulation is when your ovary releases a mature egg. The egg then travels down your fallopian tubes and into your uterus. At this point, if your egg is fertilised by a male sperm, a baby will grow inside you. How many days into your menstrual cycle ovulation occurs depends on your menstrual cycle duration. It happens 14 days before the start of your next period. For example, if you have a 28-day cycle, this means ovulation will occur 14 days after the first day of your period. But if your menstrual cycle is just 22 days, you will ovulate only 8 days after the first day of your period.
The last phase of your menstrual cycle is called the luteal phase, or pre-menstruation. If your egg wasn’t fertilised, the lining of your uterus, also known as your endometrium in medical speak, will start to break down. This is what can make some girls feel achy and crampy leading up to their period.