Your menstrual cycle helps your body prepare for pregnancy every month. It also makes you have a period if you’re not pregnant. Your menstrual cycle and period are controlled by hormones like estrogen and progesterone.​

You have 2 ovaries, and each one holds a bunch of eggs. During your menstrual cycle, hormones make the eggs in your ovaries mature – when an egg is mature, that means it’s ready to be fertilised by a sperm cell. These hormones also make the lining of your uterus thick and spongy. This lining is made of tissue and blood with lots of nutrients to help a pregnancy grow.​

About halfway through your menstrual cycle, your hormones tell one of your ovaries to release a mature egg – this is called ovulation. Most people don’t feel it when they ovulate, but some ovulation symptoms are bloating, spotting, or a little pain in your lower belly that you may only feel on one side.​

Once the egg leaves your ovary, it travels through one of your Fallopian tubes toward your uterus.​

If pregnancy doesn’t happen, your body doesn’t need the thick lining in your uterus. Your lining breaks down, and the blood, nutrients, and tissue flow out of your body through your vagina – this is your period.​

If you do get pregnant, your body needs the lining – that’s why your period stops during pregnancy. Your period comes back when you’re not pregnant anymore.​

When can I get pregnant during my menstrual cycle?​

You have the highest chance of getting pregnant on the days leading up to ovulation (when your ovary releases a mature egg) – these are called fertile days.​

Your egg lives for about 1 day after it’s released from your ovary, and sperm can live in your uterus and Fallopian tubes for about 6 days after sex. So you can usually get pregnant for around 6 days of every menstrual cycle: the 5 days before you ovulate, and the day you ovulate. You can also get pregnant a day or so after ovulation, but it’s less likely.​

Ovulation usually happens about 14 days before your period starts – but everyone’s body is different. You may ovulate earlier or later, depending on the length of your menstrual cycle. Many people track their menstrual cycles and other fertility signs to help them figure out when they’re ovulating.​

Some people have very regular cycles, and other people’s cycles vary from month to month. It’s really common for young people to have irregular periods. Since your period can be unpredictable, it’s hard to know for sure when you’ll ovulate (even if you’re carefully tracking your menstrual cycle).