Your menstrual cycle

The menstrual cycle is the process in which an egg develops in your ovaries and is released, and the lining of the womb is prepared for a possible pregnancy. The lining of the womb is then shed as a period if a woman doesn’t get pregnant. These events are caused by hormones – chemical messages which travel around the body in the blood stream.

The menstrual cycle is the time from the first day of a period until the day before the next period starts. The length of the menstrual cycle varies – it can be as short as 21 days or as long as 40 days. On average, it will be about 28 days.

During the cycle, about 20 eggs start to ripen in the ovary, although only one of these will finally be released at ovulation. Then the hormone oestrogen causes a new womb lining to start to thicken in preparation for a fertilised egg. It also causes the mucus in the cervix to become thinner and more stretchy, allowing sperm to pass through the cervix more easily and swim to the egg.

Ovulation is when an egg is released from an ovary. In all cycles, regardless of how long or short they are, ovulation will always happen around 12-16 days before the start of the next period. It is the time from the first day of the period to ovulation that can change. Ovulation occurs in most, but not all cycles. Occasionally, more than one egg is released which, if fertilised, can lead to a multiple pregnancy such as twins. Once the egg has been released, it travels down the fallopian tube to the womb.

A female is most likely to get pregnant around ovulation, as this is the most fertile time. However, ovulation can vary each month so it makes it hard to know exactly when it occurs. Sperm can also live in the female body for around five days after sex, so pregnancy is possible at virtually any time in the menstrual cycle. Men produce around 300 million sperm when they ejaculate and just one sperm is enough.

Ovulation triggers the production of a second hormone, progesterone. This prepares the womb lining even more, ensuring that it’s spongy and thick and full of nutrients so that a fertilised egg can settle or implant into it. After ovulation the mucus in the cervix goes back to being thick and sticky. If the egg is not fertilised, it will be reabsorbed naturally, the level of hormones drops, and this menstrual cycle comes to an end. The cycle then begins again with the womb lining breaking down and being shed through the vagina as a period.

Period facts

• periods usually start when a girl is aged 12 or 13, but can be as young as eight or as old as 18
• the average amount of menstrual blood lost in a whole period is three to five tablespoons
• a period usually lasts between three and seven days.
• period blood is often thick and reddish brown and may have small lumps in it, especially at the start of the period
• period blood can smell when it comes into contact with the air, so it’s important to change the towel or tampon regularly

When girls first have periods, the time between one period and the next may vary so it can be difficult to know exactly when the next one will be. It is normal that it may take a while for the menstrual cycle to become regular. Recording periods on a calendar or in a diary can help work out when the next period is due.

Living with your period

Changes in hormone levels can affect moods. A few days before a period is due, a woman may feel moody and tearful, her breasts may become tender or get larger and she may get spots on her face. Periods are often accompanied with pain, due to contractions of the womb muscle, which some women experience more than others. This can be really frustrating and upsetting, but holding a hot water bottle against the stomach and taking painkillers may help. Taking the combined contraceptive pill can help painful periods, but there are other alternatives – seek advice from a doctor or nurse.

Young women often get anxious about putting a tampon in for the first time in case it hurts, but it shouldn’t if they are relaxed. Read the instructions to make sure you put them in correctly. If the tampon feels uncomfortable, it may not be in far enough.

Some women find using some extra lubricant (like K-Y jelly) can help. You can use towels or tampons during a period (or sometimes women alternate between them). One method isn’t better than the other, it’s up to you to decide which you feel more comfortable using.

It may take some time to get used to having periods and feeling confident living with them. But periods are a normal, healthy part of being female and they shouldn’t stop her from doing things she enjoys – such as playing sport or swimming. It’s your decision what you do or don’t do when you have a period.

Toxic Shock Syndrome

Toxic Shock Syndrome (TSS) is a rare condition associated with using tampons which results in a type of blood poisoning. Two or more of the following symptoms can be signs of it - vomiting, getting a rash, a sore throat, a sudden fever and diarrhoea. If you get any of these and are concerned about TSS, you should stop using tampons and seek medical advice immediately.

Please feel free to contact us at swish@brighton-hove.gov.uk with your questions or comments.