When you hear the term ‘menstrual cycle’, you might think only of your period, but did you know that your period is only one small part of the cycle?
Toni Belfield, a fertility awareness teacher and sexual health expert, explains it simply. “The menstrual cycle is the time from the first day of a woman’s period to the day before her next period.”
Every woman’s menstrual cycle varies in length, but the population average is around every 28 days. That said, some people have regular cycles that range between 21 to 40 days – this is completely normal
“Girls can start their periods anywhere from age 10 upwards, but the average is around 12 years. The average age for the menopause (when periods stop) in this country (the UK) is 50 to 55.”
That means that between the ages of 12 and 52, most women and AFAB (assigned female at birth) people will have approximately 480 periods. This number will be lower if she has pregnancies, breastfeeds (which can prevent menstruation), or any medical conditions that cause dysmenorrhea (when periods stop in a woman who has not undergone the menopause).
What happens during a menstrual cycle?
Before we detail what happens during a menstrual cycle, it’s essential to understand the female reproductive system.
A typical female reproductive system includes:
Two ovaries – the organs that develop, store, and release eggs
A uterus (womb) – where a fertilised egg implants and a foetus develops into a baby
Fallopian tubes – thin tubes that connect the uterus and the ovaries
Cervix – The passage between the vagina and the uterus
Vagina – The muscular canal that connects the vulva (external genitals) to the cervix
Every month, hormones such as oestrogen and progesterone control the menstrual cycle. Oestrogen causes the ovaries to release an egg, which is called ovulation. After this occurs, progesterone prepares the womb for embryo implantation by thickening the uterine lining.
If a pregnancy doesn’t occur, the woman’s body reabsorbs the egg and hormone levels fall. This causes that thickened uterine lining to fall away and leave the body vaginally, which is what we call menstruation, or ‘getting a period.”
The egg travels down the fallopian tubes. If pregnancy doesn’t occur, the egg is reabsorbed into the body. Levels of oestrogen and progesterone fall, and the womb lining comes away and leaves the body as a period (the menstrual flow).
If you have any physical irregularities, they can lead to hormonal imbalances that can cause you to have trouble getting pregnant. Speak to your doctor if you have been trying for more than one year if you are under 35, and for more than six months if you are over 35.
What are periods?
From the description above, you can see that a period is comprised of blood and uterine lining that is not needed.
Day 1 of your menstrual cycle is the first day of your period, and then you can start counting once again. Many fertility treatments and medical interventions require you to know ‘Day 1’ of your period, so it’s smart to jot this date down or track it with an app.
While it can feel like you’re losing a lot of blood, most women actually bleed less than they estimate. According to Belfield, “periods last around 2 to 7 days, and women lose about 3 to 5 tablespoons of blood in a period.”
That said, some women and AFAB people bleed even more than this, especially due to certain medical conditions (like endometriosis) or when they are approaching the menopause. If you have an extremely heavy period, speak to your GP and ask for a referral to a gynaecologist.
What is ovulation?
Ovulation occurs when a woman releases an egg from her ovaries, which usually happens once per cycle. After she ovulates, the egg lives and is available for fertilisation for approximately 24 hours.
If a man’s sperm meets this egg and fertilises it, a pregnancy will occur. While we often refer to the ‘fertile window’ as being between 12 – 36 hours, sperm can live in the fallopian tubes for up to seven days! That means that your ‘fertile window’ can actually be as long as eight days.
In some cases, a woman’s ovaries release more than one egg, which is how fraternal twins can occur.
Did you know that female babies are born with all of their eggs? However, the ovaries prepare each egg in the few months before it is released, so lifestyle factors and diet are crucial when trying to conceive. Remember – if you don’t ovulate, you can’t get pregnant, so it is important to track your ovulation.
When are women most fertile?
Women and AFAB people can only get pregnant when they are ovulating, and this happens around 10 to 16 days before they next menstruate. But don’t rely on this generic metric too much, as some women have cycles of different lengths.
Back to Belfield – she says, “it’s not accurate to say that all women are fertile on day 14 of the menstrual cycle. This might be true for women who have a regular, 28-day cycle, but it won’t apply to women whose cycles are shorter or longer.”
If you want to track your ovulation, you can do so with a basal body temperature thermometer, which tracks the slight temperature increase that occurs just before a woman ovulates. You can also use urine test strips or assess your cervical mucous. It will become thicker and more viscous before you ovulate, with an ‘egg white’ texture.
If you’re trying to get pregnant, it’s a good idea to have intercourse daily or every other day throughout your fertile window (which can be up to eight days long).
By arming yourself with this vital information, you can take control of your fertility. If you are experiencing irregular menstrual cycles or failing to track ovulation, it’s time to speak with your GP or a fertility specialist.
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