Periods and fertility in the menstrual cycle – Periods

Vaginal secretions (sometimes called vaginal discharge) change during the menstrual cycle. Around the time of ovulation, they become thinner and stretchy, a bit like raw egg white.

Pregnancy – identifying fertile days

Fertile days are the days a woman is most likely to get pregnant.

Infertility is a related topic.

Information

When trying to become pregnant, many couples plan intercourse between days 11 to 14 of the woman’s 28-day cycle. This is when ovulation occurs.

It is hard to know exactly when ovulation will happen. Health care providers recommend that couples who are trying to have a baby have sex between days 7 and 20 of a woman’s menstrual cycle. Day 1 is the first day of menstrual bleeding. In order to become pregnant, having sex every other day or every third day works just as well as having sex every day.

• Sperm can live inside a woman’s body for less than 5 days.
• A released egg lives for less than 24 hours.
• The highest pregnancy rates have been reported when the egg and sperm join together within 4 to 6 hours of ovulation.

Watch this video about:Ovulation

If you have an irregular menstrual cycle, an ovulation predictor kit can help you know when you are ovulating. These kits check for luteinizing hormone (LH) in the urine. You can buy them without a prescription at most drug stores.

There are various other methods to help detect when you are most likely to be able to conceive a baby.

Note: Some lubricants can interfere with conception. If you are trying to get pregnant, you should avoid all douches and lubricants (including saliva), except those specifically designed to not interfere with fertility (such as Pre-seed). Lubricants should never be used as a method of birth control.

EVALUATING YOUR CERVICAL FLUID

Cervical fluid protects the sperm and helps it move toward the uterus and fallopian tubes. Cervical fluid changes occur when the woman’s body is getting ready to release an egg. There are clear differences in how it looks and feels during the woman’s monthly menstrual cycle.

• No cervical fluid is present during the menstrual period.
• After the period is over, the vagina is dry and no cervical fluid is present.
• Fluid then turns to a sticky/rubbery fluid.
• The fluid becomes very wet/creamy/white which indicates FERTILE.
• The fluid becomes slippery, stretchy, and clear like an egg white, which means VERY FERTILE.
• After ovulation, the vagina becomes dry again (no cervical fluid). The cervical mucus may become more like thick bubble gum.

You can use your fingers to see how your cervical fluid feels.

• Find the fluid inside the lower end of the vagina.
• Tap your thumb and first finger together — if the fluid stretches while you spread your thumb and finger apart, this could mean ovulation is near.

TAKING YOUR BASAL BODY TEMPERATURE

After you ovulate, your body temperature will rise and stay at a higher level for the rest of your ovulation cycle. At the end of your cycle, it falls again. The difference between the 2 phases is most often less than 1 degree.

• You can use a special thermometer to take your temperature in the morning before you get out of bed.
• Use a glass basal thermometer or a digital thermometer that is accurate to the tenth of a degree.
• Keep the thermometer in your mouth for 5 minutes or until it signals you that it is done. Try not to move too much, as activity can raise your body temperature slightly.

If your temperature is between 2 marks, record the lower number. Try to take your temperature at the same time every day, if possible.

Create a chart and write down your temperature every day. If you look at a complete cycle, you will probably notice a point at which the temperatures become higher than in the first part of your cycle. The rise is about 0.2 degrees or more above the previous 6 days.

Temperature is a useful indicator of fertility. After checking for several cycles, you may be able to see a pattern and identify your most fertile days.

Periods and fertility in the menstrual cycle – Periods

The length of the menstrual cycle varies from woman to woman, but the average is to have periods around every 28 days. Regular cycles that are longer or shorter than this, from 21 to 35 days, are normal.

The menstrual cycle is the time from the first day of a woman’s period to the day before her next period.

Girls can start their periods anywhere from age 8 upwards, but the average is around 12 years. The average age for the menopause (when periods stop) in this country is 51.

Between the ages of 12 and 52, a woman will have around 480 periods, or fewer if she has any pregnancies.

What happens during the menstrual cycle?

To understand the menstrual cycle, it helps to know about the reproductive organs inside a woman’s body. These are:

• 2 ovaries – where eggs are stored, developed and released
• the womb (uterus) – where a fertilised egg implants and a baby develops
• the fallopian tubes – two thin tubes that connect the ovaries to the womb
• the cervix – the entrance to the womb from the vagina
• the vagina

The menstrual cycle is controlled by hormones. In each cycle, rising levels of the hormone oestrogen cause the ovary to develop and release an egg (ovulation). The womb lining also starts to thicken.

In the second half of the cycle, the hormone progesterone helps the womb to prepare for implantation of a developing embryo.

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).

The time from the release of an egg to the start of a period is around 10 to 16 days.

Watch an animation about how the menstrual cycle works.

Video: menstrual cycle

This animation explains in detail how the menstrual cycle works.

Media last reviewed: 21 October 2023
Media review due: 21 October 2026

What are periods?

A period is made up of blood and the womb lining. The first day of a woman’s period is day 1 of the menstrual cycle.

Periods last around 2 to 7 days, and women lose about 20 to 90ml (about 1 to 5 tablespoons) of blood in a period.

Some women bleed more heavily than this, but help is available if heavy periods are a problem.

What happens during ovulation?

Ovulation is the release of an egg from the ovaries. A woman is born with all her eggs.

Once she starts her periods, 1 egg develops and is released during each menstrual cycle.

Pregnancy happens if a man’s sperm meet and fertilise the egg. Sperm can survive in the fallopian tubes for up to 7 days after sex.

Occasionally, more than 1 egg is released during ovulation. If more than 1 egg is fertilised it can lead to a multiple pregnancy, such as twins.

A woman can’t get pregnant if ovulation doesn’t occur. Some methods of hormonal contraception – such as the combined pill, the contraceptive patch and the contraceptive injection – work by stopping ovulation.

When are you most fertile?

Theoretically, there’s only a short time when women can get pregnant, and that is the time around ovulation.

It’s difficult to pinpoint exactly when ovulation happens, but in most women it happens around 10 to 16 days before the next period.

Women who have a regular, 28-day cycle are likely to be fertile around day 14 of their menstrual cycle, but this won’t apply to women whose cycles are shorter or longer.

It’s possible (although not very likely) to get pregnant soon after your period finishes if you ovulate early or have a short menstrual cycle.

Having sex without penetration

It’s also possible to get pregnant if you have sex without penetration (the penis entering your vagina).

Pregnancy can happen if sperm comes into contact with your vagina if, for example:

• you partner ejaculates very close to your vagina
• your partner’s erect penis comes into contact with your vagina or vulva (genital area)

The risk of getting pregnant in this way is very low, but it can happen.

Normal vaginal secretions

Vaginal secretions (sometimes called vaginal discharge) change during the menstrual cycle. Around the time of ovulation, they become thinner and stretchy, a bit like raw egg white.

See your GP if you are concerned about a change in your vaginal discharge.

More information

Page last reviewed: 05 January 2023
Next review due: 05 January 2026

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