Getting pregnant (conception)

 

To become pregnant (conceive) an egg must be fertilised by a sperm and become implanted in the uterus. Conception is a process that begins with fertilisation and ends with successful implantation of a fertilised egg in the uterus.

 

Finding your most fertile time.

The menstrual cycle is the process during which an egg develops and is released from an ovary, and the lining of the uterus thickens in preparation for a possible pregnancy. If a woman does not become pregnant, the lining of the uterus is shed as her period. These events are caused by hormones – chemical messengers which travel around the body in the blood stream.

 

 

How long does the cycle take?

The number of days in the menstrual cycle is calculated from the first day of a period to the day before the start of the next period.

The average length of the menstrual cycle is around 28 days, although many women have longer or shorter cycles and this is normal.

 

 

What happens during the menstrual cycle?

The first day of the period is known as day one of the cycle. When a woman has her period about 20 eggs start to develop in the ovary.

The hormone estrogen causes the lining of the uterus (endometrium) to start to thicken in preparation for a fertilised egg. It also causes the cervical mucus (noticed as vaginal secretions) to become clearer, wetter and more stretchy, allowing sperm to reach an egg more easily.

Regardless of how long or short a woman’s cycle is, ovulation (egg release from an ovary) will usually happen around 10–16 days before the start of her next period. However, the time from the first day of the period to ovulation can vary between women.

Occasionally, more than one egg is released (if this happens it will occur within 24 hours of the first egg being released). If more than one egg is fertilised it can lead to a multiple pregnancy, such as twins.

Ovulation triggers the production of a second hormone, progesterone. This prepares the lining of the uterus even further, ensuring that it is spongy, thick and full of nutrients so that a fertilised egg can implant into it.

After ovulation the cervical mucus goes back to being thick and sticky. If the egg is not fertilised it will be reabsorbed naturally by the body, the level of hormones falls, and this menstrual cycle comes to an end.

The cycle then begins again. The lining of the uterus breaks down and leaves the body through the vagina as a period, also called menstruation.

 

Ovulation.

An egg is released from one of your ovaries during each menstrual cycle. This is called ovulation. You can get pregnant only for a few days around the time of ovulation. This is known as the fertile time. The egg travels down one of your fallopian tubes towards your uterus. The egg lives for up to 24 hours only. Each month, the lining of your uterus thickens to prepare for a possible pregnancy.

 

Fertilisation and implantation.

During sex, when your partner ejaculates (comes), millions of sperm enter the vagina. Many of these will swim up through your cervix (the entrance to your uterus) into the uterus and the fallopian tubes. Although millions of sperm may be released, only one sperm will enter the egg. This is known as fertilisation. The fertilised egg travels down the fallopian tube over a number of days and eventually reaches the uterus, where it attaches itself to the thick nutritious lining.

Implantation has now taken place and conception is complete. The time from ovulation to implantation is around ten days.

 

 

Confirming you are pregnant.

The earliest and most reliable sign of pregnancy for women with a regular menstrual cycle is a missed period. Sometimes women who are pregnant have a shorter or lighter period than normal.

You can carry out a pregnancy test from the first day of a missed period. Tests carried out earlier than this are not always accurate. If you don’t have regular periods, the earliest time you can do a test is 21 days from the last time you had unprotected sex. For some women the test does not show positive until their period is at least a week late.

Pregnancy tests look for the pregnancy hormone human chorionic gonadotrophin (hCG), which is found in the urine of pregnant women. A positive test is almost always correct. But women can sometimes get a negative result if the test is carried out too early or not correctly, even though they may be pregnant.

 

Why it might take longer to get pregnant.

Even if you keep track of your body’s changes and have sex 2–3 times a week, it may still take a while to get pregnant. There are a number of factors that can affect getting pregnant. You should not be too surprised or upset if you do not get pregnant straightaway. Very often it can take much longer, and this is normal.

Ovulation.

One possible problem is that ovulation may not occur every month. If you have recently stopped taking hormonal contraception, ovulation may be delayed or irregular for a short time. If you have been using a contraceptive injection, ovulation may be delayed or irregular for up to a year. If you are worried you might not be ovulating, see your doctor.

Implantation.

Even if there are sperm waiting for the egg when you ovulate, you may not become pregnant in the first few months of trying. Sometimes fertilisation does take place but the egg does not implant securely and is lost in the next period.

Age.

Your chances of becoming pregnant decrease as you get older as the quantity and quality of eggs deteriorate with age. It can take longer and be more difficult to get pregnant if you are over 35. However, many women over 35 have healthy pregnancies and babies.

Sperm.

There may be a problem with the number or quality of your partner’s sperm. Sperm production can be damaged by mumps, untreated sexually transmitted infections, injury to the testicles, excessive heat (such as hot baths), tight fitting underwear, alcohol, smoking or recreational drugs, or there may be unknown causes.