Getting pregnant (conception) happens when a man's sperm fertilises a woman's egg. For some women, this happens quickly, but for others it can take longer. Out of every 100 couples trying for a baby, 80 to 90 will get pregnant within one year. The rest will take longer, or may need help to conceive.
To understand conception and pregnancy, it helps to know about the male and female sexual organs, and to understand how a woman's monthly menstrual cycle and periods work.
The menstrual cycle is counted from the first day of a woman's period (day one). Some time after her period she will ovulate, and then around 12-14 days after this she'll have her next period. The average cycle takes 28 days, but shorter or longer cycles are normal.
Planning for success
A healthy diet is an important part of a healthy lifestyle at any time, but is especially vital if you're pregnant or planning a pregnancy. Eating healthily during pregnancy will help your baby to develop and grow.
You don't need to go on a special diet, but it's important to eat a variety of different foods every day to get the right balance of nutrients that you and your baby need.
It's best to get vitamins and minerals from the foods you eat, but when you're pregnant you need to take a folic acid supplement as well, to make sure you get everything you need.
You will probably find that you are hungrier than usual, but you don't need to "eat for two" – even if you are expecting twins or triplets.
Try to have a healthy breakfast every day, because this can help you to avoid snacking on foods that are high in fat and sugar.
Take Folic Acid
Take a 400 microgram (400mcg) supplement of folic acid every day while you're trying to get pregnant, and up until you're 12 weeks pregnant.
Folic acid reduces the risk of your baby having a neural tube defect, such as spina bifida.
Smoking during pregnancy has been linked to a variety of health problems, including:
- premature birth
- low birth weight
- sudden infant death syndrome (SIDS) – also known as cot death
- breathing problems or wheezing in the first six months of life
Don’t drink alcohol
Don't drink alcohol if you're pregnant or trying to get pregnant. Alcohol can be passed to your unborn baby. The Chief Medical Officers recommend that the safest approach is not to drink alcohol at all.
Foods to avoid
Don't eat mould-ripened soft cheese (cheeses with a white rind) such as brie and camembert. This includes mould-ripened soft goats' cheese, such as chèvre. Also avoid soft blue-veined cheeses such as Danish blue, gorgonzola and Roquefort. These cheeses are only safe to eat in pregnancy if they've been cooked.
Avoid all types of pâté, including vegetable pâtés, as they can contain listeria.
Do not eat raw or undercooked meat, including meat joints and steaks cooked rare, because of the potential risk of toxoplasmosis. Many cold meats, such as salami, prosciutto, chorizo and pepperoni, are not cooked, they're just cured and fermented. This means there's a risk they contain toxoplasmosis-causing parasites.
Don't eat liver or products containing liver, such as liver pâté, liver sausage or haggis, as they may contain a lot of vitamin A. Too much vitamin A can harm your baby.
Always eat cooked, rather than raw, shellfish – including mussels, lobster, crab, prawns, scallops and clams – when you're pregnant, as they can contain harmful bacteria and viruses that can cause food poisoning. Cold pre-cooked prawns are fine.
It's fine to eat raw or lightly cooked fish in dishes like sushi when you're pregnant, as long as any raw wild fish used to make it has been frozen first.
Avoid raw or partially cooked eggs if you're pregnant.
You can eat peanuts or food containing peanuts, such as peanut butter, during pregnancy, unless you're allergic to them or a health professional advises you not to.
Soft ice creams should be fine to eat when you're pregnant, as they are processed products made with pasteurised milk and eggs, so any risk of salmonella food poisoning has been eliminated.
Wash fruit, vegetables and salads to remove all traces of soil and visible dirt.
High levels of caffeine can result in babies having a low birthweight, which can increase the risk of health problems in later life. Too much caffeine can also cause miscarriage.
There's little information on the safety of herbal and green teas in pregnancy, so it's best to drink them in moderation. The FSA recommends drinking no more than around four cups of herbal or green tea a day during pregnancy, and to seek advice from your GP or midwife if you're unsure about which herbal products are safe to consume.
You can have moderate amounts of liquorice sweets or liquorice teas in pregnancy – there's no recommendation to avoid them. However, you should avoid the herbal remedy liquorice root.
Keep to a healthy weight
If you're overweight, you may have problems getting pregnant, and fertility treatment is less likely to work. Being overweight (having a BMI over 25) or obese (having a BMI over 30) also raises the risk of some pregnancy problems, such as high blood pressure, blood clots, miscarriage and gestational diabetes.
Before you get pregnant you can use the BMI healthy weight calculator to work out your BMI. However, this may not be accurate once you're pregnant, so consult your midwife or doctor.
Vitamins and supplements
Eating a healthy, varied diet in pregnancy will help you to get most of the vitamins and minerals you need. But when you are pregnant you will need to take a folic acid supplement. It's recommended that you take 400 micrograms (mcg) of folic acid each day – you should take this from before you are pregnant until you are 12 weeks pregnant.
The Department of Health also advises you to consider taking a vitamin D supplement.
Do not take vitamin A supplements, or any supplements containing vitamin A (retinol), as too much could harm your baby. Always check the label.
The more active and fit you are during pregnancy, the easier it will be for you to adapt to your changing shape and weight gain. It will also help you to cope with labour and get back into shape after the birth.
Keep up your normal daily physical activity or exercise (sport, running, yoga, dancing, or even walking to the shops and back) for as long as you feel comfortable.
The best time to get pregnant
You're most likely to get pregnant if you have sex within a day or so of ovulation (releasing an egg from the ovary). This is usually about 14 days after the first day of your last period, if your cycle is around 28 days long.
An egg lives for about 12-24 hours after being released. For pregnancy to happen, the egg must be fertilised by a sperm within this time.
Sperm can live for up to seven days inside a woman's body. So if you've had sex in the days before ovulation, the sperm will have had time to travel up the fallopian tubes to "wait" for the egg to be released.
It's difficult to know exactly when ovulation happens, unless you are practising natural family planning, or fertility awareness.
Have frequent sex
If you want to get pregnant, having sex every couple of days throughout the month will give you the best chance.
You don't need to time having sex only around ovulation. Trying to do this can be stressful, and being stressed may mean you have less sex.
The male sexual organs
The penis is made of erectile tissue. This tissue acts like a sponge and, when it becomes filled with blood, the penis becomes hard and erect. Men have two testes (testicles), which are glands where sperm are made and stored. The testes are contained in a bag of skin that hangs outside the body, called the scrotum.
The scrotum helps to keep the testes at a constant temperature, just below the temperature of the rest of the body. This is necessary for the sperm to be produced. When it's warm, the scrotum hangs down, away from the body, to help keep the testes cool. When it's cold, the scrotum draws up, closer to the body for warmth.
Two tubes, called the vas deferens, carry sperm from the testes to the prostate and other glands. These glands add secretions that are ejaculated along with the sperm. The urethra is a tube that runs down the length of the penis from the bladder, through the prostate gland to an opening at the tip of the penis. Sperm travel down this tube to be ejaculated.
The female sexual organs
A woman's reproductive system is made up of both external and internal organs. These are found in what is usually referred to as the pelvic area, the part of the body below the belly button.
The external organs are known as the vulva. This includes the opening of the vagina, the inner and outer lips (labia) and the clitoris.
The woman's internal organs are made up of:
The pelvis: this is the bony structure around the hip area, which the baby will pass through when he or she is born.
Womb or uterus: the womb is about the size and shape of a small, upside-down pear. It is made of muscle and grows in size as the baby grows within it.
Fallopian tubes: these lead from the ovaries to the womb. Eggs are released from the ovaries into the fallopian tubes each month, and this is where fertilisation takes place.
Ovaries: there are two ovaries, each about the size of an almond; they produce the eggs, or ova.
Cervix: this is the neck of the womb. It is normally almost closed, with just a small opening through which blood passes during the monthly period. During labour, the cervix dilates (opens) to let the baby move from the uterus into the vagina.
Vagina: the vagina is a tube about three inches (8cm) long, which leads from the cervix down to the vulva, where it opens between the legs. The vagina is very elastic, so it can easily stretch around a man's penis, or around a baby during labour.
The woman's monthly cycle
The video below shows what happens during the menstrual cycle. Ovulation occurs each month when an egg is released from one of the ovaries. Occasionally, more than one egg is released, usually within 24 hours of the first egg.
At the same time, the lining of the womb begins to thicken and the mucus in the cervix becomes thinner, so that sperm can swim through it more easily.
The egg begins to travel slowly down the fallopian tube. If a man and a woman have recently had sex, the egg may be fertilised here by the man's sperm.
The lining of the womb is now thick enough for the egg to be implanted in it after it has been fertilised.
If the egg is not fertilised, it passes out of the body during the woman's monthly period, along with the lining of the womb, which is also shed.
The egg is so small that it cannot be seen.