Stages of pregnancy

You may get constipated when you’re pregnant because pregnancy hormones relax and slow the muscles of your digestive system and bowels. Photo/FILE

Conception

An egg is released from one of your ovaries around 14 days before your period begins. This is called ovulation. This usually happens in the middle of a 28-day cycle, but this can vary between women, and your cycle may be longer or shorter than this.

After sexual intercourse, the egg can be met by sperm in the fallopian tube and one of these may be able to fertilise it. Once fertilised, the egg continues to travel along the fallopian tube towards your womb (uterus) where it will bury itself in the lining in a process called implantation.

The process that starts with fertilisation and ends at implantation is called conception. This takes around seven days. The fertilised egg is growing all the time and is now called an embryo.

When you become pregnant, your womb stops shedding its lining as it usually would at every period. You won’t have any periods while you’re pregnant. Missing a period is one of the early signs of pregnancy.

You can buy pregnancy tests at pharmacies (chemists or drugstores) and supermarkets. Most types of pregnancy test can detect that you’re pregnant from just after your first missed period.

There are some types that are able to give a result sooner than this. If the result of the pregnancy test is positive, it indicates that you’re pregnant. Your doctor may also be able to arrange a test for you.

Pregnancy typically lasts 37 to 42 weeks, with the average being 40 weeks. This is calculated from the first day of your last period and often broken down into thirds, called trimesters.

First trimester (one to 12 weeks)

You

Your body goes through a lot of hormonal changes in early pregnancy. This can have a number of physical effects on you.

As well as missing your first period, you may notice that your breasts feel tender. Your nipples and the area around them (the areola) may become larger and darker. You may find you need to pass urine more often because your growing womb starts to press on your bladder. Feeling very tired during the first trimester is common.

Another frequent symptom of the first trimester is feeling sick and perhaps also vomiting. This is known as ‘morning sickness’, but it can happen at any time of the day.

Although the cause of morning sickness hasn’t been established, it’s likely to be because of the high levels of hormones that are needed to keep your pregnancy progressing.

You can help yourself by taking time to get up slowly in the morning, eating little and often, getting plenty of rest and drinking enough fluids. It may help you to stay away from smells and tastes that you find make you feel sick.

Having morning sickness may make you feel very unwell, but it’s important to remember that your unborn baby is unlikely to be affected by it.

However, if at any time you find you can’t keep any food or fluid down, seek advice from your doctor or midwife as soon as you can. If vomiting means you become very dehydrated, this can lead to complications.

You may get constipated when you’re pregnant because pregnancy hormones relax and slow the muscles of your digestive system and bowels.

You can help to prevent constipation by eating plenty of fibre-rich foods, such as green, leafy vegetables and fruit, and making sure you drink enough fluids every day. The relaxation of the muscles in your digestive system can also increase heartburn. Spicy and fatty foods can make heartburn worse, so you may prefer not to eat these.

If you hadn’t already started taking folic acid before you became pregnant, you should take 400 micrograms (µg) a day until at least week 12 of pregnancy. Folic acid is important for the development of your baby’s brain and spinal cord.

Too little folic acid in early pregnancy may lead to a higher risk of your baby having a problem with his or her spinal cord (a neural tube defect), such as spina bifida. Some women who have other health conditions before they become pregnant may be advised to take a higher daily dose of folic acid, up to 5000µg daily. Talk to you doctor or midwife to find out which dose you need to take.

If you smoke, quitting will protect your baby from a number of health problems that can occur during your pregnancy, or after your baby is born and in childhood.

It’s best that you don’t drink any alcohol during pregnancy because alcohol has been linked to a number of developmental problems in babies. If you choose to drink alcohol when you’re pregnant, limit how much you drink to one to two units of alcohol, once or twice a week.

Your baby

Over the first 12 weeks of pregnancy, your baby will begin as a microscopic ball of cells and develop quickly into an embryo. By week 10, eight weeks after fertilisation, all your baby’s organs are present, even if they are not yet fully formed.

Your baby is now known as a foetus. The placenta is fully formed and working to transfer nutrients from your blood, through the umbilical cord and into your baby. In return, all the waste products from your baby are transferred back into your circulation, so that you can get rid of them.

By week 12, your baby is about 60mm long, his or her eyes are formed, but tightly shut and the ears are still forming. The brain is growing most rapidly, which means that your baby’s head is much larger than his or her body.

Second trimester (13 to 27 weeks)

You
Your pregnancy will start to show during the second trimester – when this happens varies from woman to woman.

If you had any vomiting or feeling sick in your first trimester, this usually gets better by the time you are 16 to 20 weeks pregnant. You may get backache, hip or pelvic pain because pregnancy hormones cause your ligaments and tendons to relax and your posture may change as your baby grows.

You may first feel the baby move around 18 to 20 weeks of pregnancy, but this varies between women and may be a few weeks earlier if it's not your first pregnancy. The movements become much more vigorous and obvious as the baby gets bigger and stronger.

Your baby

In the second trimester, your baby's organs mature and his or her skeleton starts to harden more. The baby swallows amniotic fluid and passes it out through his or her gut. Your baby’s kidneys start to work and pass small amounts of urine.

By 19 weeks, your baby is able to hear and is covered in fine hair called lanugo. If you have a scan at this stage, it's often possible to find out whether the baby is a boy or a girl; however , it may not be possible to tell for certain, for instance if your baby’s position on the day of the scan makes it difficult to see.

By the end of the second trimester, your baby has a chance of surviving if he or she is born prematurely, but would need intensive care.

Third trimester (28 to 40 weeks)

You
As your abdomen and breasts grow, you may get stretch marks. These are harmless and usually fade after your baby is born. Although many women try different moisturisers and lotions to prevent stretch marks, none have been proven effective.

You may find the extra weight you’re carrying makes you tired and you may get breathless as your expanded womb makes your lung capacity smaller.

You may have trouble finding a comfortable position to sleep in. Your baby's head drops down into your pelvis (engages) ready for delivery – for a first baby, this is usually towards the end of the pregnancy (around 37 weeks onwards).

This can cause pressure on your bladder, so you might need to pass urine more often. The head may not engage until labour if you have had a baby before.

Braxton-Hicks contractions – practice contractions – can start in the second trimester, but are much more common in the third. These can be mistaken for labour, but the difference is that real labour contractions are regular and usually cause some pain.

Braxton-Hicks contractions last only about 25 seconds and fade away rather than getting stronger over time.

Your baby

Your baby's lungs mature throughout the third trimester and by 32 weeks, he or she is much more likely to survive if born prematurely. Your baby makes breathing movements, even though his or her lungs don't work properly until birth.

Fat stores are laid down in preparation for birth. Your baby grows fine hair and fingernails, his or her eyes open and close and teeth may start growing under the gums.

Weight gain in pregnancy

You will put on weight during your pregnancy – the exact amount varies from woman to woman. Your midwife will usually weigh you at your first appointment. Unless you are very overweight or very underweight, your midwife probably won't weigh you again because it doesn't necessarily give any useful information about your developing baby.

If you're concerned about your weight gain, talk to your midwife or doctor. He or she will be able to tell you whether it’s too much or too little.

The weight you gain during pregnancy doesn’t mean that you’re getting fat. The extra weight is made up of:

• the developing baby, placenta and amniotic fluid

• the growth of your womb and breasts

• the increased blood in your circulation

• water retention

• essential fat stores