Most pregnant women only experience the minor complications of pregnancy, but for a minority more serious problems occur.

In extreme cases, these can result in the death of the baby and, very rarely in developed countries, that of the mother.

Problems range from failure of the embryo to implant in the womb, leading to miscarriage, to rupture of the placenta and pre-eclampsia.

The foetus can also develop problems in the womb, including genetic defects.

Blood tests are offered in the early stages to screen for Down’s syndrome, spina bifida and other chromosomal abnormalities.

The tests - for alpha-fetoprotein levels - cannot predict if the baby will have an abnormality.

They only predict probability. If probability is high, the woman will be offered further more accurate tests, including amniocentisis.

This involves sticking a needle into the womb to take a sample of amniotic fluid. It carries a small risk of miscarriage.

Ultrasound scans can also detect abnormalities as well as slow-growing foetuses, which may be the result of poor blood supply or other complications.

To minimise the possibility of the foetus developing spina bifida, woman are advised to take folic acid supplements in the months leading up to conception and the first three months of pregnancy.

Miscarriage:

Miscarriage - when the pregnancy is terminated before the sixth month - is estimated to occur in between 10 to 20% of pregnancies, but this may be an underestimate as many women may miscarry before they are even aware they are pregnant.

Miscarriage usually happens in the first three months.

Early miscarriage is mainly due to the foetus failing to develop normally.

Later miscarriage is more likely to be the result of the placenta not functioning properly or a weak cervix.

Symptoms include bleeding, but this is not always the case and about half of all women who bleed in the early stages of pregnancy do not go on to miscarry.

Some women continue to have a brief period during their pregnancy and bleeding may also not be related to the foetus at all but could be caused by lesions in the vagina or cervix.

Ectopic pregnancy:

Other implantation problems include ectopic pregnancy where the fertilised egg becomes embedded outside the womb.

Ectopic pregnancy is now the most common cause of maternal death in the first three months of pregnancy in the west and it has been increasing steadily in the UK in recent years.

This is probably because other causes of maternal death have decreased due to better care.

However, 90% of cases are now diagnosed in the early stages before life-threatening complications arise.

The reasons for ectopic pregnancy are unclear, but research suggests damage to fallopian tubes caused by infections, such as sexually transmitted diseases, could be a factor.

Symptoms include severe pain and bleeding. The woman may not know she is pregnant.

Because the condition is being diagnosed earlier due to more advanced technology, it often does not cause lasting damage and the woman can go on to have a normal pregnancy afterwards.

Pre-eclampsia:

Pre-eclampsia - or pregnancy-induced hypertension - is thought to occur in 10% of pregnancies and is the commonest cause of maternal death in the UK, killing around 10 women a year.

It also leads to the death of some 1,000 babies a year.

Symptoms include high blood pressure, fluid retention and protein in the urine.

Blood pressure and urine are now regularly checked throughout pregnancy.

Pre-eclampsia usually occurs towards the end of the pregnancy and the effects can be felt for some days after the birth.

Some women are thought to have a genetic predisposition to it.

Women are more likely to suffer from the condition in their first pregnancy and most do not go on to experience it again in subsequent pregnancies.

The causes of pre-eclampsia are unclear, but research suggests it may be linked to an immune reaction to the foetus or the placenta.

If the condition is serious, women may be advised to rest or take drugs to lower their blood pressure and, in some cases, an early caesarean or induction may be performed.

Placenta praevia and placenta abruptio:

Both these conditions result in bleeding in the later stages of pregnancy and can be life-threatening for the baby, but are relatively rare.

Many pregnant women are told they have a low-lying placenta.

In most cases this moves upwards during the course of the pregnancy.

However, in a small proportion of cases, the placenta remains near the opening of the cervix and can lead to bleeding and potentially to the loss of the baby.

This is known as placenta praevia. A caesarean is usually necessary and, in severe cases, women may require a blood transfusion.

With placenta abruptio, the placenta becomes detached from the lining of the womb, resulting in severe pain and bleeding which may flow down and out through the vagina or upwards and in the foetus being starved of its oxygen supply.

With both conditions, the causes are unclear and recurrence in a subsequent pregnancy is unlikely.

Women who bleed in later pregnancy are advised to contact their hospital immediately.

Pregnancy wreaks havoc on the female body.
As well as pluses such as thick hair and a ‘blooming’ complexion, it pushes organs out of place and floods the body with hormones.

Discomfort from having your stomach in your chest and other organs in unaccustomed places does not usually occur until the final stages of pregnancy when the baby is bigger, but hormonal changes may be evident from the first moment, causing sudden mood swings and making the victim feel as if she is on an emotional rollercoaster.

Many of the minor problems of pregnancy can be lessened through healthy eating - five portions of fruit and vegetables a day - and exercise and many are the first signs that a woman is pregnant.

They include:

• feeling sick or going off food that the woman previously enjoyed
• a metallic taste in the mouth
• constipation
• fatigue
• tender, larger breasts

Many of these last the whole pregnancy and are accompanied by other problems.
Few women escape at least one of the following:

Morning sickness:

Many theories exist as to why some women suffer terribly from morning sickness and others appear to escape unscathed, but a major factor is likely to be the body reacting to hormonal changes.

The condition, which can range from feelings of nausea to continuous vomiting, can occur at any time of the day or all through the day.

For some women it lasts throughout the pregnancy, but for most who have it usually fades after the third month.

Stress and diet, particularly fatty or spicy food, are thought to play a part.

Many women fear that, if they cannot eat because of sickness, they will harm the foetus, but research shows this to be unfounded.

The person who suffers is the mother.

As one doctor put it: “The baby will survive.”

However, the condition may be offset by eating small amounts regularly, drinking lots of fluids, resting exercising and avoiding foods that make the woman feel nauseous.

Doctors recommend that women who suffer from morning sickness have something to drink, such as sweet tea, and some dry toast before getting up.

If a woman cannot keep any food down, she should consult her GP.

Constipation and haemorrhoids:

The bowel absorbs more fluid during pregnancy and food moves slower down the intestines.

This can lead to constipation which can in turn trigger haemorrhoids - protrusions from the anus which bleed and can be painful and itchy.

Pregnancy hormones which relax the veins may also contribute to haemorrhoids.

Women who have to take additional iron may find that this worsens the problem.

Pregnant women with constipation are discouraged from taking laxatives.

Instead doctors recommend eating lots of fruit and vegetables, exercising regularly, avoiding standing still for long periods and drinking plenty of fluids.

There are also creams and suppositories on the market which lessen the irritation caused by haemorrhoids.

They can also be pushed back into the anus with lubricating jelly.

Most clear up soon after the birth of the baby.

Varicose veins:

These are another consequence of hormonal changes which relax the veins, slowing blood flow.

They can be painful and itch and occur in the legs and vaginal area.

Usually the ones in the vaginal area disappear after birth, but those in the legs may not totally vanish.

Some women appear to have a genetic disposition towards varicose veins.

The following can lessen the problem:

• regular exercise
• avoid long periods standing still, sitting with crossed legs and wearing tight-fitting underwear
• sit and sleep with your feet up
• avoid excessive weight gain during pregnancy
• use ice packs

Cramp:
Cramp - sudden muscle spasms - is thought to affect up to half of all pregnant women.

It mostly occurs at night and can be extremely painful.

Many theories exist as to the cause, including mineral deficiencies and poor circulation, but none has been totally proved.

Massaging the affected area - often the feet - can help, as can flexing the foot and regular exercise.

Indigestion and heartburn:

Indigestion can be due to hormonal changes in the early stages of pregnancy.

In the later months, it is likely to be a result of the foetus pushing the stomach upwards.

It can be avoided by eating little and often, instead of big meals, avoiding fatty and spicy food and sitting up straight when eating.

Heartburn is more painful than indigestion and is the result of the relaxation of muscles at the stomach opening.

This causes excess acid in the stomach.

It is most likely to occur when lying flat so doctors recommend sleeping with feet propped up and avoiding food for two or three hours before going to bed.

Pregnant women should consult their GP, midwife or chemist before taking any indigestion remedies as they could affect the foetus.

Backache:

Ligaments become looser during pregnancy in preparation for labour, but this can put more pressure on the lower back and pelvis, causing backache.

This is likely to increase in the later stages of pregnancy as the foetus gets heavier.

This can be lessened by avoiding lifting heavy objects, keeping the back straight when lifting objects, wearing flat shoes and sitting with the back well supported.

Exercises which involve arching the back can also help.

Other common problems of pregnancy include

• faintness (due to poor blood circulation to the brain)
• needing to urinate often (caused by the baby pressing on the bladder)
• bleeding gums (due to hormonal changes)
• stretch marks, swollen ankles, fingers and feet (due to water retention)
• vaginal discharge (usually clear and white, but it can be itchy if there is an infection, this is most likely to be thrush)
• headaches

Women who suffer from severe headaches should consult their GP as this could be a result of high blood pressure.

Weeks 1-4
Fertilisation occurs and a ball of quickly multiplying cells embeds itself in the lining of the uterus.
In the UK pregnancy is calculated from the first day of the woman’s last period so for as much as three weeks of this first month she might not be actually pregnant. When fertilisation does occur the tiny mass of cells called a blastocyst at this stage embeds itself in the lining of the womb which is already thickening to support it.

Week 5
The mass of cells is developing fast and becomes an embryo. For many women the first sign of pregnancy is a missed period.
Shopbought tests are considered largely reliable so the mother-to-be does not have to have her pregnancy confirmed by her GP. If a first test is negative a second one a few days later may prove positive as hormone levels in the urine rise.

Week 6
The embryo officially becomes a foetus. It is about the size of a baked bean and its spine and nervous system begin to form.
The foetus already has its own blood system and may be a different blood group from its mother. Blood vessels are forming in what will become the umbilical cord and tiny buds which will become limbs appear.

Week 7
The baby´s heart is beginning to develop. Morning sickness and other side effects of early pregnancy may take hold.
Around this time many women find they experience the side-effects of early pregnancy including needing to urinate more often nausea and vomiting and feeling a bit weepy and irritable. All medication including supplements need to be carefully checked as the foetus is undergoing vital development in the first 12 weeks. If the woman has not told her GP or community midwife she is pregnant yet now is a good time to do so.

Week 8
It is quite common to have a first scan at this stage if the woman has had a previous miscarriage or bleeding.
An early scan is often done through the vagina and is used to check the pregnancy is not ectopic. It should show up the baby´s heartbeat. The nervous system is also developing rapidly especially the brain. The head gets bigger and eyes form under the skin of the face. The foetus’ limbs are growing and look more like arms and legs. All internal organs are developing and becoming more complex.

Week 9
The foetus is about 5cm long with its head tucked onto its chest. It has most its major organs and eyes and ears are developing.

Week 10
A scan at 10-13 weeks is recommended to pin down the date of the pregnancy.

Week 11
The umbilical cord is fully formed providing nourishment and removing waste products. The foetus looks fully human now.

Week 12
By this week the threat of miscarriage is much reduced. Many women announce their pregnancy to friends and colleagues.
The foetus is growing in length much more quickly by now it is about eight cm long and weighs about 60 grams. The placenta is now wellformed though it’s not yet doing its full job it takes over fully in week 14. The mother is likely to have her first scan this week.

Week 13
The womans uterus is becoming larger and is starting to rise out of the pelvis. The foetus can move its head quite easily.

Week 14
Third of the way through. The average pregnancy lasts 266 days or 280 days from the first day of last period.

Week 15
Screening for Downs syndrome is offered about now. A simple blood test is carried out first then further tests may be offered.
On the basis of the blood test results the woman may opt for a Chorionic Villus sample or an amniocentesis which would diagnose Down’s syndrome or other chromosomal abnormalities. However these diagnostic tests have a small risk of subsequent miscarriage. An alternative to blood tests is a nuchal translucency scan a new scan offered by some larger hospitals. But again an amniocentisis would be required for firm diagnosis.

Week 16
The foetus now has toe and finger nails eyebrows and eyelashes. It is also covered with downy hair.
The hair that will cover the baby until the last week or so of pregnancy - called lanugo - starts to form. This hair is very fine more like down and it probably serves as some form of insulation and protection for the skin.

Week 17
The foetus can hear noises from the outside world. By this stage the mother is visibly pregnant and the uterus is rising.

Week 18
By this stage the foetus is moving around a lot - probably enough to be felt.

Week 19
The foetus is now about 15-20cm long and weighs about 300g. Milk teeth have formed in the gums.

Week 20
Half way through pregnancy now. Almost all mothers are offered a routine scan. The foetus develops a waxy coating called vernix.
The scan can show the foetus in fine detail and often reveal if the baby is a boy or a girl. However not all hospitals offer to tell parents the sex of the child - and not all parents want to know.

Week 21
The mother may feel short of breath as her uterus pushes against her diaphragm leaving less space for the lungs.
The mother may be offered another ultrasound scan around this time. The scan can check the baby´s spine internal organs and growth are normal.

Week 22
Senses develop: taste buds have started to form on the tongue and the foetus starts to feel touch.

Week 23
The skeleton continues to develop and bones that form the skull begin to harden - but not fully.

Week 24
Antenatal checkup and scan to check the baby´s position. A baby born this early does sometimes survive.
A baby born at 24 weeks may possibly survive but it would have severe breathing difficulties as its lungs would not be strong enough to cope. It would also be very thin lightweight and susceptible to infections.

Week 25
All organs are now in place and the rest of the pregnancy is for growth. Preeclampsia is a risk from here onwards.
This potentially fatal condition causes high blood pressure protein in the urine and swelling caused by fluid retention. The causes are unclear but research suggests it may be linked to an immune reaction to the foetus or the placenta. If the condition is serious women may be advised to take drugs to lower their blood pressure and in some cases an early caesarean or induction may be performed. Serious complications of pregnancy

Week 26
The foetus skin is gradually becoming more opaque than transparent.

Week 27
The foetus measures about 34cm and weighs about 800g.

Week 28
Routine checkup to test for preeclampsia. Women with Rhesus negative blood will also be tested for antibodies.
If the mother has Rh negative blood but the baby is Rh positive she can develop antibodies to her baby´s blood during labour. This is not a problem in the first birth but can affect subsequent pregnancies and result in stillbirth. Fortunately treatment is simple and effective. BBC Health: Ask the doctor - Rhesus disease

Week 29
Some women develop restless leg syndrome in their third trimester.
This is sensations such as crawling tingling or even cramps and burning inside the foot or leg - often in the evening and at night disturbing sleep and making the mother feel she needs to get up and walk around. No-one knows what causes this harmless but irritating condition.

Week 30
Braxton Hicks contractions may begin around now. They are practice contractions which dont usually hurt.
These are irregular, painless contractions which feel like a squeezing sensation near the top of the uterus. If contractions become painful or occur four times an hour or more, the woman should call a doctor as she may be in early labour.

Week 31
The foetus can see now and tell light from dark. The mother´s breasts start to produce colostrum about now
This high calorie milk is produced by the mother to feed the baby for the first few days after birth before normal milk starts.

Week 32
Another antenatal appointment. The foetus is about 42cm and weighs 2.2kg. A baby born now has a good chance of survival.

Week 33
From now the baby should become settled in a head downwards position. A midwife can help to move it if necessary.

Week 34
The mother may find it more difficult to eat full meals as the expanded uterus presses on her stomach.

Week 35
If the mother has been told she may need a planned caesarean, now is a good time to discuss it further.

Week 36
The baby´s head may engage in the pelvis any time now.

Week 37
The baby´s lungs are practically mature now and it can survive unaided. The final weeks in the womb are to put on weight.

Week 38
Babies born from this week onward are not considered early.

Week 39
Another ante-natal appointment. The mother has reached her full size and weight by now.

Week 40
In theory the baby should be born this week. The mother´s cervix prepares for the birth by softening.

Week 41
First babies are often up to a week late but if there are signs of distress to mother or child the birth will be induced.

Symptoms of pregnancy include the following:

• Breast tenderness
• Nausea, vomiting, or both
• Missing a period or having an abnormal period
• Weight gain
• Breast enlargement, nipples darkening, or breast discharge
• Urinating more frequently than usual
• Fetal movement (after 20 weeks for new mothers)