Antenatal care is the name of the particular form of medical supervision given to a pregnant woman and her baby starting from the time of conception up to the delivery of the baby. It includes regular monitoring of the woman and her baby throughout pregnancy by various means including a variety of routine regular examinations and a number of simple tests of various kinds.
Antenatal care is important because it helps to maintain the mother in good health during pregnancy, informs the parents about pregnancy, labour and child care and, in particular, it provides a means of detecting problems with the pregnancy at an early stage when the problems are treatable.
Routine antenatal care has dramatically changed this situation for the better. However, it must be remembered that pregnancy and childbirth are natural events that often proceed without problems in the vast majority of cases. The role of antenatal care and the tests that go with it are simply to monitor the pregnancy and to identify those few patients who may develop problems so that appropriate treatment can be instituted.
Antenatal care involves regular monitoring of the mother and baby by a physician, midwife or obstetrician (or by a combination of these professionals). Monitoring includes examination and a variety of tests, some routine and some for special circumstances. They can be physical tests (such as blood pressure measurement), blood tests and other types of test (for instance ultrasound examinations), details of which are outlined below.
The physical tests are carried out at the antenatal clinic, either at the hospital or physician surgery, and include measurement of the mother's blood pressure, her weight, and a test on a urine sample using a special analysis stick dipped into the urine. These monitor that the mother is well, that the baby is growing and that there are no signs of a blood pressure problem (pre-eclampsia) which sometimes occurs in pregnancy. The urine tests also make sure that the woman is not suffering from a urinary infection or has developed diabetes in pregnancy.
Sometimes at the first antenatal appointment the doctor may examine the woman's heart, breasts and also may perform a vaginal examination in some cases, to exclude any problems. Later on in pregnancy the mother's abdomen is also examined to check the position of the baby within the womb, to make sure the baby is growing satisfactorily and the doctor also usually listens for the heartbeat.
A variety of blood tests are done at different stages of the pregnancy to check on the mother's health and to avoid problems for the baby. At the start of pregnancy the following tests are usually done:
- A full blood count (FBC): This is a simple test to ensure that the mother is not anaemic or deficient in iron. Most women become slightly anaemic in pregnancy but some may require iron supplements if the anaemia becomes too severe since otherwise they are likely to feel extremely tired. They may develop further problems if they were to lose a lot of blood during childbirth. This test is often repeated at various stages during the pregnancy.
- Blood group: The mother's blood group is checked in the event of her requiring blood during childbirth and is tested for the presence of any special antibodies (factors in the mother's blood) which may harm the baby.
- Rhesus factor: This is a part of the blood group test. Everyone is either rhesus positive or rhesus negative. It is an important test because if the mother is rhesus negative but has a rhesus positive baby in her womb, antibodies could enter the baby's blood which might cause the baby to become quite unwell before or after birth. These used to be called 'rhesus babies'. If the mother is found to be rhesus negative a further test is done later in pregnancy to ensure that these antibodies have not occurred. After the birth the mother is given an anti-D injection which prevents antibodies being made in the blood, causing problems in subsequent pregnancies.
- Rubella immunity test: Most women are immune to rubella (also known as German measles) but this blood test is done to check that immunity is still present. It is important because if rubella is contracted during the early stages of pregnancy the baby may be born with deafness, blindness or other problems. Unfortunately the immunisation cannot be given while the mother is actually pregnant. If this test shows she is not immune, she will be given information about avoidance of contact with rubella and also what to do if she does come into contact with someone who has it. She will also be recommended to have the rubella immunisation after her baby is born so that her immunity is assured during any subsequent pregnancies.
- Syphilis test: At the moment every woman has a blood test for syphilis. Positive results occur very rarely, but the test is carried out because it can be treated in pregnancy; if it remains untreated it could result in the baby being seriously affected.
- Hepatitis B: This test is now becoming a routine antenatal test to see if the woman has ever been infected with the hepatitis B virus. In the unusual case of it being positive, the mother is given advice and extra care to try to prevent the disease from being transmitted to the baby.
- Triple test: This is usually performed between the 16th and 18th weeks of pregnancy and has mostly replaced what used to be known as the 'spina bifida test' (also known as the alpha foetoprotein test). The triple test measures the level of three hormones in the woman's body and helps to screen for two conditions; spina bifida (where the baby is born with a deformity of the spine which can cause paralysis) and Down's syndrome (sometimes known as mongolism). In the unusual situation where the triple test indicates a relatively high chance of one of these abnormalities occurring, the woman will be offered further tests such as amniocentesis (see below) to help further identify whether or not these abnormalities have occurred.
The triple test has recently come in for some criticism on occasions from women who have had abnormal triple test results followed by the amniocentesis test which has shown a healthy baby. This highlights the disadvantages of some screening tests i.e. that they may cause anxiety in cases where the pregnancy is, in fact, normal. The main problem with the triple test is that it gives a risk score (for example 1 in 12,000) of having a Down's syndrome baby. When the risk score is as low as about 1 in 250 or so the woman is usually offered amniocentesis even though she has a 249 to one chance of having a normal baby. This can cause a great deal of anxiety to 249 women for the one woman in whom an abnormality is detected.
At the moment there is no easy solution to this problem although a pregnant woman always has the choice not to have any test which she does not want as long as she has had all the information with which to make this decision.
An ultrasound scan of the baby is another routine test which is offered. High frequency sound waves are directed into the womb through a probe which is placed on the mother's abdomen. It provides very good images of the baby and has transformed antenatal care because it can give the doctors a great deal of useful information which is otherwise difficult to obtain. It is quite common for a woman to have two or more scans during the course of her pregnancy; one early on (at about 12 weeks' gestation) in the pregnancy to confirm the baby's estimated date of delivery and a later one (at about 16 weeks) to examine the baby in more detail in order to exclude certain abnormalities including spina bifida.
An ultrasound scan can also provide a lot of other useful information such as the position of the placenta (afterbirth), whether or not there is more than one baby, whether the baby is growing satisfactorily and also if there are any cysts on the ovary, or fibroids (benign growths on the womb) which may interfere with childbirth.
In certain circumstances various other tests may be done as additional checks on the baby:
This test is usually only done if the doctor feels that there is sufficient chance of the mother having a baby with an abnormality of the chromosomes (for instance Down's syndrome) or some other genetic disorder. It involves a needle being inserted through the mother's abdominal wall into the womb under ultrasound guidance usually between the 15th and 18th week of pregnancy. Some of the fluid surrounding the baby (the amniotic fluid) is removed and examined. This allows the specialist to examine the baby's chromosomes (genes) to check that they are normal. It will also mean that the doctor can tell for certain whether the baby is a boy or a girl which can sometimes be important in some inherited diseases.
Amniocentesis does carry about a 1% risk of causing a miscarriage and therefore the woman will be informed of the reason for the amniocentesis and the pros and cons of having this procedure. Sometimes this can be a difficult decision to make in view of the, albeit small, risk of causing a miscarriage. The expectant mother should not be afraid to ask any questions that will help her and her partner to make this decision.
This involves the specialist obtaining a sample of the placenta at about 10 weeks of pregnancy using a special needle inserted into the womb under ultrasound guidance. The tissue removed is examined in the same way as an amniocentesis test. This test is also used to exclude chromosome abnormalities but because it can usually be carried out earlier in the pregnancy than an amniocentesis, a woman could have an earlier abortion if the baby is found to be abnormal. However, this test carries a 3-5% risk of causing a miscarriage.
Sickle cell disease and thalassaemia are blood disorders which are found more commonly in certain races such as Africans and Afro-Caribbeans (sickle cell disease), and Mediterranean, Cypriots, Pakistanis and Indians (thalassaemia). Women of these racial groups may have a special blood test to detect these disorders which can cause anaemia, or problems for the baby who may inherit the disorder.
Some women may wish to have, or be advised to have, a blood test for HIV (AIDS) especially if they are in a high risk group for contracting the condition. These include women who have been drug abusers or the sexual partner of a drug abuser, those who have had intercourse with a man who has had sex with another man, prostitutes and those women who have been a sexual partner of someone known to have AIDS or HIV. Also in many areas women are being routinely tested for HIV as part of their antenatal blood tests although they will be informed that this test is to be done.
A woman who is HIV positive can transmit the virus to her baby either through the placenta, during childbirth or through breast milk. Therefore it is important for the baby's health that her HIV status is known because steps can be taken to reduce the chance of transmission to the baby. Delivering the baby by caesarean section has been shown to reduce the chance of transmission to the baby by 50%. However, despite the fact that this test is a simple blood test anyone considering having an HIV check should discuss the implications with a trained professional (such as a doctor) first.
There may be other tests which a woman has in pregnancy for special circumstances relating to her situation but it is important to remember that almost all pregnancies progress without any major problems and result in a healthy baby.
Toxoplasmosis and listeriosis are infections which, if contracted by a non-pregnant woman, cause very few, if any, signs of illness. However, in the rare instance of a pregnant woman developing listeriosis or toxoplasmosis they can result in miscarriage, stillbirth or severe illness in the newborn baby. Listeria is found in soft cheeses, blue-veined cheeses, pate and certain cook-chill foods. Toxoplasmosis can be found in raw meat or in the faeces of cats. It is therefore advisable for women to avoid digesting or coming into contact with these things during pregnancy. If a woman has concerns, her doctor may agree to carrying out specialised blood tests to see if she has developed the illness whilst pregnant. However these diseases are rare.