Common Pregnancy Disorders

The vast majority of pregnancies proceed with few real problems, normally involving only irritations and discomfort. However, it is important to be aware of certain signs and symptoms because in the unlikely event that they should occur, early diagnosis is often vital to prevent serious complications.

Vaginal bleeding

Vaginal bleeding in early pregnancy often, but not always, signals the start of a miscarriage. Miscarriage occurs in one in every ten pregnancies. A threatened spontaneous abortion (the terms miscarriage and spontaneous abortion have a similar meaning in medical parlance) may present itself as very slight bleeding or the bleeding may be as heavy as a normal period. It may be associated with backache or abdominal pain similar to period pain, and it is more likely to occur at around the time a period would have arrived had the pregnancy not begun. The blood lost initially during a threatened miscarriage is usually bright red or pink, changing later to a brown discharge as the flow decreases.

Women with threatened miscarriages are usually advised to remain in bed at least until the discharge has completely stopped. They are also advised to rest at about the time their next period would have been due, and to avoid sexual intercourse until a doctor considers it safe.

Bed rest is often effective in preventing a threatened miscarriage and if the pregnancy continues it is unlikely that the baby will be adversely affected by this episode. In some cases miscarriage is inevitable because the foetus has already become separated from the placenta. The bleeding becomes heavier and brighter in colour and the uterus contracts to expel its contents. This leads to pain, which varies in intensity according to the stage of the pregnancy. The expelled material may be required for a doctor’s examination because it may provide clues as to why the miscarriage occurred. The doctor will also want to establish whether the whole of the foetus and the placenta have been expelled (a complete abortion), otherwise complications such as heavy bleeding and infection may occur subsequently. If some tissue has been retained (an incomplete abortion), a minor operation may be necessary, such as dilatation and curettage (D and C), to scrape or suck away the lining of the uterus.

In some cases the foetus dies in the uterus and is not immediately expelled (a missed abortion). The symptoms of a missed abortion are very difficult to distinguish from those of a threatened one. A woman who has a threatened abortion and then notices that the symptoms of pregnancy, such as nausea and breast tenderness, have disappeared should tell her doctor, who may arrange for an ultrasonic examination to observe whether the foetal heart is still beating. Once a missed abortion has been diagnosed, the uterine contents can be removed by D and C.

The cause of a miscarriage in early pregnancy cannot be determined in at least half of the cases, and a woman may have more than one. In general one could say that even if only a tiny abnormality is present somewhere in the delicate balance between motherplacenta-child, nature will be apt to react to this with a shedding of the product. This can be seen as a mechanism of nature to maintain a healthy species.

Possible causes for an abortion include chromosomal abnormalities, a defect in early development of the embryo or faulty implantation. And, in the mother, a hormonal imbalance or the presence of an intrauterine contraceptive device. Intercourse, however, cannot cause an abortion.

Many therapies have been tried to prevent miscarriages, but at this moment the conclusion should be that no therapy is wholly effective. In the past, some therapies given to prevent abortion, although effective at the time of use, were subsequently found to be harmful.

The hormonal DES treatment, given in the 1950s, was later proved to increase the risk of vaginal cancer in female offspring.

The most sensible way to act in cases of vaginal bleeding is avoiding strain, taking enough rest and refraining from intercourse for a time.

Slight bleeding in early pregnancy may have causes other than miscarriage, such as a cervical erosion, or a raw area on the neck of the uterus. This can cause blood loss, but without pain. Bleeding accompanied by excruciating pain may indicate an ectopic pregnancy.

Once the foetus has reached a stage where it is capable of independent existence, at about 28 weeks, vaginal bleeding is called antepartum haemorrhage. It may indicate placental problems or signify the start of premature labour. In either case, medical assistance is urgently required.

Ectopic pregnancy

An ectopic pregnancy is one in which the fertilized egg embeds itself somewhere other than in the uterus. In most cases instead of travelling along the Fallopian tube to embed itself in the uterine wall, the egg stays in the tube where it begins to develop. In comparison to the uterus, the Fallopian tube is a relatively tiny structure, the blood supply to which falls short in only a few weeks. The embryo usually dies as a result of this and loses contact with the tube, when bleeding occurs. In some cases the developing placenta grows through the tube wall – this may cause severe blood loss into the abdominal cavity. Abdominal cramps result, but the main symptom is the sudden onset of severe pain on one side of the lower abdomen, usually followed by vaginal bleeding. It is essential to get medical help quickly, because surgery is needed to stop the haemorrhaging and, usually, to remove the affected tube and the embryo it contains. It is rare for an ectopic pregnancy to last for more than eight weeks without pain or bleeding.

Women who have had a previous ectopic pregnancy or tubal infection, and those fitted with an intra-

uterine contraceptive device, run a slightly higher than average risk of ectopic pregnancy. In very rare cases the egg embeds itself somewhere in the abdominal cavity. It may take more time until the first symptoms appear, but it is no less serious.

Placental problems

Vaginal bleeding in late pregnancy (antepartum haemorrhage) may have several causes. A slight blood-stained discharge may indicate that labour is about to begin, and this can be distinguished from the bright-red bleeding that occurs if either of two placental conditions – placenta praevia or abruptio placentae – is present.

In placenta praevia (which occurs in one in every 100 to 200 pregnancies) the placenta develops in the lower part of the uterus, partly or completely covering the cervical opening. In this condition it has no support at the site of the cervical opening (ostium) and will tend to become separated from the uterus towards the end of pregnancy, resulting in bleeding. A diagnosis of placenta praevia can be confirmed using ultrasound, and admission to hospital is necessary. In severe cases, to avoid the baby’s blood supply being damaged during delivery, a Caesarean section may be performed.

In abruptio placentae the placenta, which is in the normal position at the top of the uterus, separates prematurely from the uterine wall, putting the baby’s blood supply at risk. Sudden severe pain and vaginal bleeding eventually result as blood works its way round the foetal and maternal membranes. This very rare condition often occurs in conjunction with high blood pressure. An abruptio placentae immediately stops the blood supply to the foetus.

If diagnosed very early, a Caesarean section may be performed, but in general this condition gives little chance for the child.

Hydatidiform mole

A hydatidiform mole results from abnormal development of the chorionic villi* which normally form the placenta. In this very rare complication, which mimics pregnancy, only the placental tissues develop and they do so to an excessive extent. The cystic development of the chorionic villi has been likened in appearance

to a bunch of grapes. The only symptom may be irregular vaginal bleeding. A large quantity of the pregnancy hormone HCG is produced by the mole. That is why pregnancy symptoms are present to an even greater extent than normal. The uterus is often larger than expected but in examination no signs of life are present. The diagnosis can be confirmed by ultrasound which will clearly demonstrate the absence of a foetus.

The contents of the uterus will be removed by a D&C operation. Because in rare instances a tumour called choriocarcinoma may develop following a hydatidi-

form mole, the woman’s blood and urine will be monitored for hormonal changes for a period of about two years, during which time pregnancy should be avoided. Provided a choriocarcinoma is detected at an early stage, cure rates using chemotherapy treatment, for example, are very high.

Polyhydramnios

Polyhydramnios, or simply hydramnios, which is an excessive amount of amniotic fluid, often has no discernible cause. Chronic polyhydramnios is usually detected for the first time at about 30 weeks when an excessive amount of fluid has been building up for some time. It does not cause pain, although the size of the uterus, which is larger than expected for the duration of the pregnancy, may be uncomfortable. The condition may be a sign of congenital abnormality which can usually be confirmed by ultrasonic examination.

Because the main symptom of polyhydramnios – the larger than expected uterus – is one of the normal indications of a multiple pregnancy the condition is usually detected when an examination is made to diagnose whether more than one foetus is present. Premature labour is more likely if polyhydramnios is present although bed rest often reduces this risk. Labour may be prolonged and uterine contractions weak; in addition, the baby may not descend to the correct position for birth if it is surrounded by too much amniotic fluid. Expectant mothers with this condition, if in great discomfort and near term, may have labour induced early.

Acute polyhydramnios, which is very rare, occurs

earlier in pregnancy than the chronic condition described above and is often associated with identical twins.

It used to be a major cause of maternal and perinatal mortality.

Pre-eclampsia

Swollen hands or ankles, together with high blood pressure and protein in the urine indicate the presence of pre-eclampsia. There is also the risk of developing the more severe form, eclampsia, with its associated maternal convulsions and sometimes loss of consciousness. Pre-eclampsia can be present even if the mother reports that she feels perfectly well. Occurring mainly in the last three months of pregnancy, it is often only detected when routine check-ups are being made. There is often a sudden above-average weight gain caused by salt and water retention.

The development of severe pre-eclampsia or consistantly raised blood pressure will probably require admittance to hospital for bed rest, which is important in keeping the condition under control. Drugs may also be given to lower the blood pressure. If these measures fail to bring the blood pressure down, labour may be induced a few weeks early or, if necessary, a Caesarean section may be performed. Pre-eclampsia affects about one in 20 pregnancies. Its exact cause is not known and, because most women have the disorder diagnosed and treated at an early stage, eclampsia itself has become rare.

Hyperemesis gravidarum

Hyperemesis gravidarum is a rare condition of pregnancy in which vomiting is so severe that no food or fluids can be retained, and hospital treatment is required. Drugs may be given to control vomiting, and fluids, electrolytes and nutrients lost during repeated vomiting are replaced via an intravenous infusion. The vomiting is usually controlled within a couple of days.

Rhesus factor and pregnancy

In addition to the A-B-0 blood group system it was found in 1937 that a rhesus group existed as well. About 85 per cent of people are rhesus-positive and 15 per cent rhesus-negative. This rhesus factor can cause trouble in pregnancy but only if the mother is rhesus-negative.

It is not possible for foetal and maternal blood to keep fully separated during pregnancy. If the baby has a positive rhesus-factor, the mother, if she is rhesus-negative, will produce antibodies against these foetal blood cells that have entered her blood circulation. If she gets pregnant a second time, and if the baby is again rhesus-positive, these antibodies, which pass through the placenta, will break down the baby’s red blood cells.

Fortunately it is possible to keep things under control and provide adequate therapy in cases in which rhesus-incompatibility* is found. The first antenatal check-up includes a blood test which will indicate the rhesus-factor of the mother. If a positive rhesus-factor is found, no problems will arise. Rhesus-negative women however are carefully monitored for antibodies at the antenatal clinic at about the 32nd week of pregnancy. If antibodies are present, this can be the result of a first pregnancy (particularly if a Caesarean section was performed); any blood transfusion with rhesus-positive blood; an abdominal traumatic event during pregnancy; or bleeding in the third trimester. When antibodies are present, this means the child may be affected when it has rhesus-positive blood. Amniocentesis is necessary to determine whether and to what extent it is affected.

The amniotic fluid sample is examined for its bilirubin concentration. The more blood that has been destroyed, the higher the bilirubin concentration. If the situation for the baby is regarded as serious, a Caesarean section can be considered, or a foetal blood transfusion can be performed. A baby born with antibodies against its own blood cells will be anaemic.

In addition it will become jaundiced some hours after delivery. If this is severe a blood transfusion may be necessary.

If at the 32nd week no antibodies are present in the blood of a rhesus-negative mother, nothing has to be done until after the birth. A blood sample is taken from the umbilical vessels just after birth to determine the rhesus factor of the child. If this is negative, no antibodies can be formed because the mother has the same rhesus factor.

If however the baby’s blood shows a positive rhesus factor, the mother has to be treated with ‘anti-Dglobulin’ within 48 hours. This globulin attacks any of the baby’s red blood cells that might have entered the maternal blood circulation.

The production of antibodies in the mother is thus prevented, and no problems should arise in the next pregnancy.