Bleeding in pregnancy
Doctors divide pregnancy into thirds (called trimesters) because the significance of symptoms such as vaginal bleeding varies according to how far advanced the pregnancy is. This fact sheet contains information about some of the possible causes and treatment of vaginal bleeding throughout pregnancy.
Bleeding in early pregnancy
Bleeding in early pregnancy?
Vaginal bleeding in early pregnancy is a very common symptom. Estimates suggest that it occurs in at least 20 per cent of pregnancies but it is almost certainly more frequent than this because often women will not report a small amount of 'spotting' to their general practitioner (physician). Also bleeding can vary from heavy vaginal bleeding to a small amount of light red loss or even brownish vaginal discharge (which usually means that the amount of bleeding is very slight).
There are several possible causes that, as you will see below, include both very simple things that do not affect the mother or the pregnancy, and also more important causes. The more common causes are listed below, followed by an explanation of each one:
- cervical erosions and polyps
- vaginal infections
- implantation bleeding
- threatened or inevitable miscarriages
- ectopic pregnancies
- a molar pregnancy
Cervical erosion (also called 'cervical ectopy' by doctors) is a non-serious phenomenon where a red area appears on the cervix (the neck of the womb). Normally, the womb lining (the endometrium) stops just inside the cervix and therefore cannot be seen when a woman is examined with a speculum (an instrument introduced into the vagina, such as occurs when she is having a cervical smear). However, sometimes a small area of womb lining spreads onto the outer surface of the cervix and appears as a reddish patch on the outside of the cervix.
Cervical erosions are very common especially in women who are pregnant or on the oral contraceptive pill. They do not give any pain and are not dangerous but, since the tissue that causes them is liable to bleed, it is a cause of vaginal bleeding. The amount of bleeding caused by cervical erosions tends to be small and usually, but not always, follows intercourse.
Cervical erosion can be diagnosed using a speculum to observe the cervix. The doctor or nurse is able to see the characteristic appearance of a reddish patch on the cervix that is liable to bleed slightly when touched. Often cervical erosions will be left alone and not treated since they are of no harm to the woman. This is particularly true in a pregnant woman since the treatment (although simple) is likely to be more hazardous to the pregnancy than the condition itself. It is usually left alone and only treated if it continues to cause frequent vaginal bleeding following the birth of the baby. Often, however, the erosion will disappear spontaneously once the hormones related to pregnancy have returned to normal after childbirth.
If erosions are treated, this is usually done by 'cauterising' the surface of the cervix. This involves applying a special hot wire instrument or laser to the erosion that then disappears and is replaced by normal tissue.
Cervical polyps are similar to cervical erosions in that they are a non-serious cause of vaginal bleeding, although they are far less common. A polyp is a teardrop-shaped extra piece of tissue. In the case of cervical polyps they are seen emerging through the opening of the cervix when a doctor or nurse looks at the neck of the womb during an examination using a vaginal speculum. In most cases it is not known why they occur but they are not harmful to the mother or baby and are usually only discovered if they cause vaginal bleeding as a result of which the doctor will examine the neck of the womb using a vaginal speculum.
Cervical polyps do not necessarily need to be treated but are sometimes removed if they continue to cause vaginal bleeding. However, this procedure is almost always left until after the end of the pregnancy.
Occasionally infections can occur inside the vagina during pregnancy. By causing soreness and inflammation of the lining of the vagina, they can result in vaginal bleeding. In most cases the infection will not be serious. For instance, the most common vaginal infection in pregnancy is Candida (better known as 'thrush'). This is a yeast infection, which tends to cause a white vaginal discharge, vaginal itching and soreness but in severe cases, can cause the vagina to bleed. Thrush will not harm the pregnancy but it is usually treated, as it is unpleasant for the mother. Treatment is with vaginal pessaries or cream containing, for example, clotrimazole (Canesten) or nystatin (Nystan).
Other infections can occur, some of which are important to treat, such as one called beta haemolytic streptococcus, which has been linked to premature births and other problems that could affect the health of the newborn baby. Therefore, as part of the investigation of bleeding in pregnancy for which no cause can be found, the doctor or midwife may take a swab from inside the vagina. This collects a sample that is then examined in the laboratory for infections. Any infection found can then be treated appropriately. For instance, beta haemolytic streptococcus is usually easily treated with penicillin.
Implantation bleeding is the name given to a small amount of vaginal bleeding that occurs in early pregnancy. It often happens at about the same time as the first missed period at the beginning of a pregnancy and is thought to be due to blood being released as the fertilised egg embeds into the lining of the womb. It has no significance and therefore needs no treatment.
Miscarriages unfortunately occur in about 20 per cent of pregnancies. The causes of miscarriages are not fully understood. We do know that in about 60 per cent of cases the foetus either has a significant abnormality (which usually means it would not have lived even if it had reached the end of pregnancy), or no foetus was produced at all. This second situation is sometimes referred to as a 'blighted ovum' which means that the pregnancy consisted only of a gestation sac with no foetus inside it. In most of the remainder there is an abnormality of the chromosomes (a serious genetic problem). This means that about 90 per cent of the time, the miscarriage seems to have been for a reason that could be explained as nature's way of filtering out problems early on in a pregnancy.
Doctors give names to different stages in the process of a miscarriage but these are more relevant to the medical treatment than they are to the woman who is bleeding in pregnancy. However, it may be useful to understand these terms in case they help to explain a situation relating to your own circumstances. It is worth mentioning that the medical profession uses the word "abortion" for the ending of a pregnancy before the 20th week, whether it is as a result of a miscarriage or as a procedure done at the request of the mother (which is what most people think of as an abortion).
A threatened abortion is where there is bleeding in early pregnancy from inside the womb (ie not due to a cervical erosion or vaginal cause) which is enough to threaten the wellbeing of the foetus. At this stage there is no way of predicting whether or not it will progress to a miscarriage.
An inevitable abortion is where the vaginal bleeding is associated with an opening up of the cervix and the passage of what are called 'products of conception', ie foetal tissue. In other words a miscarriage is inevitable and cannot be prevented.
An incomplete abortion is where a miscarriage has happened but there are still some products of conception remaining in the womb, which need to be removed. This is carried out during a procedure called an ERPC (evacuation of retained products of conception) which is similar to a 'D and C' (dilatation and curettage) where the neck of the womb is widened and the womb is emptied using special instruments. ERPC is done under a general anaesthetic.
A missed abortion is where the mother thinks she is still pregnant but, when an ultrasound scan of her womb is done, it is discovered either that she has miscarried or that the foetus is already dead. In these cases, if there is anything still in the womb, the woman is taken to hospital for an ERPC in the same way as for an incomplete abortion.
Unfortunately, there is no treatment as such for a miscarriage. If a woman is bleeding in early pregnancy, an ultrasound scan is usually done to establish whether the foetus is still alive or not. If a heartbeat is seen, the woman is informed and treated in the same way as before with the usual antenatal monitoring. However, if the foetus is found to be no longer alive or the woman has already miscarried, she is treated as mentioned above depending on whether the miscarriage is complete or incomplete. In the case of a threatened abortion, bed rest is occasionally suggested although this has not been proven to make any difference to the outcome.
Women who have suffered a miscarriage often ask when they can start trying to conceive again. The answer is that they can start trying as soon as they feel able to do so although it is usually advised that they wait until they have at least one normal period as this will confirm that their system is back to normal, and will help the doctors to more accurately predict her estimated date of delivery.
If a woman has several miscarriages, investigations are sometimes done to see if a cause can be found. Some conditions can result in a woman having repeated miscarriages and knowledge of this may help the specialist to advise treatment that will make a subsequent pregnancy more likely to go to full term.
This is the most serious cause of vaginal bleeding in early pregnancy and is due to the foetus growing somewhere other than in the womb. Usually the fertilised egg travels down the fallopian tube (the tube leading from the ovaries, where the egg is produced, to the womb) and enters the main part of the womb where it embeds into the lining and develops into a baby.
In an ectopic pregnancy, the fertilised egg gets stuck in the fallopian tube, or in rare cases, travels the 'wrong way' out of the end of the fallopian tube, where it buries itself in the ovary or sometimes into the outside of the bowel. About nine in every thousand pregnancies result in an ectopic pregnancy and they are more common in certain women, for instance those who have scarring of the fallopian tubes either from having had surgery on the tubes at some time before the current pregnancy or from a past infection in the tubes. A condition called endometriosis can also lead to a higher risk of an ectopic pregnancy as can the presence of an IUCD (intra uterine contraceptive device, commonly known as a contraceptive 'coil').
The usual symptoms of an ectopic pregnancy are where a woman, who has just learned that she is pregnant, has had only one missed period and then experiences pain just to one side of her lower abdomen and develops some vaginal bleeding. However, these symptoms do not always occur and it is possible for an ectopic pregnancy to occur even before the woman is aware that she is pregnant and she may not experience any signs of vaginal bleeding. The danger is that the pregnancy continues to grow inside the fallopian tube, which eventually ruptures (bursts), causing a lot of internal bleeding.
An ectopic pregnancy is a potentially life threatening condition, so doctors are always on the alert if a woman who could be pregnant has low abdominal pain with or without bleeding. If an ectopic pregnancy is suspected, the woman will be admitted to hospital, where an ultrasound scan is usually done to establish if a pregnancy exists and if so, where it is growing. If doubt still exists, further investigations may be done. These include blood tests to accurately measure the hormones related to pregnancy (which continue to rise if a foetus is growing), and a laparoscopy (a procedure done under general anaesthetic where a special telescope is inserted into the abdomen to allow the gynaecologist to see inside the woman's pelvic cavity).
If an ectopic pregnancy exists, an operation is done immediately to remove it. Wherever possible the surgeon will try to repair the damaged fallopian tube but this is not always possible, especially if the pregnancy has advanced beyond about four or five weeks. However, it is perfectly possible for a woman with only one functioning fallopian tube to have as many children as she wishes.
A molar pregnancy
A molar pregnancy is a fairly rare condition where the fertilised egg develops, not into a normal foetus, but into something called a hydatidiform mole. This is a bundle of tissue that looks like a bunch of grapes and is similar to some of the tissue found in the placenta (the afterbirth). Molar pregnancies occur only in about one in every thousand pregnancies and can be difficult to detect in the early stages as they give a strongly positive pregnancy test and all the usual symptoms of pregnancy, such as sickness etc. However, as the abnormal pregnancy enlarges it may start to cause abdominal pain and heavy vaginal bleeding. The diagnosis is usually made when an ultrasound scan is done.
The cause of molar pregnancies is not known but they are more common in women who become pregnant either at the beginning or the end of their fertile age (ie very young or older women) or in women who have had a molar pregnancy before. The significance of this condition, apart from the disappointment and distress it causes to a woman who thought she was experiencing a normal pregnancy, is that in some (not all) cases it can lead on to a rare type of cancerous growth called choriocarcinoma.
The treatment of a molar pregnancy is evacuation of the womb (similar to the ERPC described above). However, the pregnancy hormone human chorionic gonadotrophin (HCG) is then measured at regular intervals to make sure it returns to normal following the evacuation. If the level of this hormone does not return to normal it may signify that part of the mole had choriocarcinoma within it, in which case further investigations are done and, if necessary, treatment for this condition is started. Treatment for choriocarcinoma consists of chemotherapy, which in most cases is successful in eradicating the tumour.
How is bleeding in early pregnancy treated?
As you can see from the various possible causes of vaginal bleeding in pregnancy, the treatment will depend on the cause. However, in most cases the doctor will start with a history (a description of the problem given by the patient) and will examine the woman to see if she has signs of vaginal infection, a cervical polyp or cervical erosion. If the doctor feels that these are unlikely to be the cause, he or she may feel an examination is not appropriate. It will depend on the circumstances and the symptoms.
If there is still doubt as to the cause, either an ultrasound examination or (if an ectopic pregnancy is suspected) immediate admission to hospital is organised. Some hospitals now have what are called 'early pregnancy' clinics to cope with the demand for investigation of bleeding in early pregnancy; it is such a common symptom. The treatment and follow-up will then depend on the cause of the bleeding as described above.
It is important, therefore, that any woman who experiences bleeding in early pregnancy should report it to her doctor, especially if it is associated with abdominal pain.
Bleeding in later pregnancy
There are a number of causes of bleeding in pregnancy after 20 weeks' of pregnancy ie past the halfway mark. Bleeding at this stage of the pregnancy should always result in seeking medical advice since it could signify a problem that may threaten the life of the foetus.
Placenta abruptio (Placental abruption)
The placenta (what is often referred to as 'the afterbirth' since it is pushed out by the womb after the baby has been born) is the structure that attaches the unborn baby to the womb and provides the foetus with oxygen and nutrition via the umbilical cord. It is therefore vital to the continuation of the pregnancy since any problem with the placenta is liable to affect the oxygen supply and feeding of the baby inside the womb.
Placental abruption occurs in about 1% of pregnancies and is a situation where the placenta (which looks something like a flat dish which attaches itself to the side of the womb) becomes partially detached from the womb before the baby has been delivered. Placenta abruption causes bleeding and sometimes the formation of a clot of blood between the placenta and the womb wall.
It is not known what causes placental abruption but high blood pressure, cigarette smoking and multiple pregnancies (twins, triplets etc) make it more likely to occur. Having had a placental abruption in a previous pregnancy means that there is a 10% chance of it happening in subsequent pregnancies.
The symptoms of placental abruption include vaginal bleeding in the second half of pregnancy although it occurs more commonly in the third trimester. This bleeding is often accompanied by continuous abdominal pain and tenderness (which is different to the intermittent pain from contractions).
If placental abruption is suspected, a scan will be performed not only to confirm the diagnosis but also to assess the size of the separation of the placenta from the womb.
There is no specific treatment for an abruption so a decision on management is made taking into account the size of the abruption and the maturity of the foetus. For instance, if the abruption is small and the foetus does not appear to be in danger and would be premature if delivered, then the woman is monitored carefully with repeat scans.
On the other hand, if the abruption is large or the pregnancy is nearly full term, a decision will probably be made to deliver the baby, usually by Caesarean section to avoid the risk of the placenta detaching during delivery.
Placenta praevia is a situation that occurs in about 0.5% of pregnancies where the placenta, instead of attaching itself to the side of the womb, lies over part or the whole of the cervix at the bottom of the uterus. This is a problem since the cervix (neck of the womb) is essentially the exit through which the baby is due to be born. In addition, as the womb enlarges and stretches to accommodate the growing foetus, the many blood vessels of the placenta become stretched and may tear, resulting in bleeding.
The amount by which the placenta is covering the cervix is graded into four grades:
- Grade 1 is where the lowest edge of the placenta is attached to what is called the lower segment of the uterus which is the area of the uterus surrounding the cervix.
- Grade 2 is where the lowest edge of the placenta reaches, but does not cover, the internal os (the cervical exit from the womb).
- Grade 3 is where the placenta partially covers the internal os.
- Grade 4 is where the placenta fully covers the internal os therefore completely blocking the exit from the womb.
The significance of these grades is that grades 1 and 2 are considered minor degrees of placenta praevia because they often correct themselves as the pregnancy progresses or may not prevent a normal vaginal delivery. However, grades 3 and 4 correspond to major degrees of placenta praevia because they are unlikely to correct themselves and almost always prevent a normal vaginal delivery from taking place.
If placenta praevia remains undiagnosed until labour starts (unlikely in these days due to the use of ultrasound scans) there may be severe bleeding risking the life of the mother and baby.
The cause of placenta praevia is not known but is more common in women who smoke, are over the age of 35 and in women who have had surgery on their womb such as a previous Caesarean section. It is also more likely to occur in multiple pregnancies such as twins or triplets. Women who have had placenta praevia once have a slightly increased chance of having it occur in a subsequent pregnancy.The most common symptom of placenta praevia is painless vaginal bleeding in the second half of pregnancy. A subsequent ultrasound scan will show the placenta to be attached low down in the womb either fully or partially covering the cervix.
Quite frequently placenta praevia will have been discovered on a routine scan done in early pregnancy before it has caused any symptoms at all. On these occasions, frequent follow-up scans are performed and quite often the placenta will be seen to gradually move away from the cervix as the womb enlarges, particularly in cases of grade 1 or 2 placenta praevia, in which case the problem may correct itself.
If placenta praevia continues to the third trimester of pregnancy or if any bleeding is likely to be putting the health of the mother or baby at risk, the baby is usually delivered by either planned or emergency Caesarean section depending on the circumstances.
Placenta accreta is not generally a cause of bleeding during pregnancy but can result in severe bleeding after delivery. It is caused by the placenta attaching itself too firmly to the side of the uterus and therefore not separating after the baby has been delivered.
Normally, the placenta separates from the side of the womb after delivery of the baby and is, itself, delivered. This allows the uterus to contract on itself and this prevents further bleeding. However, with placenta accreta the placenta fails to separate. The uterus is therefore prevented from fully contracting and so continues to bleed.
For some reason placenta accreta is more common in women who have had placenta praevia or a previous Caesarean section or other surgery on their uterus. However, it is not common-affecting only about 1 in 2,500 deliveries.
The treatment of placenta accreta involves emergency surgical removal of the placenta. In cases where placenta accreta is diagnosed on ultrasound before the baby is born, a planned Caesarean section is performed followed by surgical removal of the placenta or, if this is not possible, a hysterectomy.
Most people are aware that there are different blood groups such as group A, B, AB and O. Each person has one of these blood groups and in addition is either rhesus blood group positive (+ve) or negative (-ve). It is also common knowledge that it is dangerous to receive a blood transfusion of an incompatible group.
A similar situation can occur if a woman who is rhesus negative becomes pregnant with a baby who is rhesus positive because a small amount of the baby's blood can leak across the placenta (afterbirth) into the mother's bloodstream. The same is true if a rhesus negative woman suffers bleeding in pregnancy for any reason, including those described above since, during the bleeding, a small amount of blood may leak into the mother's bloodstream. This can result in the mother producing antibodies called anti-D to a substance called D antigen, which exists in rhesus positive blood. If nothing is done to prevent this antibody production there is a danger that in subsequent pregnancies, the mother's body will react to a future rhesus positive baby, causing a problem called rhesus incompatibility, which can be dangerous for the baby.
This problem can be prevented by giving an injection of anti-D to rhesus-negative mothers after they have given birth, following an actual or threatened miscarriage, especially if it is after the 12th week of pregnancy or following an ectopic pregnancy or any situation where there is bleeding in pregnancy. In fact it has been proposed that in future all rhesus negative women who become pregnant and who do not already have antibodies from a previous pregnancy should be offered anti-D injections during pregnancy in an effort to reduce the numbers of babies affected by rhesus incompatibility.
Last updated 8 August 2021