We traditionally divide pregnancy into three stages or trimesters, each about 13 weeks long. In the first trimester the embryo grows into a fetus, and the placenta (afterbirth) establishes itself in the uterus (womb). By the end of the first trimester the fetus is formed and the placenta is supplying the pregnancy from the mother’s circulation.
In order to make each of us unique, nature takes risks when creating a new life. If the pregnancy or body realise that the pregnancy is unlikely to result in a healthy baby, the pregnancy is stopped and the woman miscarries. Fortunately, not all bleeding in early pregnancy is a miscarriage; in fact only about a third of women who present with bleeding will have a miscarriage.
Bleeding in early pregnancy
Naturally, when a woman develops bleeding in early pregnancy, it causes concern. Not only is there the possibility of a miscarriage, there is also the small chance that the pregnancy may not be in the womb (an ectopic pregnancy). So the first trimester is a critical period in determining the outcome of a pregnancy, with miscarriage the single most common complication of pregnancy.
A dedicated early pregnancy unit, set up to deal with complications that present with symptoms of vaginal bleeding and abdominal pain, is invaluable in modern day practice. Following carefully established guidelines, and with dedicated medical and nursing staff, women can be investigated, using examination, biochemical testing and transvaginal ultrasound. Women with non-viable pregnancies may be cared for in a supportive environment, with the help of trained counselling staff, while those with progressing pregnancies may be reassured and special needs such as administering anti-D immunoglobulin attended to.
Even though about one in four pregnancy ends in miscarriage, it is usually difficult to determine the cause. Many women are left asking the question why? and find it hard to accept that no-one can give a definite answer. It is very unlikely to have been caused by anything you did – miscarriage is very rarely anyone’s fault. If you have bleeding in early pregnancy you should attend an early pregnancy assessment unit.
The main causes of miscarriage are thought to be: Genetic problems, Hormones, Immune system, Infections, Womb problems.
- Genetic problems: About half of all early miscarriages occur because of chromosome abnormalities. These are not usually as a result of anything being wrong with the parent’schromosomes.
- Hormones: Women with hormonal problems find it harder to get pregnant and when they do, are more likely to miscarry.
- Immune system: Problems with the mother accepting the pregnancy can lead to miscarriage.
- Infections: Minor infections like colds are not harmful, but a very high temperature and some specific illnesses of infections, such as German measles, may cause miscarriage. Some researchers have found that high levels of the bacteria in the vagina (bacterial vaginosis) can also increase the risk of miscarriage.
- Womb problems: If the cervix (neck of the womb) is weak, it may start to open as the uterus (womb) becomes heavier in later pregnancy and this may lead to miscarriage. Large fibroids may cause miscarriage in later pregnancy. An irregular-shaped uterus can mean that there is not enough room for the baby to grow in later pregnancy.
Some pregnancies are lost through ectopic pregnancy. This is when the fertilised egg implants outside the cavity of the womb, most commonly in one of the Fallopian tubes.
When a woman suffers three consecutive miscarriages she is diagnosed as suffering from recurrent miscarriage, although if there are two miscarriages after a long time trying for a baby, or if the hopeful mother to be is over 35 years, investigations are often recommended before suffering three miscarriages.
The good news is that the vast majority of women who have three miscarriages will go to have a successful pregnancy and delivery of a healthy baby, but it is wise at this stage to initiate investigations to see if there is an underlying problem with carrying a pregnancy.
Investigations focus on three key areas of concern:
– Antibody or rejection problems
– Mother or father chromosome problems
– Maternal hormone or uterine problems
Antibody and Rejection problems
We know that our body makes antibodies to attack foreign bacteria and viruses that can infect us. The immune system is not perfect so it is also capable of creating antibodies that can attack ourselves (known as auto antibodies). Our immune system evolved from the same system that helps us clot our blood; so some of the antibody problems women suffer from are in fact part of the coagulation or clotting process in our bodies. These problems do not often cause other problems in the early years so the first time a woman finds out about these problems is when she suffers from recurrent miscarriage.
Common antibody problems include Antiphospholipid antibody and Factor V Leiden Deficiency. There is also a lot of work, which demonstrates that you are capable of having too many ‘Natural Killer’ white cells in your womb, which can also lead to miscarriage. The good news is that we can investigate you and identify if you suffer from these problems. A combination of aspirin, anticoagulant or steroids can help block these antibodies and make your body more receptive to remaining pregnant.
About 2% of the population have chromosomes that are perfectly normal for them, but can lead to problems when trying for a baby. The most common problem is called ‘balanced translocation’ this is where a part of one chromosome splits off and attaches to another chromosome, while another piece of chromosome fills the space, which makes your chromosomes ‘balanced’. However when you produce eggs there is a much greater chance there will be a mix up and the baby will not receive a proper set of chromosomes, leading to miscarriage. A simple blood test can find out if you or your partner has any chromosome issues.
Maternal Hormone or uterine problems
The shape of a woman’s uterus or womb may make it more difficult to carry a pregnancy, but the most common problem is fibroids or myoma that interfere with the inner lining of the womb, or are large and interfere with the growth of the womb. An ultrasound scan can find out if there are any anatomical problems in the pelvis.
There are a number of hormone or endocrine problems that can affect a woman’s chances of becoming pregnant and carrying a pregnancy. For instance Polycystic ovarian syndrome [link] can interfere with ovulation and increase the chances of a woman miscarrying. A couple of blood tests can usually identify if there are any endocrine causes for recurrent miscarriage. With the right treatment nearly all the hormone problems can be rectified and a successful pregnancy follows.