While there are many recurrent miscarriage causes, the most common is a genetic error during the first few days after conception
When you conceive and a baby is created, it takes half its genes from the sperm and half from the egg that ovulated that month. At the exact time of conception, the cross-over of these genes takes place. Sometimes, for no reason other than bad luck, some gene information is lost and the pregnancy is destined from that point not to be. It might be that this lost information is not needed for many weeks, and the pregnancy will continue as normal until that time. When the needed information is not there, it is then that you begin to miscarry.
Sometimes when this happens, the miscarriage doesn’t happen right away. This is called a ‘missed’ miscarriage and may not be picked up until some weeks later, following a slight blood loss or period-type pains. Another cause might be that the embryo did not implant, or bury itself, into the womb lining properly – once again, just due to bad luck.
Women who experience miscarriage want to know why did it happen and was it their fault.
Remembering that most often no cause is found, below are some of the things which are thought to be associated with recurrent miscarriage:
Chromosome problems (of the fetus) – Occurs when the fetus has too many or too few chromosomes (such as Down’s Syndrome, or Turner’s Syndrome). Mom and dad are genetically fine, but when put together an unusual gene mismatch occurs. This usually does not re-occur. These pregnancy losses can occur very early or sometimes late in the first trimester.
Chromosome problems (of the Mom or Dad) – Although very rare, the mom or dad may have a minor chromosome problem that only is important in reproduction. Testing of parental chromosomes is recommended if all other tests are normal. Unfortunately, if there is an abnormality, nothing can be done to change it; fortunately, it is unlikely to cause a miscarriage with each pregnancy, so it may just take several attempts before a healthy fetus results.
Antiphospholipid antibody syndrome – this is an immune disease where the main problems are RM, clots in the veins or arteries and often a low count of one of the blood components, the platelets. If pregnancy is successful, it can be complicated by poor growth of the baby and a disease of pregnancy called preeclampsia (high blood pressure and excess protein in the urine).
Uterine (womb) abnormality – Examples include a double-womb or a septum (wall) down the middle. Many times removal of a septum is all that is needed to improve the outcome of the next pregnancy. This is tested with either a special ultrasound (sonohysterogram) or an HSG (Hysterosalpingogram).
Fibroids – benign tumors of normal uterus tissue growing in the muscle, sometimes causing misshaping of the womb cavity. This can interfere with implantation of the embryo or limit the amount of room the baby has to grow.
Cervical incompetence (weakness) – may cause miscarriage in 2nd trimester. Some women are just born with a weak cervix. This is not as common as some people report, and the diagnosis is very difficult to make.
Polycystic ovary syndrome (PCOS) – often this disease causes infertility or trouble even getting pregnant. It has also been found when this is present with a raised hormone level (LH) there is an increased risk of miscarriage. These patients may have an elevated insulin level which can affect the hormone environment important for the developing fetus. It is often treated with medications that improve ovulation or lower insulin.
Immune problems – couples with RM may have some similar components of the immune system. This can make it difficult for mom to make the appropriate response to pregnancy. This is a controversial finding, but can be checked if everything else is normal.
Hormone ‘deficiency’ – in pregnancies which end in miscarriage, sometimes the levels of a hormone called progesterone are found to be low. This is thought to reflect an early pregnancy failure, and is probably the RESULT rather than the cause of the miscarriage. Although progesterone has never been proven to be helpful in preventing pregnancy loss, it is frequently given as it may help a small subset of patients and doesn’t hurt, except to make the patient feel more fatigued.