Miscarriage which is also called spontaneous abortion is defined as the loss of a pregnancy before 20 weeks of gestation.
In the first 1/3 of pregnancy it is called a first trimester miscarriage and in the second 2/3 up to 20 completed weeks it is called second trimester miscarriage.
After 20 completed weeks a baby is considered to be legally (in NSW) viable and so a woman does not miscarry but rather experiences a preterm delivery.
- A threatened miscarriage is where there is bleeding and the baby is still alive in the uterus.
- An incomplete miscarriage is when some of the pregnancy tissue has been passed and some remains in the uterus.
- A complete miscarriage is when all the pregnancy tissue has been passed.
- An inevitable miscarriage is where there has been bleeding and the cervix has opened in preparation for miscarriage.
- A missed abortion is where the baby has died but there is no miscarriage. An ultrasound sometimes shows an empty pregnancy (gestational) sac.
- Recurrent miscarriage or habitual pregnancy loss is defined as three or more consecutive, spontaneous pregnancy losses. When woman has recurrent miscarriages of unknown cause the term idiopathic recurrent miscarriage is used. .
First trimester miscarriage is much more common and the causes of first and second trimester losses often differ.
It is generally considered about 20% of pregnancies end in miscarriage, most often within the first 12 weeks (in the first trimester). The incidence is probably more as there are times a woman has a funny; late period though without a positive pregnancy test it was not confirmed as due to miscarriageThe causes for miscarriage include:
What can be done?
- Genetic/chromosomal defects of the embryo (early foetus): Occasionally but not usually this is due to an inherited genetic trait from mother or father. The incidence increases with maternal age.
- Maternal age: In the mid 30s this starts to become an issue, with the risk of foetal loss increasing with increasing age in late 30?s and more markedly when a woman is in her 40's. There are multiple background factors the can cause this.
- Uterine abnormalities: This includes an abnormal shape of the uterus and fibroids
- Incompetent cervix: An incompetent or weak cervix may cause second trimester miscarriages or premature labour.
- Inadequate ovarian progesterone production: This is when the ovaries do not produce enough progesterone hormone for successful implantation and /or maintenance of the early pregnancy. Progesterone helps to prepare the lining of the uterus for implantation and creates a nutrient rich environment for the developing baby.
- Polycystic Ovarian Syndrome: PCOS can cause difficulty conceiving as well as miscarriage.
- Other hormonal conditions: Poorly controlled diabetes and thyroid disease will increase the incidence of miscarriage.
- Autoimmune disorders : Antibodies are designed to fight off infection in the human body. With certain autoimmune disorders antibodies fight off the developing pregnancy tissues as if it is a foreign body or infection. Antiphospholipid syndrome (APS) is an autoimmune disorder diagnosed by blood tests that detect levels of anticardiolipin antibodies and lupus anticoagulant. Antibodies, such as anticardiolipin antibodies, can cause blood clots that clog up the blood supply to the placenta. Without the placenta supplying nutrients, the pregnancy will perish.
- Blood conditions: Certain inherited conditions mean that your blood may be more likely to clot than is usual. These conditions are known as thrombophilias. If you have a Thrombophilia it can increase your risk of miscarriage.
- Uterine natural killer cells: uNK cells are the most numerous white blood cells found in lining of the uterus that occurs during pregnancy (the decidua). Increased numbers of uNK cells can result in recurrent miscarriages.
- Infection: Infection can cause a miscarriage but is an uncommon cause of recurrent miscarriage.
- Multiple: It is possible to have more than one risk factor for miscarriage
- Unknown causes: Sometimes no cause for miscarriages is found. This does not mean there is no cause but rather medical science today has not discovered all the reasons for miscarriage.
Management varies according to the situation and cause. You should notify your obstetrician if you have bleeding so there can be correct management.
This may include an internal examination and ultrasound scan and often progesterone and HCG blood tests to help clarify the situation.
- If it is threatened miscarriage then rest and sometime progestogen pessary support is indicated. Often the bleeding stops and the pregnancy continues.
- If an early pregnancy inevitable miscarriage or missed abortion then expectant management for a short time will suffice if this is your preference or else a curettage of uterus can be done.
- If after a period with an early pregnancy loss or an advanced pregnancy with inevitable miscarriage, missed abortion or an incomplete miscarriage or if there is heavy bleeding or significant pain then a curettage of uterus is indicated.
- If a complete miscarriage then nothing further needs to be done.
Your blood group will need to be checked and if you are Rhesus negative anti-D immunoglobulin needs to be given within 72 hours of bleeding.
Your next pregnancy planning and management
will depend on what is the most suitable for you with consideration of what is the most likely cause for your miscarriage.
If appropriate I would be pleased to see you. I have a special interest in management of recurrent miscarriage and have been able to help many women have successful pregnancies who had before had miscarriages.
I am able to offer a full range of treatment options including approached not widely available in Australia. http://www.obstetricexcellence.com.au/questions-and-answers/miscarriage
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