Wednesday, August 29, 2007

A loss that is hard to bear

As soon as a pregnancy is detected, each prospective parent looks forward to and plans for their new arrival. If the pregnancy is lost this is often considered a death within the family. The loss of a pregnancy can be devastating for a couple regardless of the number of children in the family or the cause for the loss. Many couples blame themselves for their pregnancy loss. It is very rare that either member of the couple has done anything that would result in a pregnancy loss.

Recurrent pregnancy loss (RPL) (recurrent abortion; habitual abortion) is typically defined as three or more consecutive pregnancy losses that occur usually before 20 weeks of gestation.

Although approximately 25 per cent of all pregnancies result in miscarriage, less than five per cent will experience two consecutive miscarriages, and only one per cent will experience three or more.


The causes for RPL could be divided into two major categories namely, foetal and maternal.

Foetal causes: These include the genetic composition of the foetus. It is uncommon to find an inherited genetic cause for recurrent miscarriages. A chromosome analysis performed from the parents' blood identifies an inherited genetic cause in less than five per cent of couples.

In contrast to this, many early miscarriages are due to the denovo (by chance) occurrence of a chromosomal abnormality in the embryo. About 60 per cent or more of early miscarriages may be caused by a random chromosomal abnormality, usually a missing or duplicated chromosome.

Maternal causes: These include abnormalities in the environment in which the foetus develops. The chance of miscarriages increases as a woman ages.

After the age of 40 years, more than one-third of all pregnancies end in miscarriage. Most of the embryos have an abnormal number of chromosomes.

Distortion of the uterine cavity is considered to cause about 10 to 15 per cent of recurrent miscarriages. The most common abnormality is a uterine septum i.e., a partition of the uterine cavity. The diagnosis can be made by x-rays or ultrasound scan of the uterus.

The other congenital abnormalities include a double uterus, and a uterus in which only one side has formed. Scar tissue in the uterine cavity, large uterine fibroids and polyps could result in pregnancy loss. In the second trimester, a weak cervix can become a recurrent problem. Most of these conditions can be surgically treated.

Immunological Causes: Two major categories of immunologic causes of RPL are autoimmune, in which the woman's immune system attacks her own organs and tissues, and alloimmune, in which the immune system attacks tissues considered foreign.

Autoimmune disease or dysfunction may play a role in up to 10 per cent of RPL. Phospholipids are molecular building blocks that form a large portion of the walls of cells in the body, which includes placental cells.

Antiphospholipid syndrome (APS) is an autoimmune dysfunction where antibodies are produced against phospholipids that form part of the blood vessel walls.

Hence clots are produced in the placental blood vessels blocking off the blood supply to the foetus thus producing foetal demise.

Without treatment, couples with APS have a poor chance of carrying a foetus to term. Low dose aspirin and low molecular weight heparins definitely help in this sub-group of patients.

Allo immune dysfunction

Normally a person will reject dissimilar (non-self) tissues or structures from the body using the immune system.

In pregnancy, the placenta and growing embryo are not entirely self, but rather are a result of both the maternal and paternal genetic heritages. The placenta has a privileged relationship with the pregnant woman that allows for it to escape rejection. When this mechanism is disturbed, it can result in foetal loss.

Miscellaneous : Causes related to an action of the mother are very uncommon but can include exposure to chemical toxins, X-rays in early pregnancy and rarely heavy smoking and alcohol abuse. Medications taken during pregnancy should be reviewed with an obstetrician.

Treatment: The two main treatment options are as follows: Leucocyte immunisation with paternal or donor blood cells, or immunoglobulin treatment with IV injections, which is very expensive. This should be conducted only in research settings, as their benefits are largely unproven.

Poorly controlled diabetes increases the rate of miscarriage.

Women with diabetes improve pregnancy outcome if blood sugars are controlled before conception. Women who have insulin resistance, such as obese women and women with polycystic ovaries also have higher rates of miscarriages.

The second half of the menstrual cycle, that is the time from ovulation up to the next period, is called the luteal phase. This phase is characterised by high circulating levels of a hormone called progesterone in the blood.

Progesterone, which is produced by the ovary after release of an egg (ovulation), is necessary for a healthy pregnancy.

Inadequate levels of progesterone, often called as luteal phase deficiency may cause repeated miscarriages. This concept is still under controversy and needs more evidence to prove the absolute necessity of progesterone for the development of a strong pregnancy. If an inadequate progesterone effect is documented or believed to exist during the luteal phase of the menstrual cycle, then either supplemental progesterone (either as oral tabs, vaginal pessaries, vaginal gel or injections), or supplemental HCG (human chorionic gonadotrophins) as injections every few days following ovulation to enhance the ovary's own progesterone productions are treatment options.


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