What
are the causes of recurrent miscarriage?
Here
are some of the most common causes of recurrent miscarriage:
Genetic/Chromosomal
Defects: Up to seventy percent of miscarriages are
caused by chromosomal errors. Chromosomal abnormalities are
more common in women who are over thirty-five. In most cases
chromosomal defects are a random occurrence and are not likely
to reoccur in subsequent pregnancies. Although chromosomal
errors are the cause of the majority of miscarriages, they
are not usually caused by an inherited trait from mother or
father. Less than five percent of couples tested will have
an inherited genetic cause of such chromosomal defects.
Age:
After thirty-five the risk of miscarriage increases. After
age forty, more than 33 percent of pregnancies will result
in miscarriage. However, keep in mind the rate of miscarriage
prior to age thirty-five is about ten to twenty percent.
Uterine
abnormalities: Uterus abnormalities account for ten
to fifteen percent of repeated miscarriages. Some women are
born with a double uterus or an abnormally shaped uterus.
Other problems are scar tissue on the uterus. Uterus abnormalities
may cause problems with proper implantation, create problems
with blood supply to the uterus, or there may not be room
for the baby to develop and grow.
Incompetent
Cervix: Incompetent cervix may cause second trimester
miscarriages or premature labor. Incompetent (or weakened)
cervix may require a surgical procedure called cerclage. Cerclage
is a surgical stitch around the cervix to help keep it from
dilating prematurely.
Hormonal
causes:
- Luteal
phase defect – Luteal
phase defect occurs when there is not enough
progesterone produced during the luteal phase of the menstrual
cycle. Progesterone
helps to prepare the lining of the uterus for implantation
and creates a nutrient rich environment for the developing
baby. Some researchers believe that Luteal Phase Defect
is responsible for up to forty percent of recurrent miscarriage;
however, there are some questions as to the accuracy of
these studies. Treatment for Luteal Phase defect includes
taking progesterone supplements or suppositories with future
pregnancies. There is some controversy over prescribing
progesterone for miscarriage treatment. There have not been
enough controlled studies to confirm its effectiveness or
to ensure its safe usage during pregnancy.
- Polycystic
Ovarian Syndrome – PCOS
has been linked to miscarriage. Women with PCOS have higher
levels of male hormones. This has been associated with infertility
as well as miscarriage. Over a third of all women who have
recurrent miscarriage also have PCOS. Treatment of PCOS
often involves insulin-sensitizing medications. There is
not enough evidence to show that this is an effective treatment
for miscarriage; nor is there enough information on its
safety during pregnancy.
- Other
hormonal conditions: Poorly controlled Type
1 Diabetes has been associated with miscarriage. Improving
blood sugars before conception will improve the outcome
during pregnancy.
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. Treatment for antiphospholipid
syndrome includes low dose aspirin or heparin. The research
is still out on these treatments effectiveness in preventing
miscarriage.
Infection:
Certain infections have been linked to miscarriage. Genital
infections such as bacterial vaginosis may increase a woman’s
risk of having a miscarriage. Testing for infections is not
routinely done in women who have no symptom of infection.
Male
factor: There is some evidence that defects in the
male’s sperm may
cause miscarriage. It is not known how often sperm defects
are the cause of recurrent miscarriage.
Unknown
Causes: Many couples do not find the cause of their
recurrent miscarriages. Fifty percent or more do not find
a cause even after testing. Furthermore, it is possible to
have different causes for each miscarriage. With this consideration
it may not be possible to discover a pattern for a woman's
miscarriages. The good news is that even if a woman has had
multiple miscarriages the odds of having a successful pregnancy
are still in her favor. In sixty to seventy percent of couples
with unexplained pregnancy loss, the couple will go on to
have a successful pregnancy.
Sources:
American
College of Gynecology
American
College of Obstetricians and Gynecologists
March
of Dimes
American
Society for Reproductive Medicine
