Recurrent Pregnancy Loss, or repeated miscarriage's
are common. About one out of every five or six pregnancies ends in miscarriage,
usually in the first few months. The thinking now is that a good portion of
infertility is simply very early miscarriage.
This theory was reported in the American
College of Gynecology (ACOG) September 1995 Bulletin. "Approximately 50-70%
of pregnancies end in spontaneous abortion.
Some women experience repeated miscarriages, which can be caused by subtle genetic
abnormalities in the couple's chromosomes,
problems with the uterine cavity (fibroids, scar tissue, developmental defects),
or other disorders. Problems in the number or structure of the chromosomes or
the genes can lead to miscarriage. Frequently this is nature's way of ending
a pregnancy in which the fetus was not
developing normally. Most chromosomal problems occur by chance and are not likely
to recur in later pregnancies. But in a small number of cases, chromosomal problems
can cause repeated miscarriage. Most of these pregnancy losses are unrecognized
because they occur before, or at the time of, the expected menses".
All women who have three or more miscarriages
should be tested, especially if the miscarriages are consecutive. The cause
of Miscarriage can be identified in most couples and treatment can often resolve
the problem.
Most miscarriages occur within the first
12 weeks of pregnancy (first trimester). If vaginal bleeding occurs after a
viable fetus has been documented, the
chance of miscarriage is increased to about 20 percent. The risk of miscarriage
increases for women 35 years and older. One of the causes of early miscarriage
is an abnormal number of chromosomes.
In order to determine whether there is a genetic cause for miscarriage, a karyotype
on the fetal tissue and/or on blood from both parents may be ordered. If both
parents have a normal karyotype, it is likely that the miscarriage was a chance
event and the couple should feel comfortable continuing to try to conceive.
In cases where a patient is going through
IVF, another procedure called Preimplantation Genetic
Diagnosis (PGD) can be performed on the embryo prior to implanting it back
into the uterus. Although there are only a handful of Fertility programs throughout
the United States currently performing PGD, Coastal Fertility Medical Center
will pioneer the use of PGD in Orange County beginning in the fall of 2000.
Approximately 10 to 15 percent of women
with a history of recurrent pregnancy
loss
have an abnormally shaped uterus. A septate
uterus, which involves tissue protruding into the inner cavity of the uterus,
causes miscarriage due to inadequate blood supply to the fetus.
Another uterine abnormality involves patients whose mothers took Diethylstilbestrol
(DES) while pregnant. Women exposed to DES, who subsequently become pregnant,
have a significantly greater incidence of miscarriage, premature labor, and
infertility.
Uterine fibroids
(common, non-cancerous tumors) can also interfere with the implantation
or growth of a fetus. Fibroids can increase in size during pregnancy and result
in miscarriage. This condition can usually be corrected with surgery.
In some cases, the cervix
begins to open prematurely and is too weak to support a pregnancy. Once an incompetent
cervix has been discovered and corrected, a
subsequent pregnancy can usually be carried to term.
In the luteal
phase (second half of the menstrual cycle), under the influence of the hormone
progesterone, the endometrium
thickens and becomes a healthy environment for a growing embryo.
If progesterone production is low, the endometrium fails, preventing the embryo
from implanting. This is easily corrected by administering progesterone either
by capsules or injection.
Another theory suggests that during a normal
pregnancy, the fetus containing the father's
foreign genes, survives in the mother's uterus
because of a protective response from the mother's immune system. In certain
couples, this protective response does not occur allowing the maternal immune
system to actively attack the fetus, recognizing the father's material as foreign,
resulting in miscarriage.
Smoking, drinking, and illegal drug use
can increase the risk of miscarriage. Women should always consult their physician
before taking any medicine during pregnancy, and also need to alert doctors
and dentists before receiving x-rays or prescriptions for medicine.
The volume of blood flowing to the uterus
effects implantation and development of the
fetus. The position of the uterus
and the diameter of the vessels to the uterus affects blood flow. Another factor
that affects blood flow is the position of the patient. At Coastal Fertility
Medical Center, we use medications, hormones, and activity to influence blood
flow.
Many abnormalities of the uterus, which
are linked to miscarriage, can be treated with surgery. A special X-ray (hysterosalpingogram)
can detect abnormalities of the uterine cavity, and an endometrial
biopsy can provide information about the uterine lining, where implantation
occurs.
In some cases the mother's illness has been
linked to miscarriage. Systemic Lupus Erythematosus
and other autoimmune disorders, congenital
heart disease, severe kidney disease with high blood pressure, uncontrolled
diabetes, thyroid disease or an intrauterine infection interferes with pregnancy.
When these illnesses are treated, the chances for a successful pregnancy improve.
Disorders of the immune system can also
lead to miscarriage. The immune system defends the body against disease by recognizing
and attacking foreign substances. The mother's body normally protects the fetus
from an attack by her own antibodies, but in
some cases this protection may be absent in a woman's blood. Problems in the
immune system can be diagnosed with a blood test.
Hormone imbalance may also lead to recurrent
pregnancy loss . The hormone progesterone prepares
the lining of the uterus for the fertilized
egg during the second half of the menstrual cycle. When an egg is fertilized,
this hormone continues to prepare the uterine lining for the embryo.
Enough progesterone must be made to maintain the pregnancy, otherwise miscarriage
will occur. If tests indicate that a woman's body is not producing enough progesterone,
supplements can be prescribed to correct the problem.
After a miscarriage, it's normal for couples
to questions why, and experience a period of grief. These reactions are normal,
and it is important to understand that each partner may feel and cope differently.
Although it may be difficult, couples should talk about the loss with family
and friends. (see our section on "Coping
with Infertility".)
Some women who have experienced recurrent
miscarriage may feel doubtful that they will ever have a child, but the encouraging
news is that the success rate with treatment is high, especially with certain
uterine and hormonal causes. In cases where no cause is discovered and no treatment
prescribed, the chance of achieving a healthy pregnancy despite having had several
miscarriages is still generally better than 50 percent.