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The hormone that stimulates
production of eggs (oocytes) in the ovary
is secreted from a small part of the brain
(called pituitary gland) is Follicle Stimulating
Hormone (FSH). It is FSH that is administered
on a daily basis by using an injection into
the fatty tissue in the abdominal wall when
OI is used. The response to the hormone
is the development of follicle or follicles
in the ovary that contain the developing
eggs. The progress of the developing follicles
is monitored by measuring the oestrogen
hormone they produce by blood tests, and
by watching them grow on ultrasound examination.
The dose of the FSH is then adjusted with
a small increase every seven to ten days,
in line with the response.
The aim is to stimulate
preferably one or two and a maximum of three
ripe follicles. When the size of the follicle
and the oestrogen level suggests that the
follicle is ripe, another hormone, Human
Chorionic Gonadotrophin (HCG) is administered
which releases the egg. All the couple have
to do usually is to have intercourse around
the time of ovulation.
We usually obtain about
20% pregnancy rate per cycle, with a small
risk of multiple pregnancy (usually only
twins) of about 20%.
The risks are that too
many follicles may be produced, and then
the cycle is cancelled (the HCG hormone
is not administered) and intercourse is
avoided. It is very rare for the symptoms
of sore swollen ovaries with abdominal fluid
(ascites) to develop after OI.
After the first cycle if
there was ovulation but no conception, the
cycle is repeated. If too many follicles
were produced, the dose of FSH is kept lower
for longer.
Over 80% of women who undergo
OI have a successful pregnancy within six
cycles. Occasionally there are other fertility
abnormalities that require progressing to
IVF.
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