are normally born with two ovaries, which contain a
lifetime supply of eggs. Once menses begins at puberty,
eggs develop within the ovarian follicles on the ovary
and are ovulated during each monthly menstrual cycle.
menstrual cycle is controlled by the interaction of
several hormones in the biologic system known as the
"hypothalamic-pituitary-adrenal axis". The
hypothalamus is located at the base of the brain and
is responsible for monitoring and adjusting hormone
levels by sending feedback to the pituitary gland. The
pituitary produces many hormones including follicle
stimulating hormone which stimulates egg development.
the first days of the ovulatory cycle, the hypothalamus
produces gonadotropin releasing hormone (GnRH). GnRH
travels to the pituitary where it stimulates the production
of follicle stimulating hormone (FSH). FSH stimulates
the ovaries to "recruit" eggs and then supports
the eggs within the follicles mature, they begin to
produce increasing amounts of another hormone, estrogen.
Estrogen levels rise signaling the hypothalamus to reduce
production of FSH as the eggs approach maturity. Estrogen
also stimulates the development of the endometrium (lining
of the uterus) which must become thick and vascular
to support the developing embryo.
the eggs mature, the hypothalamus signals the pituitary
to produce a large surge of leutinizing hormone (LH).
LH triggers ovulation, or the release of the egg from
the ovarian follicle. The egg travels through the fallopian
tube to the point of fertilization at the distal end.
ovulation, the residual follicle develops into a structure
known as the corpus luteum and begins production of
progesterone. Progesterone also stimulates and supports
the development of the uterine lining. Once pregnancy
occurs, the placenta begins to produce progesterone
to support the endometrium during an ongoing pregnancy.
is the lack of ovulation and oligoovulation is irregular
ovulation. Ovulatory irregularities are a common cause
of infertility and can be caused by hormone abnormalities,
which can result from diseases such as PCOS. Abnormal
ovulation can also be caused by too much exercise and
have a fertilization capability that is related to age
and individual genetic factors. As the eggs age, the
level of FSH rises and is measured on day 3 of the menstrual
cycle. Levels above 12 mcg/ml are indicative of the
onset of menopause or perimenopause. The clomiphene
citrate challenge test is also used to measure "ovarian
reserve", or the eggs fertilization and development
capability. Many fertility clinics will not perform
IVF with women who fail the clomiphene citrate challenge
test because success rates are very poor.
irregularities are often treated with Clomid (clomiphene
citrate). Clomid works at the hypothalamus by competing
with estrogen. Lower levels of estrogen signals the
hypothalamus to increase production of GnRH with increases
production of FSH.
pregnancy has not occurred after 3-6 cycles of Clomid,
injectable FSH is usually the next step. FSH stimulates
the ovaries directly causing the production of many
eggs. Numerous eggs are necessary for ART procedures
such as IVF.
should be administered by a specialist thoroughly trained
in its use. Dosages must be monitored and adjusted to
prevent side effects, such as hyperstimulation syndrome
and multiple births.
the eggs will not fertilize due to poor ovarian reserve
or other factors, donor egg is usually the best option.
Donor egg recipients have the same IVF success rates
at the age group of the donor. For example, if a 22
year old woman's eggs are used and the success rate
for this group is excellent, the recipient will have
a 40% to 70% chance of pregnancy. This percentage varies
according to the clinical practice rates as well as
the couple's specific medical history.
women under 35, most ovulatory disorders can be effectively
treated with medications and/or lifestyle changes. (Read
More- Age and Infertility)