Most people think of the thyroid as the butterfly shaped gland that is responsible for the
inner workings of our metabolism. It truly does a lot for us, as one of its main roles is to
produce the hormones that are vital to the functioning of our major organ systems. Seeing
that nearly every cell in our body depends upon thyroid hormones to function, without them
we simply would not survive.
Having a dysfunctional thyroid gland can affect the body in a number of ways, some of
which are more noticeable than others. One area that is often overlooked yet is of great
importance is within the realm of fertility and reproduction. Many couples are surprised to
learn that optimal thyroid function is necessary to conceive and maintain a pregnancy. Even
the slightest imbalance can contribute to difficulty conceiving in both men and women, as
the thyroid interacts closely with our sex hormones and plays a key role in the maturation of
our reproductive cells.
In women both low (hypothyroidism) and high (hyperthyroidism) thyroid function can cause
irregular menstrual cycles and may even cease menstruation altogether. They are a
common cause of anovulation, which happens when an egg fails to develop properly and
does not get released from the ovary at the time of ovulation. When there isn’t an egg to be
fertilized, conception is impossible. It is important to note that if a woman is anovulatory it is
still possible for her to experience a bleed each month. In the case of hypothyroidism the
flow may actually be heavy. If no investigations are performed she may think that she is
cycling properly and may never realize that her fertility is impacted.
Suboptimal thyroid function is also associated with recurrent miscarriage, most commonly in
the initial weeks of pregnancy or before a period is even missed. This happens for a few
reasons, the first being that an underactive thyroid can cause the second half of the
menstrual cycle – the luteal phase – to shorten. When this occurs, the uterine lining is not
strong enough for an embryo to implant and sustain a pregnancy – even if fertilization had
taken place. In most cases the pregnancy is lost before the woman even realizes that she is
pregnant. The second reason specifically has to do with an autoimmune subtype of thyroid
disease wherein the body inappropriately attacks the thyroid gland. This type of condition
results in the production of antibodies that can affect a woman’s ability to sustain a
pregnancy shortly after conception takes place. Since many patients with autoimmune
thyroid problems can present asymptomatically, it often goes undiagnosed until several
miscarriages have occurred or testing is acquired.
Since our thyroid hormones are so tightly linked with our reproductive hormones, an
imbalance in one may cause an imbalance in the other and vice versa. For example, if
estrogen is high in relation to progesterone the liver will produce more of a protein called
thyroid binding globulin, which essentially acts to do just that – bind up the thyroid hormone
and make it unusable by the cells. This is the reason why low thyroid function is often
associated with other reproductive health concerns such as polycystic ovarian syndrome
(PCOS) and endometriosis. As such, thyroid imbalances should not be addressed in
isolation but instead looked at as a whole with the other reproductive hormones.
If you have been trying to have a baby for some time, have irregular periods, or have been
diagnosed with unexplained infertility it might be worth looking into the function of your
thyroid gland. Many thyroid problems unfortunately go undiagnosed because a full thyroid
evaluation is not usually offered as part of routine care. In most cases only the TSH level is
measured, which is a hormone sent out by the brain whose job is to instruct the thyroid
gland to produce more or less thyroid hormone depending on the needs at the time. The
result of this test is merely for screening purposes and only provides a brief snapshot of the
overall thyroid function because it does not look at the level of the available thyroid
hormones themselves. Research suggests that the TSH level should be between 1-2 mIU/L
for optimal fertility. However, for completeness, the actual thyroid hormones (free T3 and
free T4) and thyroid antibodies (anti TPO and anti TG antibodies) should also be included.
Thyroid conditions can present in a number of different ways, depending on the severity and
what other hormones may be involved. In many cases the symptoms are vague or are not
present at all, which can make it even more difficult to identify.
Common symptoms of an under-active thyroid may include:
Heavy and irregular periods
- Brain Fog
Common symptoms of an over-active thyroid may include:
Light and irregular periods
If you suspect that your thyroid may be contributing to your fertility troubles and want to
have it properly assessed, schedule an appointment with Dr. Jessica Geil at 905-892-1318
or by clicking HERE.
Dr. Jessica Geil, ND
Health Over All
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