Introduction
Numerous studies have repeatedly shown that women athletes who
have a low body mass index, ('BMI'), have a difficult time starting
a family. We have found with our patient population that a number of female athletes
have a low BMI. This low BMI often translates into fertility problems. In fact
studies have shown that approximately12% of infertility cases are due to being
underweight or having a low BMI.
Body fat plays a significant role in reproduction. Sex hormones are fat soluble
and they are stored in the body's fat layers. Women that have a low BMI
produce a reduced amount of estrogen which can lead to an abnormal menstrual
cycle. Amenorrhea, or the lack of a menstrual cycle, is a result of a low BMI.
What is too thin and how does this affect fertility?
The ideal body weight from a medical perspective is not an exact science.
Most of the literature suggests that if a woman's BMI is less than 85%
of her 'normal' BMI than she is too thin. A reduced BMI may translate
into difficulties conceiving.
One can determine their BMI by following this equation: multiply your weight
(in pounds) by 705, divide the result by your height in inches, and divide that
result by your height again. A normal BMI is between 19 and 25; you are considered
underweight if you fall below 19, and overweight if you fall above 25.
The problem of having a low BMI does not affect every woman. A low BMI becomes
a problem only when it starts to affect the menstrual cycle and specifically
ovulation. It is possible to menstruate without ovulation. A woman should contact
her physician if she encounters fertility problems without a change in her menstrual
cycle.
As previously discussed the ideal level of BMI is not an exact science. Some
women are naturally thin. If the correct diet pattern, exercise program and healthy
lifestyle are followed there is usually nothing to worry about. If a woman is
thin because of excessive exercise and poor dietary habits, her fertility and
pregnancy success can be adversely affected.
What is considered excessive exercise?
Women come in all shapes and sizes and the amount of exercise that is appropriate
for each woman varies. Some women may exercise in excess of three hours per day,
seven days a week and will have no adverse affects from a fertility standpoint.
Others may exercise only an hour a day, three days a week and have adverse consequences,
again, from a fertility standpoint. When one is exercising the body produces
endorphins. These hormones produce feelings of euphoria which is also known as
the 'runner's high'. Endorphins also increase levels of
prolactin, which the body releases for the production of breast milk. An increase
in prolactin may decrease the possibility of pregnancy.
There are some classic symptoms that every female athlete should look for
and try to correct with regards to their training regiment and fertility.
1) Physical Symptoms
Menstrual irregularities, unexplained loss of weight, elevated blood pressure,
slower heart rate recovery, excessive muscle fatigue, decreased immunity, gastrointestinal
disturbances, and loss of appetite
2) Psychological Symptoms
Depression, decreased self-confidence, mood changes, lethargy, lack of concentration,
anxiety, sleep disturbance, restlessness, and aggression
In addition, female athletes who engage in excessive exercise and have poor
dietary habits are at risk of developing a low BMI which may result in lower
estrogen levels. It is very important for female athletes to maintain the correct
amount of caloric intake while exercising in order to avoid lower estrogen levels.
Should a female athlete experience any of the above symptoms she should contact
her physician.
Conclusion
Exercise and athletic competition is more than recreation for many women.
Yet excessive training, poor diet and a low BMI can affect fertility. We believe
that a smart training program for the female athlete consists of a realistic
exercise program combined with sufficient sleep, a healthy diet and adequate
caloric intake resulting in a healthy BMI. A healthy life structure provides
the female athlete with the ability to not only compete effectively but also
maintain her options with regards to fertility and her ability to have a family.
© Copyright Wendy Chang,
M.D.
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