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Weight
Matters
Maintaining body weight
within a healthy range is an important part of good reproductive health.
This term, healthy weight, refers to two aspects of weight: pre-pregnancy
weight range and appropriate weight
gain during pregnancy. Extremes
of weight on either side, either very thin or obese, increase a woman's
risk of pregnancy difficulty.
Reproductive
hormones are critical to pregnancy success. Because these hormones
are dependant on fat for their normal production and metabolism,
body composition and fat stores directly effect their activity.
Both very low and very high body fat stores, reflected in weight,
can change the body's reproductive abilities. In addition, some
chronic diseases are more likely to accompany higher or extremely
low weights. Any pre-existing disease will add stress to pregnancy
and may effect one's reproductive ability.
Assessing
Weight
One effective
tool used to assess pre-pregnant body weight is the Body
Mass Index (BMI). BMI is used by health professionals to screen
adults for their health risks related to weight. It is based upon
a relationship between weight and height, excluding frame size and
muscle mass. The 'ideal' BMI range, or that which carries the lowest
health risk, is considered 19 to 25. For pregnancy, however, the
recommended pre-pregnancy BMI range is 20-25. Note: the BMI can
not accurately assess health risk based on a woman's weight during
pregnancy or lactation. It also needs to be interpreted differently
for those with high lean body weight (body builders, athletes).
However, when used to assess pre-pregnancy weight status, BMI can
help identify those with higher risks and suggest remedies.
Low
Weight
A
low pre-pregnant weight is defined as a BMI of less than 20. It
can also be determined for a teenager who's body weight is 85 percent
or lower of normal weight for age and height. Concerns for women,
or teens, with excessively low weight include a possible decrease
in their production of estrogen. Inadequate estrogen production
will reduce a woman's fertility and can result in amenorrhea, or
loss of the menstrual cycle, reduced calcium absorption and altered
bone metabolism. Studies have also shown that very low body weight
at the start of pregnancy increases a woman's risk of delivering
a premature or low birth weight baby. For those with a low starting
weight, weight gain before pregnancy and/or a higher weight gain
during pregnancy can help reduce these risks.
High
Weight
Interpretation
of a high pre-pregnant body weight falls into 2 categories. A BMI
between 26 and 29 is interpreted as carrying a slightly higher risk
for health and pregnancy problems. Weight gain recommendations are
lower for women in this BMI range. A BMI of 30 or higher is interpreted
as carrying greater risk. Another interpretation for teens is a
weight which is 30% or more higher than normal for age and height.
In general,
a high BMI suggests increased risk for pre-existing chronic diseases,
such as type 2 diabetes mellitus and hypertension, that will impact
pregnancy. A closely related metabolic alteration is insulin resistance,
which has been linked to fertility difficulties (polycystic
ovary disease) and higher incidences of gestational
diabetes. Further, obesity increases a woman's risks that cesarean
delivery will be required.
For women who
have a high pre-pregnant weight, weight loss is recommended but
should be planned carefully and discussed with a physician. Improper
dieting or rapid weight loss can interfere with the menstrual cycle
and reduce fertility. If pregnancy does occur while a woman is following
a severely restrictive diet, the early weeks of pregnancy may be
effected. A general multivitamin-mineral supplement is recommended
during pre-pregnancy weight loss to ensure nutrient stores remain
high and to protect a developing embryo should pregnancy occur.
Weight Loss And Pregnancy
Intentional
weight loss is NEVER advised during pregnancy. Cease a weight loss effort
once pregnancy is established. Pregnancy hormones change the mother's
metabolism and, as a result, production of ketones occurs more quickly
in pregnant women than others when calories are restricted. Ketones are
toxic to the fetus.
For women who begin pregnancy at a high weight, weight gain goals or pregnancy
are set lower. None-the-less, weight gain is always the objective. If
a slower rate of weight gain is advised and cutting
back calories is suggested during pregnancy, this should be done moderately
and under the supervision of your physician.
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