Nutrition During Pregnancy Part I: Weight Gain, Part II: Nutrient Supplements (1990) / Chapter Skim
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4 Assessment of Gestational Weight Gain
4 Assessment of Gestational Weight Gain
Pages 63-95
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From page 63... ...
Therefore, major emphasis should be placed on establishing and implementing data collection techniques that provide the most reliable and accurate data possible for the particular clinical setting. Clinical data relevant to gestational weight gain include weight, height, and gestational age.
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From page 64... ...
per month, with this degree of error, it might be very difficult to distinguish abnormal weight gains from measurement error over relatively short intervals. Subjects should be weighed on a platform beam balance scale with movable weights or on a high-quality electronic scale.
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From page 65... ...
Gestational Duration The adequacy of accumulated weight gain or achieved weight status at any given stage of pregnancy can be determined only when the length of gestation is known. An accurate estimate of length of gestation is also essential for research on gestational weight gain and fetal growth.
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From page 66... ...
A shift of several weeks in the gestational age estimate does not affect the interpretation of the rate of gain, since it is generally linear over a broad range of pregnancy from 13 to 35 whelp of gestation. Assessing Prepregnancy Weight for Height ~ assess prepregnancy weight for height, it is necessary either to calculate BMI or to compare the weight for height to a weight-for-height reference standard (e.g., MLI ideal weight tables)
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From page 67... ...
There is no statistical or scientific basis for prescribing one set of cutoff values or reference standards over another when assessing prepregnancy weight. The relationship between prepregnancy weight and various fetal or maternal outcomes is generally considered to be linear, with no welldefined threshold at either end of the prepregnancy weight distribution, but this view has not been verified by research.
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From page 68... ...
Weight Gain Charts Many different weight gain charts and tables are available for use in the clinical assessment of gestational weight gain; Table 4-1 presents selected examples representing a wide range of applications. An evaluation of the characteristics of these various charts is useful in considering their application in the clinical setting.
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From page 69... ...
elaboration of the charts that incorporate prepregnancy weight status by inclusion of more recent normative data on gestational weight gain, and (4) elaboration of prepregnancy weight classification to establish target weights based on some percentage of the ideal or reference prepregnancy weight.
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70 v, o cq 'e ct a)
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72 ._ 4 o l Cal o ._ 2 Ct o ·-C5 Ct V, O ~ .= ~C: o ._ o us .o o U' so ~ Ct Cal U
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From page 73... ...
In order to accommodate inconsistency in the application of proportionate weight gain recommendations across the range of prepregnancy weight for height, Rosso (1985) developed a weight gain grid that applies different assumptions of weight gain patterns for underweight and overweight women (Figure 4-8~.
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From page 74... ...
. Lower and upper lines represent extremes of achieved weight gain.
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From page 75... ...
Wl. Weigl~t 10S~J37 138 107-141 142 109-143 144 1 1 1-14S 146 1 14-149 lS0 1 IC-1S3 IS4 1 19-lS6 IS7 122-lC0 161 124-163 164 127-167 168 130-171 172 1 32-1 74 1 7S 13S-178 179 141-185 186 143-1 89 1 90 146-192 1 93 28 26 ~d 20 18 16 14 12 10 t0 75 8 10 12 14 16 18 20 22 24 26 28 30 32 34 38 38 40 42 sn 48 4~; 44 d, 40 38 32 30 28 ,£ 24 ,, 20 18 1R lt 1, n 8 6 4 2 2 4 1n 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 | WEEKS GESTATION | FIGURE 4-3 Weight gain grid from Georgia WIC (Georgia Dietetic Association, 1987~ Lower dashed line is recommended gain for overweight women; upper dashed line is recommended gain for underweight women.
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From page 76... ...
76 e ~ 11 U] ~ 0 Y '~nunol _ _ C o' 43 0 a' 3 Be: ._ C)
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From page 78... ...
is standard weight or actual prepregnancy weight, whichever is greater. Women who are at standard weight at conception and obese women have their prepregnancy weight plotted at zero.
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From page 79... ...
2 ~ -44 _42 _40 38 38 34 -32 3 30 28 2 _ 26 -24 0 -22 -20 _ 18 _16 _14 _ 12 10 8 6 - 2 - O -2 -3 - -3 -4 - 4 8 6 3 2 o 1 2 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 421bs. Kg 20 Prenatal Weight Gal n Grids Pre-pregnancy Weight Status Underweight ~ ~ )
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From page 80... ...
heavier than the 1983 MLI values (Metropolitan Life Insurance Company, 1983) used, for example, with the chart depicted in Figure 13.
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From page 81... ...
There is no evidence that the desirable weights for height in either of the MLI tables, which are associated with the lowest mortality later in life, are also associated with favorable reproductive outcome earlier in life. Thus, the subcommittee has no scientific basis on which to accept or reject any of the existing reference standards for evaluating prepregnancy weight-for-height status, but it has adopted the BMI ranges shown in Table 4-2 to define four weight-for-height categories.
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From page 82... ...
INTERPRETATION OF RESEARCH INVOLVING GESTATIONAL WEIGHT GAIN In interpreting studies bearing on the health implications of gestational weight gain, it is necessary to pay careful attention to definitions, which suffer from uncertainties in three areas: (1) the method of designating prepregnancy weight, (2)
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From page 83... ...
83 Cal o ._ C)
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From page 84... ...
84 Cal ~ ._ i: V, C)
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From page 85... ...
85 o - ~ - 'e ~ ~ .= c ~ ~ c o ~ ~ ~ ~c,, ct o C C;~ C,)
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From page 86... ...
Increasingly, both researchers and clinicians are expressing gestational weight gain relative to either the observed or desirable prepregnancy weight (Method 4) or some recommended weight gain (Method 5)
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From page 87... ...
Weights determined at the first prenatal visit during the first trimester of pregnancy have been used to estimate total weight gain and earlygestation weight gain, but they do not necessarily reflect prepregnancy weights. Although average weight gain in the first trimester is small relative to that in later periods of pregnancy, individual variation may be considerable.
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From page 88... ...
Including the Fetus in Total Weight Gain Total gestational weight gain includes the products of conception as well as maternal tissue (Method 1 in Table 4-3~. The definition may lead to problems of misinterpretation of studies relating maternal weight gain to birth weight.
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From page 89... ...
Comparison of Gestaitonal Weight Gain with Reference Standards The expression of maternal weight or weight gain relative to a reference standard is especially useful if initial weights were taken after the first trimester of pregnancy and total or cumulative weight gain could not be calculated. One approach is to express weight at a given gestational age relative to prepregnancy body weight or desirable body weight (Method 4 in Table 4-3~.
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From page 90... ...
occurs at the upper end of the range of prepregnancy weight for height. Women at 120% of the reference weight would be advised to gain no weight during pregnancy, and those over 120% of the reference weight would be advised to lose weight during pregnancy.
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From page 91... ...
This is also the preferred way of expressing gestational weight gain when studying its effect on length of gestation or risk of premature delivery. Since premature delivery will shorten the time over which weight gain occurs, there is a need to express weight gain in a way that is independent of the length of gestation.
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From page 92... ...
The extensive standardized data collection instrument developed for these two systems includes questions on prepregnancy weight and height as well as total gestational weight gain and length of gestation (from LMP)
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From page 93... ...
· Gestational age should be estimated from the date of onset of the woman's last menstruation, preferably supplemented by estimates based on the obstetric clinical examination and perhaps by early ultrasound. · A weight-for-height category is derived from the patient's height and prepregnancy weight.
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From page 94... ...
1982. Anthropometric assessment of nutritional status in pregnant women: a reference table of weight-for-height by week of pregnancy.
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From page 95... ...
240 pp. Society of Actuaries/Association of Life Insurance Medical Directors of America.
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