Nutrition During Pregnancy Part I: Weight Gain, Part II: Nutrient Supplements (1990) / Chapter Skim
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8 Effects of Gestational Weight Gain on Outcome in Singleton Pregnancies
8 Effects of Gestational Weight Gain on Outcome in Singleton Pregnancies
Pages 176-211
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From page 176... ...
The subcommittee focused on the links between gestational weight gain and short-term pregnancy outcomes because data relating weight gain to long-term outcomes are relatively scanty, and there is no strong evidence indicating that weight gain affects long-term outcomes directly, i.e., without first affecting shorter-term outcomes. For example, several reports (Naeye and Chez, 1981; Singer et al., 1968; Tavris and Read, 1982)
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From page 177... ...
indicate that the relationship between gestational weight gain and perinatal mortality is strongly influenced by maternal prepregnancy nutritional status; i.e., there is evidence for important effect modification (see Chapter 2)
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From page 178... ...
, perinatal mortality began to rise with gestational weight gains in excess of 11.4 kg (25 lb) , which might be partially explained by a rise in the rate of high birth weight and a corresponding increased risk for shoulder dystocia and other complications of labor and delivery (see below)
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From page 179... ...
In an attempt to identify those infants at highest risk, many researchers and policymakers have compared infants with low birth weights (LBWs) , i.e., <2,500 g, with infants who weigh more.
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From page 180... ...
(B) Postneonatal mortality risks by race and birth weight, United States, neonatal survivors of 1980 live-birth cohorts.
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From page 181... ...
, meconium aspiration, clavicular fracture, brachial plexus injury, and birth asphyxia (Boyd et al., 1983; Koff and Potter, 1939; Modanlou et al., 1980~. Birth weight is a composite of two outcomes: the rate of fetal growth and gestational duration.
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From page 182... ...
, nor have they ensured accurate measurements of gestational age or controlled for confounding by short maternal stature or the postnatal nutritional and other environmental influences listed in Figure 2-2. Other Methodologic Caveats Interpretation of the literature relating gestational weight gain to fetal growth requires adequate consideration of several other factors: problems in measurement of length of gestation and gestational weight gain (Chapter
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From page 183... ...
Overstatements of the association of gestational weight gain and fetal growth are also expected unless birth weight is adjusted for gestational age, either by dividing net weight gain by the number of weeks of gestation or by using analytic methods to adjust for the expected gain at each week of gestation. The most appropriate measure of weight gain would be based on serial measurements of weight gain (i.e., the pattern of weight gain)
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From page 184... ...
for height among women with low gestational weight gain. Similar results were reported in several studies investigating mean birth weight (Abrams and Laros, 1986; Frentzen et al., 1988; Mitchell and Lerner, 1989; Naeye, 1981b,d; Seidman et al., 1989; Winikoff and Debrovner, 1981~.
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From page 185... ...
, although lower weight gains in such women are often compatible with optimal birth weights. The subcommittee has not identified an upper limit for this group.
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From page 186... ...
(The reported effect was 16.6- compared with 14.0-g birth weight per kilogram of gestational weight gain, respectively.) In addition, since weight does increase with age, older women might be protected to some degree against the adverse effects of low weight gains.
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From page 187... ...
The evidence also indicates that women with large gestational weight gains are at increased risk for highbirth-weight infants (Ounsted and Scott, 1981; Scholl et al., 1988; Udall et al., 1978) , which can secondarily lead to dysfunctional labor, midforceps delivery, cesarean delivery, shoulder dystocia, meconium aspiration, clavicular fracture, brachial plexus injury, and asphyxia (Acker et al., 1985; Boyd et al., 1983; Koff and Potter, 1939; Modanlou et al., 1980; Sandmire and O'Halloin, 1988~.
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From page 188... ...
in, _. -_ _, 0 5 10 15 20 25 Total Weight Gain, kg FIGURE 8-5 Full-te~m low birth weight of live-born singleton infants by total maternal weight gain and prepregnangy BMI of white, non-Hispanic mamed mothers in the United States in 1980.
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From page 189... ...
1 1 ~' High BMI (>26.0) .' 0.3 0.4 0.5 Net Weight Gain per Week, kg FIGURE 8-7 Full-term low birth weight of live-born singleton infants by net weight gain per week and prepregnancy BMI of white, non-Hispanic married mothers in the United States in 1980.
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From page 190... ...
Finally, the survey data also permit an analysis of weight gains associated with optimal fetal growth, defined here as a birth weight of 3,000 to 4,000 g and a gestational age of 39 to 41 weeks. The range for optimal fetal growth is based on a balance between lower infant mortality and higher birth weight at full-term and high rates of meconium aspiration, birth trauma, and asphyxia for infants with weights above 4,000 g.
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From page 192... ...
In France, Lazar (1981) reported that correlations between maternal weight gain and sex- and gestational age-adjusted birth weights were low and did not increase with advancing length of gestation.
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From page 193... ...
In Senegal, Briend (1985) found a negative correlation between maternal triceps skinfold thickness at fullterm and birth weight in full-term infants after controlling for maternal weight (also at full-term)
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From page 194... ...
Effects on Birth Length and Head Circumference The term fetal growth should be interpreted as indicating more than merely birth weight or birth weight for gestational age. In particular, other dimensions of fetal growth, especially body length and head circumference, have often been used as indices of pregnancy outcome.
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From page 195... ...
found an increased risk of preterm delivery in women with both normal and subnormal prepregnancy relative weights and total weight gains of <9 kg (20 lb)
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From page 196... ...
High BMI (>26.0) 1 1 1 1 0 5 10 15 20 25 Total Weight Gain, kg FIGURE 8-9 Preterm low birth weight of live-born singleton infants by total maternal weight gain and prepregnancy BMI of white, non-Hispanic married mothers in the United States in 1980.
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From page 197... ...
L _ High BMI (>26.0j 1 1 1 1 1 1 0.1 0.2 0.3 0.4 0.5 Net Weight Gain per Week, kg FIGURE 8-11 Preterm low birth weight of live-born singleton infants by net maternal weight gain per week and prepregnancy BMI of white non-Hispanic mamed mothers in the United States in 1980. From Kleinman (1990~.
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From page 198... ...
For women in the low and moderate BMI groups, there were significant associations between low total or net weight gain and the relative odds of preterm LBW. But the odds ratios were close to, and not significantly different from, 1 when the analysis was based on the more appropriate measure of net gain per weeL One important methodologic caveat should be kept In mind in interpreting studies linking gestational weight gain to gestational duration.
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From page 199... ...
Conception from June to October-a lean period of arduous work and reduced diet was associated with pregnancy loss primarily in the third trimester and, to a lesser extent, before and during the second trimester. Independent effects were reported both for reductions in prepregnancy weight as well as gestational weight gain, both of which were reduced during the lean period.
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From page 200... ...
(1955) did note a higher risk of toxemia in women with low prepregnancy weights for height who had low weight gains during the second trimester.
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From page 201... ...
, but the remarkable increase has been accompanied by rather modest increases in the rates of high birth weight (see Chapter 3~. Thus, even if larger gestational weight gains are partly responsible for the trend toward slightly larger infants, their contribution to complications of labor and delivery must be quite small.
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From page 202... ...
Nonetheless, the evidence from animal studies indicates that gestaizonal nutrition is less important than postpartum nutrition for lactation (Jenness, 1986; Kliewer and Rasmussen, 1987; Lodge, 1969; O'Grady et al., 1973; Sadurskis, 1988~. This evidence thus supports the notion that gestational weight gain in humans has little impact on subsequent milk quantity or quality.
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From page 203... ...
The 1-kg figure is based largely on data from older studies, however, and may underestimate weight retention associated with the higher gestational weight gains seen in recent years. Women
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From page 204... ...
SUMMARY A large body of evidence indicates that gestational weight gain is a determinant of fetal growth, although the magnitude of the causal impact is somewhat less than that usually reported because of the failure of previous studies to adjust total weight gain for fetal weight. Even after such adjustment, however, lower net weight gains are associated with an increased risk of IUGR and increased perinatal mortality (probably mediated by effects on IUGR)
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From page 205... ...
· Young adolescent and black mothers should be encouraged to strive for weight gains toward the upper range desirable for adult white mothers with similar prepregnancy weights for height and heights. REFERENCES Abrams, B.F., and R.K Laros, Jr.
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From page 206... ...
1989. The relationship between maternal weight for height and term birth weight in teens and adult women.
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From page 207... ...
1982. Neonatal mortality risk in relation to birth weight and gestational age: update.
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From page 208... ...
1981. Intrauterine growth: correlations of maternal nutritional status and rate of gestational weight gain.
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From page 209... ...
1981. Associations between maternal weight, height, weightfor-height, weight-gain and birth weight.
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From page 210... ...
1989. The effect of maternal weight gain in pregnancy on birth weight.
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From page 211... ...
1981. Anthropometric determinants of birth weight.
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