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From page 195... ... 6 Consequences of Gestational Weight Gain for the Child The emphasis of the report Nutrition During Pregnancy (IOM, 1990) was on the short-term consequences of gestational weight gain (GWG) Read the entire page →
From page 196... ... 196 WEIGHT GAIN DURING PREGNANCY mental data from randomized controlled trials in humans, however, impedes efforts to determine how much of any observed association is causal. In the following discussions, inferences regarding causality were made using the best data available in consideration of plausible biologic mechanisms, susceptibility to confounding and other aspects of the study methodology, and patterns of results. Read the entire page →
From page 197... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 197 factors ranging from the social/built/natural environment (macro) through behavior, physiology, and genetics (micro) Read the entire page →
From page 198... ... 198 WEIGHT GAIN DURING PREGNANCY differ from other animal species in duration of pregnancy, placentation, and other important factors, the importance of the findings from animal studies lies not in the specific interventions but rather in the general principle that altering the supply of nutrients, hormones, and oxygen to the growing embryo and fetus or exposing them to stressors and toxicants can have longterm effects. Much of this animal research has focused on obesity-related outcomes such as adiposity, fat distribution, sarcopenia, insulin sensitivity, glucose intolerance, and blood pressure. Read the entire page →
From page 199... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 199 comes include stillbirth and birth defects. In contrast, neonatal body composition is included in the discussion of long-term outcomes because of the hypothesis (still unproven, however) Read the entire page →
From page 200... ... 200 WEIGHT GAIN DURING PREGNANCY Presumably through developmental programming mechanisms, increased fetal adiposity also results in increased adiposity in the growing child. Other fuels besides glucose may also be involved. Read the entire page →
From page 201... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 201 mal experiments it is also possible to produce offspring that have insulin resistance, features of the metabolic syndrome, and diabetes, including GDM, by reducing energy or macronutrient intake of the mother during pregnancy. This situation can also result in intergenerational amplification of obesity and its consequences. Read the entire page →
From page 202... ... 202 WEIGHT GAIN DURING PREGNANCY EFFECTS ON NEONATAL MORBIDITY AND MORTALITY There is a substantial literature on prepregnancy BMI and neonatal morbidity and mortality; maternal prepregnancy BMI is strongly associated with infant mortality and a number of other clinically important outcomes, including stillbirth and preterm birth (Figure 6-2) Read the entire page →
From page 203... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 203 to confounding. These component relationships (prepregnancy BMI and GWG; and prepregnancy BMI and health outcome) Read the entire page →
From page 204... ... 204 WEIGHT GAIN DURING PREGNANCY Birth Defects The authoring committee of the IOM (1990) report did not identify any studies on the association between GWG and birth defects. Read the entire page →
From page 205... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 205 showing a diminishing effect of low GWG with increasing BMI. In the highest GWG group, the relative risks for neonatal mortality for underweight, normal weight, overweight, and obese women were 1.0, 1.2, 1.4, and 1.8, respectively, showing the exact opposite tendency -- excessive GWG was more strongly associated with neonatal death with increasing prepregnancy BMI. Read the entire page →
From page 206... ... 206 WEIGHT GAIN DURING PREGNANCY importance of the outcome but also because of the implications for the more voluminous literature on fetal growth and preterm birth. Although this study did not link GWG to those intermediate outcomes or intermediate outcomes to mortality, the strength of the patterns and their parallels with studies of fetal growth add credibility to the presumption that a causal chain from GWG to adverse birth outcomes to death is operative. Read the entire page →
From page 207... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 207 immutable, however, because health disparities are strongly influenced by social and behavioral factors. At the time of the IOM (1990) Read the entire page →
From page 208... ... 208 WEIGHT GAIN DURING PREGNANCY had infants that weighed 93 g less on average than controls. Fewer of the treated number developed GDM or had cesarean deliveries. Read the entire page →
From page 209... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 209 as total gain exceeds 25-30 pounds. Although the magnitude of association varied substantially across studies, in general the highest GWG category had roughly half the risk of an LBW infant compared to the lowest GWG category. Read the entire page →
From page 210... ... 210 WEIGHT GAIN DURING PREGNANCY First, Lof et al. Read the entire page →
From page 211... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 211 categories for underweight women, and a 3- to 4-fold gradient in risk for women in the other BMI categories (see Table 6-2) Read the entire page →
From page 212... ... 212 WEIGHT GAIN DURING PREGNANCY ity, smoking status, or other maternal attributes has been sparse, and the few studies summarized in the AHRQ review inconsistent. In addition to prepregnancy BMI, the only other factor that appears to impact the association between GWG and birth weight for gestational age is time during pregnancy that GWG occurs, with modest support for a stronger effect of GWG that occurs during the first or second trimester than during the third trimester GWG (Viswanathan et al., 2008) Read the entire page →
From page 213... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 213 a consistently increased risk of preterm birth among women in both the lowest and highest GWG categories. It is difficult to summarize the quantitative impact because the studies used varying definitions of high and low rates of weight gain and different analytic methods to characterize the relationship with preterm birth. Read the entire page →
From page 214... ... 214 WEIGHT GAIN DURING PREGNANCY The committee found no studies that directly link GWG to activation of the maternal or fetal HPA axis. However, several animal studies have linked periconceptional undernutrition to accelerated maturation of fetal HPA axis resulting in preterm delivery (Bloomfield et al., 2003, 2004; Kumarasamy et al., 2005) Read the entire page →
From page 215... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 215 direct causal relationship between GWG and preterm delivery guided the committee's approach to decision analysis in Chapter 7, which weighed the trade-offs of GWG with and without taking into account preterm delivery as an outcome. Read the entire page →
From page 216... ... 216 WEIGHT GAIN DURING PREGNANCY delivering term infants, an association that was independent of prepregnancy weight, gestational age, smoking, and family history of diabetes. Although these findings raise the possibility that higher GWG may lead to long-lasting adiposity in the offspring, more definitive evidence would come from studies addressing the relationship between GWG and body composition from birth onwards in populations from developed countries. Read the entire page →
From page 217... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 217 and poor breastfeeding outcomes, the committee identified no studies that addressed the relationship between GWG and lactation-related offspring outcomes. Long-Term Effects on Obesity Despite the importance of this issue, high-quality studies associating GWG with obesity and obesity-related health outcomes in childhood are only just beginning to be published. Read the entire page →
From page 218... ... TABLE 6-3 Published Studies (N > 1,000) Relating Total GWG to Child Obesity 218 Moreira et al., 2007 Oken et al., 2007 Oken et al., 2008 Wrotniak et al., 2008 Age at Outcome (y) Read the entire page →
From page 219... ... Maternal BMI Category WHO Categories IOM Categories Underweight NA NA 0.94 (0.71-1.23) Read the entire page →
From page 220... ... 220 WEIGHT GAIN DURING PREGNANCY 10,000 7-year-old term-born offspring of participants in the 1950s-1960s Collaborative Perinatal Project (see Table 6-3) Read the entire page →
From page 221... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 221 0.6 Without adjustment for maternal BMI 0.4 0.2876 With adjustment for maternal BMI 0.19 Child BMI z-score 0.2 0.18 0.0 –0.2 –0.2511 –0.4 –0.6 Less 10-14 15-19 20-24 25-29 30-34 35-39 40-44 45 or than 10 more Maternal Gestational Weight Gain (pounds) FIGURE 6-3 Associations of maternal gestational weight gain with child BMI z-score at ages 9-14 years, with and without adjustment for maternal prepregnancy Figure 6-3.eps BMI. Read the entire page →
From page 222... ... 222 WEIGHT GAIN DURING PREGNANCY Other Outcomes The following discussion summarizes the committee's evaluation of the evidence on a range of other, non-weight-related long-term offspring outcomes, including neurodevelopmental outcomes, allergies/asthma, and cancer. Neurodevelopment Alterations in fuel metabolism during pregnancy resulting from intended or unintended weight loss, fasting, or poorly controlled diabetes can cause ketonemia and/or ketonuria, which in turn can have consequences for the neurocognitive development of the infant (see Chapter 3) Read the entire page →
From page 223... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 223 and female infants. Watt and Strongman (1985) Read the entire page →
From page 224... ... 224 WEIGHT GAIN DURING PREGNANCY Long-term neurodevelopment in preterm SGA In preterm SGA infants, the majority of longitudinal studies reviewed by the committee focused on extremely premature (Feldman and Eidelman, 2006; Kono et al., 2007; Paavonen et al., 2007; Leonard et al., 2008) or very low birth weight (VLBW) Read the entire page →
From page 225... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 225 The overwhelming majority of studies reviewed support an association between preterm SGA and lower neurodevelopment in the longer term. Consistent with the studies on term SGA, many of the studies on preterm SGA did not properly control for key perinatal (e.g., asphyxia) Read the entire page →
From page 226... ... 226 WEIGHT GAIN DURING PREGNANCY in mobilization of maternal adipose tissue and possibly lean body mass. Although the gestational metabolic milieu or offspring outcomes of pregnant women who experience weight loss have not yet been addressed in the scientific literature, there have been several studies on associations between ketonemia or ketonuria, which can occur among pregnant women subjected to short-term fasting (see Chapter 3) Read the entire page →
From page 227... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 227 to controls with adequate GWG. In that study, maternal smoking (OR = 18) Read the entire page →
From page 228... ... 228 WEIGHT GAIN DURING PREGNANCY levels, providing some support to the estrogen hypothesis; however, higher GWG was associated with lower levels of maternal progesterone and of sex hormone-binding globulin (-0.7 percent [95% CI: -1.5, 0.0] at 16 weeks and -1.2 percent [95% CI: -2.0, -0.4] Read the entire page →
From page 229... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 229 weight gain predicts SGA. Both LGA and SGA are themselves markers of neonatal morbidity. Read the entire page →
From page 230... ... 230 WEIGHT GAIN DURING PREGNANCY LGA. Despite a limited number of randomized controlled trials, biological plausibility from animal models is strong. Read the entire page →
From page 231... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 231 position at birth, and neurodevelopment, obesity and related outcomes, and asthma later in childhood. Areas for Additional Investigation The committee identified the following areas for further investigation to support its research recommendations. Read the entire page →
From page 232... ... 232 WEIGHT GAIN DURING PREGNANCY Allen L Read the entire page →
From page 233... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 233 Cedergren M Read the entire page →
From page 234... ... 234 WEIGHT GAIN DURING PREGNANCY Gillman M Read the entire page →
From page 235... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 235 IOM (Institute of Medicine) Read the entire page →
From page 236... ... 236 WEIGHT GAIN DURING PREGNANCY Maffeis C., R Micciolo, A Read the entire page →
From page 237... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 237 Ong K Read the entire page →
From page 238... ... 238 WEIGHT GAIN DURING PREGNANCY Samuelsson A Read the entire page →
From page 239... ... GESTATIONAL WEIGHT GAIN FOR THE CHILD 239 Strang-Karlsson S., K Raikkonen, E Read the entire page →
From page 240... ... 240 WEIGHT GAIN DURING PREGNANCY Watt J Read the entire page →

From page 195...

... 6 Consequences of Gestational Weight Gain for the Child The emphasis of the report Nutrition During Pregnancy (IOM, 1990) was on the short-term consequences of gestational weight gain (GWG)