Which is the expected total weight gain for a client with a singleton pregnancy during the first trimester?

Variability in Weight Gain

The BMI-specific target ranges for pregnancy weight gain are relatively narrow, but a very wide range of gain actually occurs. In a California study, for example, only 50% of the mothers who had an uncomplicated pregnancy with a normal birth-weight infant gained the recommended range of weight, with the remainder gaining more or less. Because a substantial amount of the variation in weight gain is due to physiological variability and prepregnancy BMI, deviation from the recommended range may not necessarily be cause for concern. However, it is especially important to assess the dietary patterns and other behaviors of women whose weight gain is unexpectedly high or low.

Defining gestational weight gain

GWG is a complex and unique biologic phenomenon, which supports the growth and development of the fetus.32 GWG is made up of maternal components (including fat mass, fat-free mass, and total body water), placenta components (including placental weight, placental growth, placental development, and placental composition), and fetal components (amniotic fluid and fetal growth; both fat mass and fat-free mass).32 The total amount of weight gained in normal-term pregnancies differs from woman to woman.32 However, some generalizations can be made about the patterns of GWG and the impact on pregnancy outcome. Data from singleton pregnancies in the United States suggested that adult women with a recommended BMI who delivered at full term had a GWG ranging from 10.0 to 16.7 kg, whereas adolescents had a higher GWG (14.6–18.0 kg).32 There was also an inverse association between maternal prepregnancy BMI and GWG; the higher the BMI, the lower the total GWG.32 The pattern of GWG also differs by trimester of pregnancy and is generally higher in the second trimester.32

There are multiple factors that contribute to the amount of weight gained during pregnancy, which may explain some of the differences observed in the patterns of weight gain between subgroups of the population. Potential determinants of gestational weight gain include social and environmental factors (e.g., culture, family, and living environments), maternal factors (e.g., genetics, ethnicity, and comorbidities), and energy balance.32 A summary of the determinants, and interactions between determinants, is shown in Fig. 13.1.

Abstract

Excessive gestational weight gain (GWG) has significant public health implications due to the increased risk of birth complications and cesarean section, and ultimately, increased rates of long-term obesity for the mother. Furthermore, exceeding GWG recommendations is harmful to the offspring as well, conferring increased risk of childhood and adult obesity. This suggests that pregnancy is a critical period of time to affect weight outcomes across generations. Unfortunately, the majority of US women exceed the Institute of Medicine guidelines for recommended GWG. In this chapter, we discuss prenatal physical activity, including current recommendations, pregnant women’s levels of activity, and interventions to attempt to improve engagement. In addition, we discuss other predictors of GWG, evidence for GWG interventions, and recommendations for future approaches.

24.7 Preventive Strategies Start In-Utero

Because GWG of the mother is known to be an important predictor of obesity later on in the child; prevention strategies could start early in the fetal life by assuring that the mother gains weight as per the BMI-specific GWG recommendations in accordance with current IOM 2009 guidelines [28]. Further, healthy weight gain and healthy lifestyle habits could optimize pregnancy outcomes and prevent GDM. This reduces the chances of having an LGA baby, which itself increases future risk of obesity.

Based on the majority of prenatal lifestyle intervention studies, however, have definite conclusions that suggests prevention of excessive GWG that may be linked to lower incidence of high birth weight cannot be established. However, all of these studies had the primary outcome of preventing excessive GWG and were underpowered to see the effect on the secondary outcome of preventing high infant birth weight. The study by Mottola et al. reported that, in overweight women, a significantly lower percentage of babies born weighing between 4 and 4.5 kg was found in the group following intense lifestyle intervention to control GWG, compared to controls (3.2% versus 18%, resp.; P = .048) [29]. The most effective way of preventing excessive GWG is not clear, but a combination of prenatal interventions including nutritional counseling, supervised PA sessions, and a behavioral change approach might be the most successful.

Importantly, SGA babies with rapid postnatal weight gain are at very high risk for future obesity and demands preventive strategies at this step by promoting breastfeeding and delaying introduction of complementary foods and high-protein intake diet during early childhood.

11.4.2 Gestational Weight Gain

The optimal pattern of gestational weight gain is not known. In 1990 the U.S. Institute of Medicine (IOM) report concluded that gestational weight gain was an important determinant of fetal growth and set guidelines for weight gain in women of different prepregnancy BMIs [54]. These guidelines were updated by the IOM in 2009 [55] based on a review of a large body of primarily observational evidence of the relationship between gestational weight gain and short- and long-term health outcomes for the mother and child. However, women often gain gestational weight outside the recommended ranges, and there is evidence that the prevalence is increasing [56], even in the United States where the IOM guidelines are promoted [57, 58]. This has raised concerns about the consequences of excess gestational weight gain, including the long-term effects it may have on the offspring [55, 56]. There is strong observational evidence to support an association between greater gestational weight gain and increased child obesity. In 1044 mother-child pairs from Project Viva, the offspring of mothers who had higher gestational weight gain were more likely to be overweight at the age of 3 years (OR: 1.30, 95% CI: 1.04, 1.62 for each 5 kg weight gained) [58]. Adjustment for a range of confounding factors, including glucose tolerance and duration of breastfeeding, made little difference to this finding, but adjustment for parental BMI strengthened the association (OR: 1.66, 95% CI: 1.31, 2.12).

The impact of excess gestational weight gain on offspring obesity risk is also evident in later childhood years, adolescence, and adulthood. In a metaanalysis of 12 studies [59], stratified by offspring life stages of < 5 years, 5–18 years, and 18 + years, the offspring of women who had excess gestational weight gain were 1.4 times (95% CI: 1.23–1.59) more likely to develop obesity than the offspring of women whose gestational weight gain was adequate. The offspring of women who gained inadequate gestational weight had a lower risk of developing obesity (RR = 0.86; 95% CI: 0.78–0.94). The associations were similar regardless of offspring life stage, suggesting that excess gestational weight gain is associated with offspring obesity in both the short and long term. A study of 2432 Australians attempted to quantify the relationship between gestational weight gain and offspring adiposity, and found that offspring at 21 years of age were 0.3 kg/m2 heavier for each 0.1 kg per week greater gestational weight gain, and these associations were independent of maternal prepregnancy BMI [60].

However, the association between gestational weight gain and child obesity risk may be complex. Some evidence suggests that maternal BMI may have an interactive effect on the association between gestational weight gain and child obesity, and this may be different according to child life stages. For example, Oken and colleagues have also shown effects of gestational weight gain on offspring overweight in older children, aged 9–14 years [61]. Before taking account of maternal BMI, a U-shaped relationship was described between gestational weight gain and adolescent adiposity, such that higher rates of obesity were observed in adolescents born to mothers in the lowest and highest categories of weight gain. This is consistent with findings in mother-daughter dyads from the Nurses Health Study II where low and high gestational weight gains were both associated with obesity in the daughters studied at the age of 18 years [62]. However, the role of maternal BMI differed between these two studies. In the younger population, adjustment for maternal BMI changed the association, resulting in a positive linear relationship between gestational weight gain and child BMI, such that low gestational weight gain was associated with a lower risk of offspring obesity. In contrast, the U-shaped relationship found in older adolescents was not changed by taking account of maternal BMI [62]. An important finding from the Nurses Health Study II was that there was an interactive effect of weight gain and maternal BMI, as the association between low and high gestational weight gain and obesity in the daughter was modest among women of normal weight but more marked among mothers who were overweight before pregnancy.

More recent evidence also points toward differential effects of the rate of gestational weight gain at different periods in pregnancy. In a metaanalysis of four studies, higher rates of gestational weight gain in early and midpregnancy consistently had stronger adverse effect on offspring obesity outcomes [63]. For example, a UK study of 5154 mother-child pairs found that greater gestational weight gain during the first 14 weeks of pregnancy was associated with greater child adiposity at 9 years [64]. Similar findings were observed in a Dutch study of 5908 mother-child pairs where greater early pregnancy weight gain was associated with higher child BMI and fat mass at 6 years, and these findings were independent of maternal weight gain before pregnancy and weight gain during other trimesters [65]. The optimal pattern of gestational weight gain has yet to be defined. Not all studies have shown an effect of weight gain on adiposity in the offspring [47, 49], and further studies are needed to determine how variations in the pattern and the amount of weight gained in pregnancy impact on childhood body composition.

Recommended Weight Gain in Pregnancy

The target weights for gestational weight gain (GWG) were based on the recommendations provided by the Institute Of Medicine (IOM), ACOG and National Institute of Diabetes Digestive and Kidney Diseases (NIDDK) [9–12]. Obese women (BMI>30 kg/m2) were recommended a total weight gain of 5–9 kg in pregnancy and a mean weight gain of 0.22 kg/week (0.18–0.27 kg) in the second and third trimesters [10]. The recommendations were based on evidence from population-based cohort studies that evaluated the association between weight gain in pregnancy for women with various BMI and maternal and foetal outcomes. The risk of adverse outcomes varies with the various classes of obesity I (BMI 30–34.9 kg/m2), II (BMI 35–39.9 kg/m2) and III (BMI≥40 kg/m2). The risk of adverse outcomes was minimal for a GWG of 4.5–15.5 kg for obesity class I and 0–4.1 kg for obesity classes II and III. The NICE in United Kingdom refrained from providing recommended ranges for weight gain due to limitations in the evidence and concerns about the generalisability of the results to the UK population.

Variability in Weight Gain

The BMI-specific target ranges for pregnancy weight gain are relatively narrow, but a very wide range of gain actually occurs. In a California study, for example, only 50% of the mothers who had an uncomplicated pregnancy with a normal birth-weight infant gained the recommended 12.5–18 kg, with the remainder gaining more or less. Since a substantial amount of the variation in weight gain is due to physiological variability and prepregnancy BMI, deviation from the recommended range may not necessarily be cause for concern. However, it is especially important to assess the dietary patterns and other behaviors of women whose weight gain is unexpectedly high or low. The IOM Implementation Guide for weight gain recommendations provides helpful information on the assessments that should be used.

High Energy Intake and Excessive Gestational Weight Gain

At the other end of the spectrum, overnutrition leads to excess gestational weight gain, which increases offspring risk of obesity and metabolic dysregulation. A wealth of research demonstrates that higher gestational weight gain predicts offspring adiposity at birth (Deierlein et al., 2011), in childhood (Oken et al., 2007; Perng et al., 2014), adolescence (Oken et al., 2008b), and adulthood (Hochner et al., 2012). Many of these studies were able to establish this association independently of mother’s prepregnancy weight, and maternal/child shared environmental and lifestyle characteristics. Excess gestational weight gain is also correlated with a cluster of pernicious metabolic risk factors in offspring, including elevated blood pressure, insulin resistance, and altered adipocytokine profiles (Dello Russo et al., 2013; Fraser et al., 2011; Perng et al., 2014). In some cases, these changes were independent of the higher adiposity. In addition to the total amount of weight gain during pregnancy, the timing of weight gain may also have repercussions. Greater gestational weight gain during the first trimester has also been linked to higher offspring BMI (Margerison-Zilko et al., 2012) as well as biomarkers of cardiovascular risk at 3–5 years (Karachaliou et al., 2014), suggesting that interventions aimed at moderating weight gain early in pregnancy could benefit both the mother and infant.

Protein/energy supplementation

The effect of balanced protein/energy supplements for pregnant women on gestational weight gain and pregnancy outcomes was assessed on a Cochrane systematic review. Preeclampsia prevention was evaluated in three trials involving 516 women, with no significant beneficial effects (RR: 1.20; 95% CI: 0.77–1.89). However, these trials had methodological flaws, alternate allocation, and large lost-to-follow-up for the main outcomes, so results should be taken cautiously. In another Cochrane systematic review, only one trial involving 782 women evaluated preeclampsia prevention when isocaloric balanced protein/energy supplements were given to underweight pregnant women, showing no effect (RR: 1.00; 95% CI: 0.57–1.75).

Synopsis of Treatment Options