**3. Influences on pregnancy weight gain**

Midwives and health workers must consider that there are factors that influence PWG that are modifiable and those which are not modifiable. Further, modifiable factors such as food intake and physical activity are intertwined and are influenced by body habitus and age. It is also critical to be aware that appropriate PWG decreases the risk of pregnancy-related diseases such as gestational hypertension and gestational diabetes.

#### **3.1. Prepregnancy body mass index**

*2.3.3. Prepregnancy underweight*

48 Selected Topics in Midwifery Care

expense of fetal growth.

weight.

Maternal underweight (low BMI) at the onset and during pregnancy is a key determinant of poor fetal outcomes. The prevalence of low BMI is higher in developing nations with suboptimal access to food and greater risk for diarrheal diseases but is also present in developed nations in women with eating disorders or dependence on alcohol or other substances. One such negative outcome is intrauterine growth restriction (IUGR) or low birth weight (LBW, less than 2500 g). IUGR and LBW occur as a result of maternal, placental, and fetal factors [76].

Intrauterine growth restriction is associated with increased perinatal morbidity and mortality, and newborns with low birth weight have increased risk for the development of adult metabolic syndrome. One of the most cited examples of the long-term outcomes of maternal undernutrition is the Dutch Famine Birth Cohort Study [77]. In the winter of 1944/1945 the Nazi occupation turned a once prosperous country to one plagued by famine. Official food rations were below 1000 calories/day resulting in inadequate PWG and low birth weight infants. The offspring have been followed over subsequent decades. As middle-aged adults they were more likely to be obese [78] and have atherogenic lipid profiles [79]. This is explained using the fetal origin hypothesis [27], also referred to as the "thrifty phenotype" hypothesis, in which fetal reprogramming necessary to survive low food availability ended

Resting metabolic rate varies among pregnant women. Overweight women enter pregnancy with ample fat stores and their resting metabolism increases in an attempt to diminish further accumulation of fat stores [80]. Conversely, underweight women with limited food supply and the demands of hard physical labor frequently enter pregnancy with minimal maternal fat reserves. Their only option is to reduce their resting metabolic rate to conserve energy for their fetus [81, 82]. This permits delivery of a viable infant who may or may not be growth restricted, depending on the severity of the situation. Such strategies enable women to sustain a pregnancy under a wide range of conditions, including suboptimal nutrition. However, at some point, the physiological capacity of the body to adjust its metabolism and accommodate fetal growth will be compromised; nutrients are preferentially diverted to the mother at the

Health workers may want to consider the positive deviance approach based on the premise that solutions to a community's problem may exist within the community [83]. Positive deviance refers to the uncommon yet healthy practices that permit some persons to thrive while similarly positioned neighbors do not. One example was when program planners in Vietnam observed that mothers who fed their children less typical foods like shrimp and greens from the rice paddies instead of rice only were able to protect them from malnutrition [84]. A similar approach could be taken in communities in which access to sufficient energy, nutrient, and protein stores during pregnancy is suboptimal. There may prove to be "positive deviants" or women who have identified less common but effective means of optimizing pregnancy

up being a longer-term disadvantage when food was more abundant.

Achieving a normal prepregnancy BMI has a significant influence on appropriate PWG [1]. High (obese and overweight) prepregnancy BMI is a recurring key determinant of excessive gain among White [85–88], Black [89], Hispanic [90–93], and multiethnic women [2, 3, 94]. Specifically, overweight BMI has been the most commonly reported determinant of excessive PWG in all ethnicities [2, 4, 31, 88].

As noted previously, more women in developing countries are overweight or obese at the onset of pregnancy [68, 69] and therefore are more likely to have excessive PWG. Globally, the impact of excessive PWG may pose an even greater threat to maternal and infant longterm health in resource-poor settings undergoing various phases of the nutrition transition [95]. The nutrition transition is marked by shifts in diet from traditional foods to a more Western-type diet along with decreasing physical activity that propagates obesity and nutrition-related non-communicable diseases, such as cardiovascular disease and diabetes. As reproductive-age women in these settings were previously exposed to undernutrition and are now becoming overweight/obese, excessive PWG may further lead toward the heightened risk of maternal and offspring obesity and nutrition-related diseases [69].

Conversely, underweight BMI has been implicated in the increased risk of inadequate gain [31] but with less frequency in developed countries. Even with the "globesity epidemic," there are countries like India in which 42% of mothers are underweight and give birth to 20% of the world's babies. In poor-resource areas, women begin pregnancy with low BMI and gain little weight during pregnancy [7].

#### **3.2. Maternal age**

Adolescents and younger women [4, 31, 91, 96] are more likely to gain excessively. Though related to concurrent maturation, it is of concern because of the risk of postpartum weight retention and the potential for young women to move to a high BMI category by the next pregnancy [97]. There is less consistency in older women. Deputy et al. [31] reported that inadequate PWG was more likely in multi-ethnic women 35 and older while Puerto Rican women over 30 years of age were at 2.5 times greater risk for excessive PWG than younger women [90].

#### **3.3. Parity**

Even one pregnancy changes the fatness of a woman's body. One arm of the CARDIA study showed that White and Black women with a single pregnancy had pregnancy-related increased adiposity as compared to women who remained nulliparous [98]. Parity has a significant relationship to PWG independent of other known influences. In women from England, parity contributed most greatly to PWG followed by birth weight and BMI [85]. Adolescent primiparas gained 5.28 pounds more than multiparas [99]; had twice the likelihood of excessive PWG than multiparas [96]; and large multiethnic studies have also reported primiparity versus subsequent births as a covariate for excessive PWG [2, 3, 100].

at greater risk for excessive PWG. After delivery, women with excessive PWG are more prone to postpartum weight retention [11, 17] and more likely to become overweight or obese by the

Pregnancy Weight Gain: The Short Term and the Long Term

http://dx.doi.org/10.5772/intechopen.79066

51

Postpartum weight retention is defined as the weight change from preconception to the first year postpartum. Postpartum weight retention includes PWG, the early postpartum weight loss (from delivery to 6 weeks of postpartum), and late postpartum loss (subsequent weight changes in the postpartum year [114]. Early postpartum weight loss is from the combined weight of the infant, placenta, amniotic fluid, and water accumulated during pregnancy. Depending on the size of the infant and amount of water accumulated, the loss will be about 7 kg (15 lb). However, with an average PWG of 12–14 kg, 4–6 kg is the maternal fat gain, often referred to as "baby fat." Therefore, late postpartum weight loss requires loss of maternal fat that was acquired to support the pregnancy. With excessive PWG, there is even greater fat

The pattern of postpartum weight changes was examined in multi-ethnic women (n = 985) aged 18–41 years with 2 consecutive births between 1980 and 1990 [18]. Early postpartum weight change (6 weeks of postpartum) was similar in all four groups. However, the underweight and normal-weight groups lost more late postpartum weight even though their average PWG was greater. The higher (overweight and obese) BMI groups gained less during pregnancy but had diminished weight loss in the later postpartum period. This demonstrated that early postpartum loss is simply a reversal of physiological processes of pregnancy but

Another multi-ethnic study of young women aged 14–25 years (n = 427) reported that nearly two-thirds had excessive PWG. Of those, 33% of the young women moved to a higher BMI

Excessive PWG is the single greatest contributor to postpartum weight retention and subsequent life-long obesity and related co-morbidities [19, 113]. However, this is further compounded by acculturation/globalization, for example, acquisition of Western patterns of eating and more sedentary work [68, 69, 115]; ethnicity, as women of color are less likely to lose postpartum weight or to gain weight in the postpartum period [116, 117]; short interpreg-

Obviously, diminishing postpartum weight retention is greatly dependent on gaining appropriately during pregnancy and not "eating for two." Health workers and midwives should prepare pregnant women for exclusive breastfeeding for at least 6 months not only for the well-known health benefits to the baby but for the increased metabolic expenditure needed for lactation [120]. In women who exclusively breastfed for even 6 months, postpartum weight retention was eliminated in women with average PWG and any weight gain was reduced in

in an additional postpartum loss or 1.5 lb [97]. In the longer term, breastfeeding has effects on the mother's health beyond postpartum. Middle-aged women who never breastfed were compared to those who breastfed for even 3 months and had waist circumferences of 6.5 cm greater, 28% more central obesity, and therefore greater risk for cardiovascular disease [122].

[121]. Each additional week of breastfeeding resulted

category in the first-year postpartum resulting in 68% being overweight or obese [97].

next pregnancy [19, 112, 113].

deposition and the mother has yet more weight to lose.

late postpartum loss requires an alteration in maternal fat stores.

nancy interval [118]; and lower socioeconomic status [119].

all but women with BMI ≥35 kg/m<sup>2</sup>

#### **3.4. Hypertension and gestational diabetes**

A relationship between hypertension in pregnancy and excessive PWG has been observed in women of diverse ethnicities [3, 99, 101, 102]. Midwives and health workers must be aware of both modifiable and non-modifiable factors associated with pregnancy-related hypertension. Compared to White women, Black women consistently have more pregnancy-related hypertension independent of other factors [103–105]. In Hispanics, findings are less consistent: from reports of lower risk [106] to differential risk, higher risk for certain types of hypertension (e.g., preeclampsia but not gestational hypertension) [107]. In all ethnicities, pregnancy-related hypertension is more common in primiparas [102] and in women with a family history of hypertension [108].

High prepregnancy BMI and excessive PWG are modifiable factors that appear to have independent as well as synergistic influences on hypertension in pregnancy. Women with excessive PWG had a three-fold risk of hypertension and four-fold risk of preeclampsia compared to women who gained appropriately [109], and women with obese BMI had 2.5-fold higher odds of having pregnancy-related hypertension with excessive PWG compared to those who gained adequately [110].

Increased risk for gestational diabetes mellitus is associated with excessive PWG in early pregnancy [111]. However, once diagnosed with gestational diabetes, women may be more likely to gain inadequately [92, 93] or adequately [90] overall due to dietary and exercise modifications. Therefore, the diagnosis of gestational diabetes is really an opportunity to optimize pregnancy health through monitoring dietary intake and being more intentional to add physical activity as a means of controlling blood-sugar levels.
