**1. Introduction**

Achieving adequate pregnancy weight gain (PWG) is critical to optimize infant and maternal outcomes [1]. In developed countries, excessive pregnancy weight gain (PWG) is more likely [2–6] while women in lower-resource countries are more likely to experience inadequate PWG [7–9]. Inadequate PWG is mainly associated with poorer infant outcomes, preterm

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

birth, suboptimal infant birth weight [10–12], and greater risk of infant death [13]. Excessive PWG is also associated with negative infant outcomes (e.g., excessive infant birth weights [11, 14]), but in mothers, it increases the likelihood of delivery complications including cesarean delivery [14–16], postpartum weight retention [11, 17], and subsequent obesity [18–20]. In the longer term, inadequate and excessive PWG appear to alter the fetal intrauterine environment, resulting in obesity in childhood [21–23], adolescence [24, 25], and type 2 diabetes, and atherogenic profiles in adulthood [26, 27]. Therefore, optimizing PWG improves not only maternal health but that of the next generation.

Within a week of conception, the placenta begins to secrete another new hormone, human placental lactogen (hPL), thought to influence several metabolic processes associated with PWG. hPL blunts maternal insulin actions to ensure that sufficient protein and other energy sources are available to the fetus. The rate of HPL secretion parallels placental growth resulting in increasing insulin resistance making increased nutrition available to the fetus as the pregnancy progresses. In addition, hPL promotes maternal lipolysis which increases the circulating levels of free fatty acids to accommodate fetal nutritional and maternal metabolic needs [33, 34]. If a lipid panel (cholesterol, triglycerides, and other lipid fractions) is done for some reason during pregnancy, midwives and health-care workers should expect that levels will be elevated. This is evidence of the increased availability of energy being made available

Pregnancy Weight Gain: The Short Term and the Long Term

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Increased levels of progesterone and estrogen, both steroid hormones, contribute and respond to changes in PWG. Both hormones are initially synthesized by the corpus luteum of the ovary until about 7–9 gestational weeks when a "luteal-placental" shift occurs and the placenta takes over their production [35]. Increased hormone levels of estrogen influence carbohydrate, lipid, and bone metabolism [29] and promote growth of the uterus and breast tissue. High levels of progesterone ("pro-gestation") maintain the pregnancy by keeping the distended uterus in a quiescent state and suppress the mother's immune response to the fetus so that it is not rejected. Progesterone and estrogen contribute to the decrease in maternal vascular resistance to accommodate the notable increase (40–50% above her baseline) of maternal blood volume for better transit of nutrients and oxygen [33, 35]. Increased maternal blood volume contrib-

Pyrosis (heartburn) affects 50–80% of women in late pregnancy. It occurs when progesterone relaxes the lower esophageal sphincter (opening) and a burning sensation occurs as the acidic content of the mother's stomach irritates the esophagus [33]. In some cultures it is believed that mothers with heartburn in pregnancy will have infants with thick heads of hair! Nonpharmacologic approaches for women with heartburn include advice to eat smaller, more frequent meals, avoid trigger foods (e.g., high in fat or spicy foods), and avoid eating too close to bedtime or at times that they plan to be recumbent. The first-line pharmacologic approach is oral antacids containing cations of sodium bicarbonate (baking soda), calcium carbonate (TUMS), or magnesium salts which are widely available in stores and clinics. Antacids that contain calcium or magnesium are recommended as calcium is often needed and magnesium may reduce the incidence of preeclampsia [36]. If these do not work, women may also be given more targeted agents like H2 receptor agonists (cimetidine or ranitidine) or proton-pump inhibitors (omeprazole) by their midwife or clinic [33, 36]. Although no woman wants to experience heartburn in pregnancy, she can be reassured that it may stimulate more

healthy eating behaviors and therefore may limit the possibility of excessive PWG.

Pregnancy is a teachable moment in which women are more likely to adopt risk-reducing behaviors and to pursue learning about their health and its effects on the growth and development of the fetus [37–39]. Midwives and other health-care workers are well positioned to provide accurate advice and counseling on PWG that can positively impact the outcome of the pregnancy. In a study of Hispanic women in Los Angeles, 18.8% of the women did not recall any discussions about PWG with health-care providers during pregnancy. Among those who had such discussions, only 42% reported receiving weight gain advice within the Institute of Medicine (IOM)

utes to PWG as does increased extracellular volume (edema).

to the fetus during pregnancy!
