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27. Nutrition in Labor
The experience of childbirth is unique to all cultures. This is a unifying factor for all cultures. Each woman’s experience and her need during labor are individualistic. Traditionally, special foods have been offered during labor, and some specific food has been discouraged as well. The general belief and practice was to give food during labor to enhance energy of the woman. This was also acknowledged by doctors of that era [1]. After the landmark publication by Dr. Curtis Mendelson in [2], which implied aspiration as a cause of maternal death, intake during labor was completely restricted. The practice of fasting during labor has been under scrutiny in recent times, primarily due to the potential detrimental effects of fasting. Primarily owing to modern-day anesthesiology, it is time to compare the disadvantages of fasting to risk of aspiration during anesthesia.
- 1.
To avoid oral intake during labor.
- 2.
To provide energy alternatively through intravenous route.
- 3.
Wherever possible to use local anesthesia over general anesthesia.
- 4.
Anesthesia should be administered by doctors trained specially in the particular field of specialization. (in those days, it was not mandatory that only anesthetists administer anesthesia.)
Since then birth settings have restricted oral intake during labor. The assumption was that gastric volume could be reduced by fasting. This view has been contended as there are no recent evidences to support this belief [3]. To compensate for the energy source during labor, intravenous glucose (or dextrose) has been suggested to be given [4–8]. The practice of intravenous glucose has been seen to have side effects in the mother such as low sodium, fluid overload, and increased blood glucose concentration. And moreover, there is very less evidence on the effectiveness of this approach [9]. On the contrary, it has been shown that intravenous fluids during labor may cause rebound low blood glucose in the baby, increased jaundice, and acidosis. These effects were observed more in compromised babies [10].
27.1 Physiology of Energy Utilization During Labor
During early days and for centuries before that, women were encouraged to eat during labor to avoid general weakness, delayed labor, and serious postpartum hemorrhage, as listed by DeLee. He revised his statement after Dr. Mendelson’s publication. The uterus uses glucose as its primary source of energy. Fat is another source of energy for the uterus. There is increased need for oxygen during labor [11], and hence there is increased necessity for glucose by women in labor [12]. During labor, to compensate for the increased demand, the liver increases glucose production. Metabolic processes are readjusted to suit the increased need for energy during pregnancy and labor. There is a dearth of research articles about specific nutritional needs of women in labor. It is suggested that the energy requirement during labor could be similar to that of moderate cardiac exercise.
Elevated ketones are seen during exercise and starvation. The same may happen as part of the physiological response during labor, especially while the mother is fasting. Much significance was not attached to this until associations were established between elevated ketone levels, longer labor, and maternal psychological stress [13]. It is however difficult to determine whether the longer labor hours is due to ketone production or vice versa. During long labor, presence of ketonuria should be taken as a sign of metabolic imbalance.
Due to the increased fetal energy requirements resulting in increased fat metabolism along with the pregnancy-induced hormone changes, pregnant women are prone to ketosis [14]. Kubli et al. [15] concluded that ketone synthesis is increased in women in labor who are subjected to prolonged fasting especially ß-hydroxybutyrate and acetoacetic acid. In the 1960s and 1970s, to overcome ketosis, women in labor were administered intravenous fluids with glucose or dextrose. When given in large doses aggressively, intravenous dextrose was shown to cause fetal lactic acidosis, newborn jaundice, and hypoglycemia. Hence this protocol was discontinued [16]. Presently there are no guidelines to manage ketosis of labor.
27.2 Effect of Oral Intake during Labor
27.2.1 Light Diet
Scrutton et al. [17] compared the effect of light diet with water and water only in regard to ketosis. The light diet consisted of food such as cereal, bread, butter/jam, low-fat cheese, fruit juice, and beverages with milk such as coffee, tea, and hot chocolate along with water. Ketosis was effectively prevented in the light diet group, and the mothers had significantly increased gastric volume. The end points measured included duration of labor, oxytocin requirement, Apgar scores of the newborn, and mode of birth. There was no statistical difference in any of the parameters; both arms of the study have no significant difference. The drawback of the study was that it wasn’t sufficiently powered enough.
27.2.2 Sports Drink
Kubli et al. in their study in 2002, which aimed to study metabolic effects during labor, compared isotonic “sports drinks” to only water during labor. The women in the study group were given 925 mL of sports drink that provided 28 kcal/dL (64 g/L or 6% carbohydrate solution), which also provided small amounts of plasma beta-hydroxybutyrate. The nonesterified fatty acids were measured at two points: (1) early labor and (2) end of the first stage of labor. The residual gastric volume was assessed using ultrasound 45 min after delivery. The study found that at the end of the first stage of labor, in the water-only group, plasma beta-hydroxybutyrate and nonesterified fatty acids had increased, and plasma glucose (P = 0.007) had decreased significantly. The other parameters studied, namely, maternal and neonatal outcome, gastric volume, incidence of vomiting, volume of vomit during labor or within an hour of delivery, duration of labor, rate of augmentation, mode of birth, Apgar scores, and umbilical artery and vein pH, were also similar in both groups. Hence the researchers concluded that there is a reduction in maternal ketosis without increase in gastric volume when isotonic drinks were given to women in labor.
27.2.3 Carbohydrate Solution
201 consecutive nulliparous women, with singleton in cephalic presentation in early labor (2–4 cm of cervical dilatation), were included in a randomized, double-blind, placebo-controlled trial by Scheepers et al. in [18]. The women in the study arm received a solution to drink which had 12.6% carbohydrate. The intake in the placebo group was on an average 300 mL, while the median intake in the study group was 400 mL. The carbohydrate solution was well tolerated. While the rate of abdominal delivery was significantly higher in the study group, 7% in the placebo group, and 21% in the study group (RR 2.9, 95% CI 1.29–6.54), there were no statistically significant differences in other parameters such as duration of labor or use of forceps or vacuum to assist vaginal delivery.
The same group [19] continued to study the effects of oral carbohydrate on maternal metabolism, fetal metabolism, and clinical outcomes. This study involved 202 women in advanced labor with 8–10 cm of cervical dilatation. The women in labor were given either a carbohydrate drink or placebo. Metabolic parameters were measured, in a subgroup of 28 women. In the carbohydrate group, instrumental delivery was not reduced (RR 1.1, 95% CI 0.9–1.30), though there was a marginal reduction in the cesarean section rate which however was not statistically significant (1% vs. 7%, RR 0.2, 95% CI 0.02–1.2). In the study group, there was an increase in maternal lactate and a reduction in maternal free fatty acids and a positive venous-arterial lactate difference in the umbilical cord. Though the placebo group had negative venous-arterial lactate difference in the umbilical cord, the differences in pH were comparable.
In an interesting parallel prospective randomized controlled trial, 190 singleton cephalic pregnancy in labor with 3–4 cm dilatation were assigned to either carbohydrate (intervention N = 87) or control (N = 90) group. The women in the intervention group were asked to have three dates with 110 mL water or three dates with 110 mL light tea without sugar or 110 mL orange juice drink. The primary outcome was to measure the duration of the active phase of labor. It was seen that there was a reduction in the active stage of labor in the intervention group (P < 0.05), but there were no significant differences in other maternal and neonatal outcomes. Hence the authors concluded that oral intake of carbohydrate could be an effective way of shortening the duration of second stage of labor in low-risk women.
27.2.4 Low-Fat Diet
In a prospective randomized controlled trial by O’Sullivan et al. in [20], 2426 nulliparous, nondiabetic women in labor with less than 6 cm cervical dilatation were included. One arm were given low-fat diets during labor and others water only. In this study, no significant difference was noted in terms of spontaneous vaginal delivery rate (44%), duration of labor (597 min vs. 612 min), cesarean delivery rate (30% vs. 30%), or incidence of vomiting (35% vs. 34%) between the study and control groups. Hence, the authors concluded that a light diet during labor did not alter obstetric, neonatal outcomes nor did it increase the incidence of vomiting.
27.2.5 Energy Drink
In another study by Kardel et al. [21] involving 213 healthy nulliparous women at gestational age of >36 weeks, extra energy was given to women in labor along with the self-regulated diet. The aim of the study was to know the effect of the extra energy on the duration of labor. The result showed that the median time to delivery in the intervention group was 9 h (61%) and the median time to delivery in placebo group was 58 h (58%). The difference in duration seen was not statistically significant. Hence, it was concluded that energy drink beyond self-regulated diet during labor was not essential.
27.3 Does Oral Intake Influence the Following?
27.3.1 Length of Labor
Two randomized controlled trials ([17, 18]) have found that intake during labor did not have any significant effect on the length of labor, as also seen in the studies mentioned above.
27.3.2 Nausea and Vomiting
One randomized controlled trial by Scrutton et al. in [17] observed an increase in the incidence of nausea and vomiting in women who had oral intake during labor. In this RCT, twice as many women who had light diet vomited compared to women who had water only (38% vs. 19%). Three other trials [15, 22, 23] did not find any difference in the incidence of nausea and/or vomiting in women who were allowed to have isotonic drinks during labor. In the sports drink group, mean plasma glucose remained unchanged, while it was less in the water-only group, and this difference was statistically significant.
27.3.3 Operative Birth
A study by Scheepers et al. in [18] found cesarean section rate to be higher in women who had carbohydrate drinks in labor as opposed to those drinking only water (21/102 = 21% vs. 9/99 = 9%), while in another trial by Kubli et al. in [15], the group did not see any difference in cesarean section rate between the carbohydrate and water-only groups (carbohydrate drink group, 6/30 = 20%, vs. water-only group, 8/30 = 27%).
27.4 Physiology of Gastric Emptying in Pregnant Women
Pregnancy is marked by the following features—reduced esophageal sphincter tone and reduced GI tract motility. The gastrin levels are found to be high during the late third trimester, labor, and also during the immediate postpartum period. The increase in size of the uterus as pregnancy progresses leads to increase in the intragastric pressure, especially in the third trimester [24], which makes the pregnant women more prone to regurgitation and aspiration. Any other factor that augments these physiologic changes such as GERD or COPD increases the risk of pulmonary aspiration, especially when general anesthesia is administered during operative birth [25]. In another study by Smith et al. in [26], contrary to the prevalent theory and practice, they concluded that there was no correlation between the volume of gastric content and the probability of pulmonary aspiration.
It has been shown in many studies that the stomach is never completely empty [27], but still, it is regular practice to insist on at least 6 h of fasting prior to surgical intervention to have an empty stomach. It has been suggested that contrary to the existing belief, fasting would result in accumulation of acidic secretion in the stomach thus increasing the gastric volume, which also may contribute to increasing the risk of aspiration [28]. A gastric pH less than 2.5 and/or a volume greater than 0.4 mL/kg would cause lung injury if aspirated [29]. In spite of this basic physiological information and multiple publications that have demonstrated that fasting does not reduce maternal morbidity by pulmonary aspiration, the practice of withholding food and fluids to women in labor continues to be in practice till now.
27.5 Aspiration as a Contributor of Pregnancy-Related Mortality
To know the extent of aspiration as a cause of maternal death is very pertinent at this juncture. Hawkins et al. analyzed data from CDC during the period 1979–2002 which reported 5946 pregnancy-related deaths [30]. Out of the 5946 cases of maternal mortality, 56 were attributed to administration of anesthesia. It was observed that there was a decreasing trend in the case fatality rate for general anesthesia. In the period 1991–1996, the incidence of anesthesia-related mortality was 16.8 for every 1 million general anesthesia administered, while it had reduced to 6.5 for every 1 million general anesthesia in the period 1997–2002. The decrease in the fatality rate has been suggested due to increased standards of care and improvements in anesthesia.
In a detailed analysis of maternal mortality in the USA between the period 1998 and 2005, Berg et al. [31] found 14.5 deaths per 100,000 live births (12.0 per 100,000 live births in 1998 to 16.8 per 100,000 live births in 2005). This was higher than the previous 20 years of the Pregnancy Mortality Surveillance System. It was also noted that there was a change in the trend. While a decline in maternal mortality due to hemorrhage and hypertensive disorders was seen, an increase was noted in maternal mortality due to medical conditions, particularly cardiovascular. The following causes each contributed to 10–13% of maternal deaths—hemorrhage, infection, thrombotic pulmonary embolism, hypertensive disorders, cardiomyopathy, cardiovascular conditions, and non-cardiovascular medical conditions. During the period 2003–2005, specific check boxes were introduced to mark the cause of maternal mortality. The study proposed that the increase in maternal mortality reported could be due to improved methods to identify pregnancy-related deaths and determine the cause of mortality. The interesting fact noted in this population study was that anesthesia-related maternal mortality was the lowest—1.2%. A recent Cochrane review by Paranjothy et al. [32], concluded that medications to increase gastric pH and gastric emptying have been found to be effective in women undergoing general anesthesia for cesareans.
Various studies that have been published in this area have identified the following as risk factors of aspiration in cases of anesthesia-related deaths, namely, obesity, poor preoperative general condition, emergency procedures, hypertension, embolism, and hemorrhage [26, 27, 33]. These studies can help to make an algorithm to identify patients at risk and provide individualized management.
27.6 Safety
27.6.1 For the Mother
27.6.1.1 Mortality
Obstetrical anesthesia has advanced considerably since the 1940s. Though there have been marked improvements in drugs and monitoring in general anesthesia, in obstetric scenario, there has been definitive shift from general anesthesia to regional anesthesia. The present scenario is different to the era of Mendelson when (a) women were encouraged to eat heavy meals during labor, (b) anesthetic techniques were also different from present-day modern anesthesiology, and (c) anesthesia was administered by untrained doctors.
Confidential inquiry into maternal mortality in the UK, in which every maternal death from the 1950s was investigated on individual basis, has not shown any link between maternal mortality and women eating and drinking in labor. In another study, the majority of maternal deaths were said to be associated with older anesthetic techniques and inexperienced practitioners between the 1960s and the 1990s [34].
27.6.1.2 Excessive Fluids
While solid food restriction has been in vogue for women in labor, water-only diet has been allowed. From the studies that have already been quoted in this chapter, it has been shown that excessive water (around 7–8 L) intake in women in labor has adverse effects on the mother and baby; some newer case reports have even reported hyponatremia in babies [35]. Obstetricians, midwives, and all involved in antenatal care of women need to be aware of this risk and make parents aware of it.
27.6.2 For the Baby
No difference in Apgar scores or NICU admissions in babies was noted between women who were eating and drinking in labor and women who were on water-only or carbohydrate drinks. Hence, there is insufficient data to conclude on the impact of maternal intake on the outcomes of the baby [18].
27.7 Current Practice
Hawkins et al. in [36] surveyed 740 US hospitals regarding the hospitals’ policy on oral intake during labor. They found that in most hospitals, clear fluids were given during latent phase of labor, but 6% of hospitals had nil oral policies. During the active phase, women were restricted to only sips of fluid or ice chips, but 18% of hospitals had nil oral policies. Only 8% of hospitals had policies that permitted women in labor to have food during the latent phase. Almost all hospitals were found to have nil oral policies during active phase of labor.
Britain, Australia, and the Netherlands were found to have more liberal policies in regard to food intake during labor. A survey of the prevalent policies in England and Wales found that 96% of maternity units allowed oral intake. 67.2% of hospitals allowed fluids only, and 32.8% gave fluids and food [37]. While in New South Wales, Australia, 60.5% of women in labor were allowed food and fluid [38]. In the Netherlands, 67% of midwives and 73% of obstetricians allowed women in labor to choose food or fluid of their choice during labor. Survey of all births and cesarean births between the period 1983 and 1992 in the Netherlands found that the rate of aspiration which led to maternal mortality was as low as 0.018 per 1000 cesarean births and 0.001 per 1000 among all births. Interestingly, the rate of fatal aspiration was the same in the more liberal Netherlands as compared to the more restrictive USA and Great Britain [39].
27.8 What Women Want?
During early labor, there are elevated levels of prolactin which stimulates maternal appetite, but, with progression of labor, increase in oxytocin secretion reduces the desire to eat [40]. This would comprise the normal physiological changes related to appetite in labor.
In the context of woman-centered care, it would be important to know how women feel about intake restriction during labor. What is the pattern of eating and drinking women would prefer while undergoing one of the most important stages of their life? There are many surveys and trials which have attempted to address these questions. Safety of liberalized policies has been the core of such surveys and studies. Frye in 1994 suggested that eating in labor makes the woman feel normal and healthy, by helping her to be energetic, thus avoiding exhaustion. The psychosocial aspect of fasting should definitely be considered. Recent surveys have suggested that women preferred the process of labor to be comfortable and were not happy by the restriction of food and drink [41].
There have been winds of change. Surveys in the early 1980s in the UK and the USA revealed that not many consultants were averse to allowing women in labor to have food and fluids. But few surveys in 1990 and later have shown that some sort of food and fluids, usually water, was allowed during labor [9]. There is no strong evidence to show that liberalization of food intake policy during labor has compromised the safety of women in labor in the UK.
27.9 Current Recommendation
The American Society of Anesthesiologists currently does not recommend fasting in low-risk patients. They have stated that as parturient aspiration rates are nearly extinct due to advancements in anesthesia practice, identification of high-risk populations becomes essential. Early epidural placement in patients with preeclampsia and eclampsia and in obese patients is suggested [42]. ASA has suggested that restrictions should be on “case-to-case basis” depending on each patient’s at-risk factors for aspiration and in women who are more likely to have operative birth. The American Society of Anesthesiologists recommends complete restriction of solid foods in women in labor.
The statement of the American College of Obstetricians and Gynecologists was published in 2009–2015. It states that those patients who are undergoing cesarean delivery but without any complications may have some amount of clear liquids up to 2 h before induction of anesthesia. However, AJOG recommended against particulate-containing fluids. The recommendation of AJOG is similar to ASA in determining intake restriction in women at risk. It also stated that since there was insufficient evidence on the safe period of fasting after solid intake, any patient posted for elective cesarean delivery or elective postpartum tubal ligation, a minimum preoperative fasting for 6–8 h was recommended. As it is difficult to predict non-elective procedures such as cesarean section, it was suggested to avoid solid foods in laboring patients [43]. Another recent study also recommended that women in labor with low risk of aspiration or operative birth may be given solid food basically due to advancements in anesthesia [44].
Restriction of food and fluids during labor does not have any benefit nor does it increase risk in low-risk women.
Differences in rates of abdominal delivery, operative vaginal birth, and 5-minute Apgar score were not statistically significant between various studies or placebo groups.
No case of regurgitation was reported in women in whom general anesthesia was administered for operative birth, in any of the studies included in the Cochrane review.
Most studies did not study maternal experience, expectation, and hypoglycemia.
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