Statement on Oral Intake During Labor

Developed By: Committee on Obstetric Anesthesia
Original Approval: October 26, 2022

Since 1946, when Mendelson first published 66 cases of pulmonary aspiration pneumonitis (Mendelson’s syndrome) in obstetric patients,¹ providers caring for pregnant patients have recognized the risk of maternal regurgitation and aspiration during induction of general anesthesia. While maternal deaths from aspiration have declined significantly since the 1950s,² major aspiration events resulting in significant morbidity and mortality still occur.^1,3-6 This concern has led to a wide range of policies restricting oral intake during labor at the local level. Given the variation in patients’ medical conditions and pregnancy-related conditions, as well as indications for and duration of hospitalization, this committee statement aims to clarify recommendations regarding oral intake during labor.

Pregnant patients are at increased risk of pulmonary aspiration of gastric contents during induction of general anesthesia for several reasons:

1. Gastric emptying during labor has been shown to be delayed via ultrasonography, gastric emptying following a test meal and rate of absorption of orally administered acetaminophen, with a return to pre-pregnancy rates 18 hours after delivery.^7-11 Gastric emptying is up to 90% slower in laboring patients when compared to non-pregnant and term non-laboring patients.^12,13 Medications including intravenous opioids and high dose neuraxial opioids, either as a bolus or prolonged infusion, may further contribute to delayed passage of gastric contents.^14-17
2. Mechanical displacement of the stomach by the gravid uterus, as well as increased levels of circulating progesterone result in decreased lower esophageal sphincter tone and barrier pressure as early as the first trimester, allowing for reflux of gastric contents.¹⁸ Over 50% of patients experience gastroesophageal reflux disease in the 3rd trimester.¹⁹ This incompetence of the lower esophageal sphincter persists for 48 hours following delivery.²
3. Difficult intubation is associated with increased aspiration risk.²⁰ Pregnant patients have increased rates of both difficult and failed intubation (1:49 [95% CI: 1:55, 1:44)] and 1:808 [95% CI: 1:1,276, 1:511)], respectively).²¹
4. Most cases of cesarean delivery under general anesthesia are emergent in nature, which is also associated with increased aspiration risk.^22,23

Aspiration of solid food results in asphyxiation. Aspiration of liquids may be equally morbid, and severity correlates with the volume (> 25ml) or acidity (pH <2.5) of gastric contents.^1,2,10,24-26 Therefore, liberal oral intake during labor likely places parturients at increased risk of severe morbidity or mortality should general anesthesia be required. In addition, there is no difference in delivery outcomes including duration of labor, and rates of instrumental vaginal or cesarean delivery in patients who consume food during labor compared to those drinking only water.²⁷ Currently, there is insufficient scientific evidence to support the consumption of solid food during active labor. This committee recommends no change to the existing guidelines set forth by the American Society of Anesthesiologists (ASA) and American College of Obstetricians and Gynecologists (ACOG), stating consumption of solid food during active labor should be avoided.^28,29

Strict NPO policies on labor and delivery, however, have the potential to create unintended negative consequences including patient distress.³⁰ Thirst has been shown to contribute significantly to maternal discomfort during labor.³¹ In addition, patients in the 3rd trimester of pregnancy may experience accelerated starvation during prolonged periods of fasting, resulting in production of ketones, such as beta-hydroxybutyrate and acetoacetic acid.³² Carbohydrate and/or electrolyte containing sports drinks reduce ketosis without significantly increasing gastric volume, and therefore likely provide greater benefit than other clear liquids.^33,34  It is this committee’s opinion that patients should be offered clear liquids during labor, including isotonic sports beverages, water, ice chips, fruit juices without pulp, black coffee, and tea without milk or cream.

Regardless of stage of labor, patients at increased risk for regurgitation and pulmonary aspiration, as well as those who are likely to need a cesarean delivery for maternal or fetal indications may require stricter recommendations to include limiting the amount and type of clear liquids. Examples of such situations include but are not limited to poorly controlled diabetes, class 3 obesity (BMI ≥40 kg/m²), factors associated with an increased risk of failed intubation and non-reassuring fetal status.^35,36 (Table 1) Policies on oral intake during labor should be developed based on the recommendations outlined in this document, with consideration given to shared decision making and minimizing unintended negative consequences such as patient distress and discomfort.

Parturients are admitted to labor and delivery for a variety of reasons and for various lengths of time ranging from hours to days. This may lead to prolonged periods of restricted oral intake. Recent studies supporting elective term inductions have likely increased the number of patients subjected to such prolonged periods of restrictions on oral intake.³⁷ There is insufficient evidence to make a recommendation regarding more liberal oral intake during the "pre-labor" phase for patients presenting for elective induction of labor. In addition, determining when a patient transitions from the "pre-labor" phase to labor (latent or active) can be subjective and ambiguous. These factors make interpretation and implementation of specific recommendations for this group of patients by individual labor and delivery units difficult. Shared decision making and informed consent on oral intake during the pre-labor time period are encouraged.

Research is needed to better characterize the risks and benefits of oral intake during this "pre-labor" period, and determine if maternal and fetal characteristics can be used to differentiate individuals at low-risk of complications with more liberal oral intake.

This committee recommends patients who present in labor with a full stomach NOT be denied neuraxial anesthesia and/or analgesia. For all laboring patients, strategies should be implemented to reduce the need for general anesthesia in the event of emergency, particularly in patients who are not appropriately NPO. This includes shared decision-making surrounding establishing well-functioning neuraxial analgesia for utilization in the event that surgical anesthesia is required. Except for the case of patient request/refusal or medical contraindication, neuraxial anesthesia should be the technique of choice for parturients requiring surgical procedures.

Committee Recommendations:

• Solid food during active labor should be avoided; clear liquids, especially electrolyte containing beverages should be encouraged.
• Regardless of labor course, patients with high-risk medical and pregnancy conditions (see Table 1) may require stricter limitations on the amount and type of clear liquids consumed. 
• No recommendations can be made regarding the consumption of solid food during the pre-labor phase for a patient admitted for induction of labor. Shared decision making and informed consent on oral intake during the pre-labor time period are encouraged.
• Patients should NOT be denied neuraxial analgesia or anesthesia regardless of NPO status.

Table 1:

References:

1. Mendelson CL. The aspiration of stomach contents into the lungs during obstetric anesthesia. Am J of Obstet Gynecol 1946;52(2):191-205.
2. O’Sullivan G, Hari MS. Chapter 29 ‘Aspiration: Risk, Prophylaxis and Treatment’. In Chestnut’s Obstetric Anesthesia Principles and Practice, 5th edition. Saunders 2014: 665-683.
3. Catanzarite V, Willms D, Wong D, et. al. Acute respiratory distress syndrome in pregnancy and the puerperium: causes, courses and outcomes. Obstet Gynecol 2001;97:760-4.
4. Soreide E, Bjornestad E, Steen PA. Au audit of perioperative aspiration pneumonitis in gynaecological and obstetric patients. Acta Anaesthesiol Scand 1996;40:14-19.
5. Mhyre JM, Tsen LC, Einav S, et. al. Cardiac arrest during hospitalization for delivery in the United States, 1998-2011. Anesthesiology 2014;120:810-18.  
6. Cook T, Woodall N, Frerk C (Eds.) NAP4 Report and findings of the 4th National Audit Project of The Royal College of Anaesthetists. Major complications of airway management in the United Kingdom. March 2011.
7. Barboni E. Ultrasound evaluation of the stomach and gastric emptying in pregnant women at term: a case-control study. Minerva Anestesiol 2016;82(5):543-9.
8. Carp H, Jayaram A, Stoll M. Ultrasound examination of the stomach contents of parturients. Anesth Analg 1992;74:683-7. (duplicate)
9. Murphy DF, Nally B, Gardiner J, Unwin A. Effect of metoclopramide on gastric emptying before elective and emergent cesarean section. Br J Anaesth 1984;56:1113-6.
10. Roberts RB, Shirley MA. Reducing the risk of acid aspiration during cesarean section. Anesth Analg 1974;53:859-68.
11. Gin T, Cho AM, Lew JK, et al. Gastric emptying in the postpartum period. Anaesth Intensive Care 1991;19:521-4.
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14. Porter JS, Bonello E, Reynolds F. The influence of epidural administration of fentanyl infusion on gastric emptying in labour. Anaesthesia 1997;52:1151-6.
15. Ewah B, Yau K, King M, et al. Effect of epidural opioids on gastric emptying in labour. Int J Obstet Anesth 1993;2:125-8.
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17. Kelly MC, Carabine UA, Hill DA, Mirakhur RK. A comparison of the effect of intrathecal and extradural fentanyl on gastric emptying in laboring women. Anesth Analg 1997;85:834-8.
18. Van Thiel DH, Gavaler JS, Stremple J. Lower esophageal sphincter pressure in women using sequential oral contraceptives. Gastroenterology 1976;71:232-4.
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21. Reale SC, Bauer ME, Klumpner TT, Aziz MF, Fields KG, Hurwitz R, Saad M, Kheterpal S, Bateman BT: Frequency and Risk Factors for Difficult Intubation in Women Undergoing General Anesthesia for Cesarean Delivery: A Multicenter Retrospective Cohort Analysis. Anesthesiology 2022; doi: https://doi.org/10.1097/ALN.0000000000004173
22. Kluger MT, Short TG. Aspiration during anaesthesia: a review of 133 cases from the Australian Anaesthetic Incident Monitoring System (AIMS). Anaesthesia 1999;54:19-26.
23. Warner MA, Warner ME, Weber JG. Clinical significance of pulmonary aspiration during the perioperative period. Anesthesiology 1993;78:56-72.
24. Exarhos ND, Logan WD Jr, Abbott OA, Hatcher CR Jr. The importance of PH and volume in tracheobronchial aspiration. Dis Chest 1965;47:167-9.
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29. ACOG Committee Opinion #766. Committee on Obstetric Practice. Approaches to limit Intervention During Labor and Birth. Obstet Gynecol 2019;133(2):e164-73.
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34. Kubli M, Scrutton MJ, Seed PT, O’Sullivan G. An evaluation of isotonic ‘sport drinks’ during labor. Anesth Analg 2002;94:404-8.
35. Efrain Riveros-Perez et al. Ultrasound your NPO: Effect of body mass index on gastric volume in term pregnant women - Retrospective case series. Ann Med Surg (Lond) 2019;48:95-98.
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