The common hospital policy of restricting oral intake during labor, often summarized by the Latin phrase nil per os (NPO), or “nothing by mouth,” frequently puzzles laboring individuals. This restriction is a medical precaution rooted in safety concerns regarding the potential need for emergency surgery. While this rule has been strictly enforced for decades, modern medical advancements have led to a significant reevaluation of the policy. Understanding the historical medical risks and the changes in anesthetic practices is necessary to explain why hospitals still exercise caution about what and when a person may eat during labor.
The Primary Historical Concern: Aspiration Risk
The strict “no eating” rule originated from a severe, potentially fatal complication known as Mendelson’s syndrome, or chemical pneumonitis, first described in 1946. This syndrome is caused by the accidental inhalation, or aspiration, of stomach contents into the lungs. Aspiration is dangerous because the highly acidic gastric fluid and undigested food particles cause a profound inflammatory reaction in the lung tissue.
Pregnancy and labor naturally increase this aspiration risk. Hormones like progesterone relax the esophageal sphincter muscle, which normally acts as a barrier to keep stomach contents down. Pressure from the enlarged uterus pushing on the stomach, combined with the pain and stress of labor, significantly slows gastric emptying. This means food stays in the stomach much longer than usual, creating a larger volume of contents available for aspiration.
The risk is magnified if the patient requires emergency general anesthesia. General anesthesia suppresses the body’s protective airway reflexes, such as coughing and gagging, allowing stomach contents to be inhaled into the lungs undetected. Before modern anesthetic techniques in the mid-20th century, general anesthesia was frequently used for both vaginal and cesarean deliveries. Mandatory fasting was therefore a life-saving measure to ensure the stomach was empty in case of an emergency.
Evolution of Policy: How Modern Anesthesia Changed Guidelines
The strict NPO policy has been significantly relaxed in many hospitals due to the widespread adoption of regional anesthesia, primarily epidurals and spinal blocks. Regional anesthesia numbs the lower body while allowing the patient to remain awake and conscious. Because the patient is conscious, their protective airway reflexes remain intact, dramatically reducing the risk of aspiration, even if an emergency procedure becomes necessary.
Current professional guidelines from major anesthesia and obstetrics organizations increasingly support light oral intake for low-risk laboring women. This shift acknowledges that the aspiration risk profile is much lower when regional anesthesia is the primary method of pain relief. If an urgent cesarean delivery is needed, the existing epidural or spinal catheter can often be used to provide surgical anesthesia, avoiding high-risk general anesthesia.
Allowing some oral intake also provides benefits by combating dehydration and fatigue associated with prolonged labor. Fasting can lead to accelerated starvation, and consuming carbohydrate or electrolyte-containing fluids helps maintain energy levels. The policy evolution balances maximizing patient comfort and energy during labor while minimizing the rare, but serious, risk associated with a sudden need for general anesthesia.
Practical Distinction: Clear Liquids Versus Solid Foods
Hospitals that have moved away from the strictest NPO rules almost universally distinguish between allowing clear liquids and restricting solid food intake. Clear liquids include water, ice chips, clear broths, fruit juices without pulp, and electrolyte-containing sports drinks. These liquids pass through the stomach very quickly, leaving minimal residue.
If a small amount of clear liquid were aspirated, the chemical damage is much less severe than with solid food. Solid foods, by contrast, take significantly longer to digest and empty from the stomach, a process already slowed by labor. Consuming solid food creates a large, high-volume reservoir of material, including particulate matter, in the stomach.
Should general anesthesia become necessary, aspirating particulate matter from solid food poses a much greater risk of causing a severe inflammatory reaction or airway obstruction than aspirating liquid. For this reason, solid food remains restricted during active labor for nearly all patients. The current standard is to allow moderate amounts of clear liquids for healthy, low-risk patients while avoiding all solid food to ensure the safest outcome if the delivery plan changes unexpectedly.