Vomiting can happen during labor, but it’s not a reliable sign that labor is starting. Nausea and vomiting occur most commonly during the transition phase of active labor, when the cervix is dilating from about 7 to 10 centimeters. If you’re experiencing nausea before contractions begin, it could signal that labor is approaching, but it could just as easily be caused by something else entirely.
Nausea Before Labor Starts
Some women notice nausea, loose stools, or a general “off” feeling in the hours or days before labor begins. This is thought to be the body’s response to shifting hormone levels, particularly the rise in prostaglandins that help soften the cervix. But nausea on its own is a poor predictor of labor. It can be caused by late-pregnancy heartburn, something you ate, anxiety, or dozens of other things. Unless nausea comes alongside other early labor signs like regular contractions, lower back pain, or your water breaking, there’s no reason to assume it means labor is imminent.
When Vomiting Typically Happens During Labor
The most common time for vomiting during labor is the transition phase, the intense final stretch of the first stage when contractions are close together and the cervix finishes dilating. The physical intensity of transition, combined with hormonal shifts and pressure on the stomach, can trigger nausea or vomiting even in women who felt fine earlier. Some women vomit while actively pushing during the second stage of labor as well.
That said, vomiting during labor is less common than many people expect. Research on low-risk mothers found that over 80% of women who ate or drank during labor had no vomiting at all. Among the roughly 20% who did vomit, about 40% vomited more than once. So while it’s normal and nothing to worry about, most women get through labor without it.
Pain Medications Can Cause Nausea Too
If you vomit during labor after receiving pain relief, the medication itself may be the cause rather than the labor process. Opioid pain medications used during labor list nausea, vomiting, and drowsiness as common side effects, with higher doses carrying a greater risk. Nitrous oxide (sometimes called laughing gas) can also cause nausea, vomiting, or dizziness. If your nausea started shortly after receiving pain relief, let your care team know so they can adjust your treatment.
Epidurals are less likely to cause vomiting directly, though the drop in blood pressure that sometimes follows an epidural can trigger nausea.
Staying Comfortable If You’re Vomiting
Vomiting during labor is unpleasant but usually short-lived, especially if it happens during transition, which is the shortest phase of labor. A few things can help. Sucking on ice chips or rinsing your mouth with water keeps your mouth from feeling dry and clears the taste. Some hospitals and birth centers offer aromatherapy with essential oils like peppermint or lavender, which can ease nausea. Your doctor or midwife may also offer anti-nausea medication depending on how far along you are.
If vomiting is persistent, the main concern is dehydration. Your care team will monitor your fluid intake and can provide IV fluids if needed. This is routine and not a sign that anything is going wrong.
When Vomiting Signals Something More Serious
In most cases, vomiting during late pregnancy or labor is harmless. But certain patterns deserve prompt attention because they can indicate conditions that affect the liver or blood pressure.
Preeclampsia and a related condition called HELLP syndrome can cause nausea and vomiting alongside other symptoms. About 50% of women with HELLP syndrome experience nausea or vomiting, often accompanied by pain in the upper right side of the abdomen (below the ribs), sudden swelling, headaches, or visual changes like blurred vision or seeing spots. These symptoms can develop before or during labor.
A rarer but serious condition called acute fatty liver of pregnancy causes nausea and vomiting in about 70% of affected women, along with fatigue, upper abdominal pain, and yellowing of the skin or eyes. This condition typically appears in the third trimester and requires immediate medical care.
The key differences to watch for: normal labor-related vomiting comes with contractions and tends to happen during the most intense phases. Vomiting paired with persistent upper abdominal pain, severe headache, vision changes, or yellowing skin points to something that needs evaluation right away, regardless of whether you’re in labor.
Nausea vs. Other Early Labor Signs
If you’re trying to figure out whether labor is starting, nausea alone won’t tell you much. More reliable early labor signs include contractions that come at regular intervals and gradually get closer together, a persistent dull ache in your lower back, the loss of your mucus plug (sometimes tinged with blood), and your water breaking. Many women also notice a burst of energy or “nesting instinct” in the day or two before labor begins.
Nausea becomes a more meaningful signal when it shows up alongside these other signs. If you’re having regular contractions and start feeling nauseated, it may indicate you’re progressing into active labor or transition. On its own, though, nausea in late pregnancy is too common and too nonspecific to count on as a labor indicator.