A contraction is a tightening of the uterine muscle that you can feel as your belly hardens, often accompanied by cramping or pain. Contractions serve different purposes at different stages of pregnancy: some are your body’s way of practicing, others signal that labor is starting, and a final round after delivery helps your uterus return to its original size. Understanding which type you’re experiencing, and when to take them seriously, is one of the most practical things you can learn before your due date.
How Contractions Work
Your uterus is mostly muscle. When the hormone oxytocin binds to receptors on those muscle cells, it triggers them to tighten and then release. As your due date approaches, rising estrogen levels make those receptors more sensitive to oxytocin, which is why contractions become stronger and more frequent toward the end of pregnancy. Oxytocin also stimulates the release of other hormones called prostaglandins, which soften and thin your cervix so it can eventually open wide enough for your baby to pass through.
Braxton Hicks Contractions
Braxton Hicks contractions are often called “practice contractions.” They can start as early as the second trimester, though most people notice them in the third. They feel like a tightening or hardening across the front of your belly, and they show up at random intervals with no predictable pattern. They’re usually painless, though some feel similar to mild menstrual cramps.
The key difference from real labor: Braxton Hicks contractions don’t get stronger, don’t come closer together over time, and don’t cause pain in your lower back or hips. They also tend to ease up if you change positions, drink water, or rest. If lying down or walking around makes the tightening stop, that’s a strong sign it’s Braxton Hicks.
Prodromal Labor
Prodromal labor falls in a frustrating middle ground. These contractions can be mildly painful, come as frequently as every five minutes, and last up to a minute each. That pattern can look a lot like early labor, which is why prodromal labor sends many people to the hospital only to be told they’re not yet dilating.
The distinguishing feature is that prodromal labor never advances beyond its starting point. The contractions don’t get stronger or closer together, and they don’t cause your cervix to open. There’s no evidence that prodromal labor speeds up your eventual labor or helps your cervix thin out faster. The only reliable way to tell the difference is a cervical check by your provider. If you’re not dilating, it’s almost certainly prodromal labor, and it will resolve on its own before true labor begins.
What True Labor Contractions Feel Like
True labor contractions feel different from every other type. The pain typically starts in your lower back and wraps around to the front of your belly, or you feel it deep in your hips and pelvis. Unlike Braxton Hicks, changing positions or resting won’t make them go away. They build in intensity, peak, and then gradually ease before the next one begins.
Most people describe early labor contractions as strong period cramps. As labor progresses, the sensation becomes more intense and harder to talk or move through. The pain has a wave-like quality, rising and falling over 30 to 90 seconds depending on the stage of labor.
Contraction Patterns Through Labor
Labor unfolds in stages, and your contraction pattern changes with each one.
During early labor, your cervix opens to about 6 centimeters. Contractions are milder, shorter, and spaced further apart. This phase typically lasts 6 to 12 hours, and many people spend it comfortably at home. As labor becomes active, contractions settle into a steady rhythm, coming every 3 to 5 minutes and lasting 45 to 60 seconds or longer. Active labor, which takes your cervix from 6 to 10 centimeters, usually lasts 4 to 8 hours. During the pushing stage, contractions come every 2 to 5 minutes and last 60 to 90 seconds each.
The general guideline for when to head to the hospital: if this is your first baby, go when contractions come every 3 to 5 minutes and last at least 45 to 60 seconds over the course of an hour. If you’ve given birth before, the threshold is a bit wider, since labor often moves faster the second time. Contractions every 5 to 7 minutes, lasting 45 to 60 seconds, are the signal to go in.
How to Time Contractions
Timing contractions is straightforward. Start a timer when one contraction begins and note when it ends. That’s the duration. Then note when the next contraction starts. The gap between the start of one contraction and the start of the next is the frequency. Most people use a phone app, though a clock with a second hand works just as well.
What you’re looking for is a pattern. True labor contractions will gradually get longer, stronger, and closer together. If the intervals stay random or the intensity doesn’t change over an hour or two of tracking, you’re likely dealing with Braxton Hicks or prodromal labor.
Contractions Before 37 Weeks
Occasional tightening before 37 weeks is normal. What isn’t normal is having six or more contractions in a single hour, especially if they come with other symptoms like fluid or blood leaking from your vagina, pelvic pressure, or low back pain that doesn’t let up. Six or more contractions per hour before 37 weeks is the threshold that signals possible preterm labor, and it warrants a call to your provider right away.
Postpartum Contractions
Contractions don’t end with delivery. In the first 12 hours after birth, your uterus contracts regularly and strongly. These “afterpains” serve two critical purposes: they reduce blood flow to the spot where your placenta was attached, preventing excessive bleeding, and they help your uterus shrink back toward its pre-pregnancy size.
Afterpains feel like intense cramping that lasts about five minutes before gradually easing. They’re typically noticeable for a few days after birth and tend to be more intense with second or subsequent pregnancies. Breastfeeding can trigger them because nursing releases oxytocin, the same hormone that drives labor contractions.
Warning Signs During Contractions
Most contractions, even uncomfortable ones, are a normal part of pregnancy and labor. But certain symptoms alongside contractions need immediate medical attention:
- Vaginal bleeding that’s heavier than spotting, similar to a period
- Fluid leaking from your vagina, especially if it smells unusual
- Severe belly pain that is sharp, sudden, or keeps getting worse rather than coming in waves
- A change in your baby’s movement, particularly if your baby seems to be moving much less than usual or has stopped moving
There’s no specific number of fetal movements considered universally “normal.” What matters is a noticeable change from your baby’s typical pattern. If something feels off, trust that instinct.