Decreased fetal movement in the third trimester can result from completely normal causes, like your baby’s sleep cycles or the position of your placenta, or from complications that need medical attention, like low amniotic fluid or problems with blood flow through the placenta. The key is knowing which patterns are expected and which ones warrant a call to your provider.
Fetal Sleep Cycles Are the Most Common Cause
By the third trimester, your baby cycles between periods of sleep and wakefulness, and during sleep phases, movement drops dramatically or stops altogether. These quiet stretches can last 20 to 40 minutes and occasionally up to 90 minutes. If you notice a lull in movement, it’s very likely your baby is simply sleeping. Research also shows a strong link between fetal activity and maternal wakefulness: your baby tends to be more active when you’re awake and may settle down when you do. This means you might miss movement during your own sleep, then perceive a quiet period when you wake up and start paying attention.
As pregnancy progresses into the final weeks, the type of movement also shifts. Your baby has less room to perform the dramatic kicks and rolls you felt at 24 or 28 weeks. Instead, movements may feel more like pushes, stretches, or squirming. This change in quality doesn’t necessarily mean your baby is moving less often. What matters most is whether you continue to feel a consistent pattern of movement throughout the day, even if the character of that movement has changed.
Placental Position and Body Type
An anterior placenta, one that attaches to the front wall of your uterus, acts as a cushion between your baby and your belly. This makes kicks and punches feel weaker and softer than they would with a placenta positioned along the back wall. People with anterior placentas often don’t feel their first kicks until after 20 weeks, compared to around 18 weeks for those with posterior placentas, and this muffling effect continues into the third trimester. You may find that you feel movement more clearly on the sides of your abdomen, where the placenta doesn’t block sensation.
Higher body mass index can have a similar dampening effect. More tissue between the uterus and the skin surface means subtler sensations, especially during quieter periods of fetal activity. Neither of these factors affects your baby’s actual movement. They only change how well you can feel it.
Low Amniotic Fluid
Low amniotic fluid, called oligohydramnios, physically restricts the space your baby has to move. But the problem often runs deeper than just limited room. In pregnancies where the baby is growing more slowly than expected, low fluid levels are closely tied to reduced blood flow through the placenta. The baby’s body redirects its blood supply toward the brain and heart and away from the kidneys, lungs, and digestive tract, which reduces urine output and, in turn, the volume of amniotic fluid. Research published in the journal Placenta found a direct, linear correlation between decreasing fluid levels and signs of poor oxygen delivery in these pregnancies.
This is one reason providers pay close attention when you report decreased movement. A drop in amniotic fluid can signal that the placenta isn’t delivering enough oxygen and nutrients, and reduced movement may be one of the earliest signs you’d notice at home.
Placental Insufficiency and Oxygen Supply
The placenta is your baby’s lifeline for oxygen and nutrition. When it doesn’t function well, whether from high blood pressure, preeclampsia, diabetes, or simply aging in a post-term pregnancy, the baby receives less of both. Babies respond to lower oxygen availability by conserving energy, which means fewer and less vigorous movements. This is sometimes called a “brain-sparing” response: the body prioritizes vital organs at the expense of everything else, including physical activity.
Placental problems tend to develop gradually, so the decrease in movement may also be gradual, making it harder to notice day to day. This is why tracking your baby’s movement pattern over time is more useful than comparing one day to another in isolation.
Umbilical Cord Problems
Cord compression, cord knots, or (rarely) damage to the umbilical vessels can cause sudden changes in fetal movement. When the cord is compressed, blood flow to the baby drops, and movement may decrease abruptly. A forensic case study published in Legal Medicine documented how physical forces on the umbilical cord led to vessel injury and fetal stillness in utero. While true cord accidents are uncommon, they tend to produce a more sudden and dramatic change in movement compared to the gradual decline seen with placental insufficiency. A baby who was very active and then becomes notably still is a situation that calls for prompt evaluation.
Medications and Substances
Certain medications taken during pregnancy can temporarily reduce fetal movement. Sedating drugs, including some anti-anxiety medications and strong pain relievers, cross the placenta and can make your baby less active for a period of time. Opioid pain medications are well-documented to reduce fetal movement, as are benzodiazepines. Alcohol has a similar sedating effect. If you’ve recently taken a new medication or had a change in dosage and notice less movement, mention both things to your provider so they can determine whether the medication is the likely explanation.
What To Do When Movement Feels Reduced
The standard approach is a focused kick count. Lie on your left side, minimize distractions, and pay attention to your baby’s movements for up to two hours. You’re looking for 10 distinct movements within that window. Movements include kicks, rolls, jabs, and stretches, but not hiccups. Most babies will reach 10 movements well before the two-hour mark. If you don’t feel 10 movements in two hours, contact your healthcare provider right away.
Your provider will typically start with a handheld Doppler to listen for the baby’s heartbeat. If the heartbeat is confirmed, the next step is usually a cardiotocography tracing (a monitor strapped to your belly that tracks heart rate patterns over 20 to 30 minutes). In some cases, your provider may order a biophysical profile, which uses ultrasound to evaluate five areas: fetal heart rate, breathing movements, body movements, muscle tone, and amniotic fluid volume. Each area is scored 0 or 2 points for a total of 10. A score of 8 or 10 is reassuring, while lower scores prompt further evaluation or closer monitoring.
One Norwegian model of care recommends that when a woman reports no fetal movements at all, monitoring with heart rate tracing and ultrasound should happen within two hours. The urgency scales with the severity of what you’re experiencing. A slight change in the character of movement is different from hours of complete stillness.
Patterns That Need Immediate Attention
Not every quiet period is an emergency, but certain situations call for prompt evaluation rather than waiting to see if things improve. Contact your provider or go to your hospital’s labor and delivery unit if you notice no movement at all for two or more hours despite doing a focused kick count, if there’s a sudden and dramatic change from your baby’s usual pattern, or if decreased movement accompanies other symptoms like vaginal bleeding, severe abdominal pain, or sudden swelling. A single episode of reduced movement that resolves with a kick count is common and usually benign. Repeated episodes of decreased movement over several days, even if each individual kick count eventually reaches 10, deserve medical attention because the pattern itself can indicate a developing problem.