Feeling movement within the womb is a profound part of late pregnancy. As the 36-week mark approaches, the baby has grown significantly, occupying most of the available space. This changes the nature of the sensations an expectant parent feels. Many movements felt are practice routines as the baby prepares for life outside the uterus. Understanding the different types of activity can help interpret these unique sensations.
The Reality of Fetal Respiration
The simple answer to whether a baby can breathe in the womb is no, not in the way breathing is understood outside the body. The fetus is suspended in amniotic fluid, which makes inhaling air impossible. The baby’s lungs are not used for oxygen exchange until after birth, remaining largely collapsed and filled with fluid throughout gestation.
Instead, the baby relies completely on the maternal-fetal circulatory system for oxygen supply. Oxygen-rich blood flows from the parent through the umbilical cord to the fetus. The placenta acts as the temporary respiratory organ, transferring oxygen from the parent’s bloodstream into the fetal blood and removing carbon dioxide waste.
Fetal Breathing Movements: The Practice Runs
Although the lungs are not used for gas exchange, the fetus engages in actions known as Fetal Breathing Movements (FBMs). These movements are rhythmic contractions of the diaphragm and chest wall muscles that mimic postnatal breathing mechanics. FBMs typically begin early in gestation but become more consistent and pronounced in the third trimester.
The purpose of these practice runs is to condition the muscles and stimulate lung development necessary for life after delivery. During an FBM, the baby draws small amounts of amniotic fluid into the lungs, which helps expand the airways and promote the maturation of lung tissue. By 36 weeks, these movements may occur up to 30 to 40 percent of the baby’s active time. These movements are usually too subtle for the parent to detect reliably.
Distinguishing Movements: Hiccups, Kicks, and Practice Breathing
The sensations felt by the expectant parent at 36 weeks are usually a combination of three distinct types of movement. True Fetal Breathing Movements are rapid, shallow motions of the chest wall that are rarely felt by the parent. They may register only as a very slight, fleeting flutter or twitch, lacking the sustained force or rhythm of other sensations.
Fetal hiccups, which are a different type of diaphragmatic spasm, are often mistaken for breathing. Hiccups feel highly rhythmic, continuous, and pulsating, much like a steady internal drumbeat that repeats for several minutes. They are caused by the diaphragm contracting suddenly as the baby “inhales” amniotic fluid, and the sensation is often localized to one specific area of the abdomen.
General movements, such as kicks, rolls, and stretches, are the strongest and least rhythmic sensations. These are the isolated jabs and sustained pressures felt as the baby changes position or flexes a limb. At 36 weeks, limited room means these movements feel more like powerful pushes or sustained rolls against the uterine wall, rather than the sharp kicks felt earlier in the pregnancy.
Monitoring Fetal Activity at 36 Weeks
Monitoring the baby’s overall activity remains an important practice in late pregnancy. Fetal movement counting, sometimes called kick counting, is a simple way for parents to track their baby’s well-being in the third trimester. This involves noting the time it takes to feel a certain number of movements, such as 10 distinct movements.
When counting, it is important to include only strong, generalized movements like kicks, rolls, and jabs, and to exclude the rhythmic sensations of hiccups. Parents should establish a baseline for what constitutes normal movement, as every fetus has a unique pattern of activity. A sudden decrease or a significant change in the established pattern of movement signals the need to contact a healthcare provider immediately for further evaluation.