Have you ever wondered how babies get oxygen while they are in their mother’s womb?
After seeing a picture of a water birth, I started thinking—how is it possible for a baby to be born in water and not drown? While some people may already understand this, for others, it’s something they’ve never considered. The way babies receive oxygen before birth is a fascinating process.
Babies Don’t Actually Breathe in the Womb
Unlike fish, which use gills to extract oxygen from water, human babies do not breathe in amniotic fluid. Instead, they receive oxygen through the placenta, which connects to the umbilical cord. When a mother breathes in oxygen, it enters her bloodstream, passes through the placenta, and is delivered to the baby via the umbilical cord (Moore et al., 2020).
While the baby’s lungs begin developing around 9–11 weeks of gestation, they do not function in the same way as they will after birth. Instead of breathing air, babies practice “fetal breathing movements” (FBMs), which involve inhaling and exhaling small amounts of amniotic fluid. These movements help develop the lungs and prepare them for breathing after birth (Harding, 2001).
By 32 weeks gestation, these breathing-like movements become more coordinated, and by 37–39 weeks, the baby’s lungs are considered mature, meaning they can produce enough surfactant—a substance that prevents lung collapse—to support independent breathing (Jobe & Ikegami, 2000).
How Does a Baby Transition to Breathing Air?
When labor begins, contractions help push amniotic fluid out of the baby’s lungs. During delivery, the baby experiences a sudden change in environment—temperature, pressure, and exposure to air—which triggers their first breath.
Contrary to popular belief, a baby does not take its first breath when the umbilical cord is cut. Instead, breathing is initiated when the baby is exposed to air and the rise in carbon dioxide levels stimulates their brain to take a breath (Hillman et al., 2012).
Some key points about this transition:
- The baby remains connected to the umbilical cord even after birth, continuing to receive oxygen until they establish breathing.
- Delayed cord clamping (waiting at least 30–60 seconds to cut the cord) is recommended to allow extra oxygen-rich blood to transfer from the placenta to the baby, reducing the risk of anemia and other complications (Rabe et al., 2019).
- In water births, babies do not breathe underwater because they have a natural reflex (the “dive reflex”) that prevents them from inhaling until they feel air on their face (Johnson, 2018).
The Amazing Process of Birth
Once a baby takes its first breath, their lungs fully expand, and they no longer rely on the placenta for oxygen. This marks the final step in their transition to life outside the womb.
Understanding how babies receive oxygen before birth makes the idea of water births and fetal development even more fascinating. From the intricate exchange of oxygen through the placenta to the first breath that signals new life, the process is a remarkable example of human development.
Pretty interesting, isn’t it?!
References:
- Harding, R. (2001). “Fetal breathing movements.” The Journal of Physiology, 535(1), 1-15.
- Hillman, N. H., Kallapur, S. G., & Jobe, A. H. (2012). “Physiology of transition from intrauterine to extrauterine life.” Clinics in Perinatology, 39(4), 769-783.
- Jobe, A. H., & Ikegami, M. (2000). “Lung development and function after surfactant treatment.” Pediatrics, 106(6), 1293-1296.
- Johnson, P. (2018). “Water birth: The science behind the practice.” Midwifery Today, 126, 38-40.
- Moore, K. L., Persaud, T. V. N., & Torchia, M. G. (2020). The Developing Human: Clinically Oriented Embryology (11th ed.). Elsevier.
- Rabe, H., Gyte, G. M., Díaz-Rossello, J. L., & Duley, L. (2019). “Effect of timing of umbilical cord clamping and other strategies to influence placental transfusion at preterm birth on maternal and infant outcomes.” Cochrane Database of Systematic Reviews, 9(CD003248).
