Baby Talk: Do babies breathe in the womb before they are born?

April 10, 2012 

Babies lungs do not function the same way in the womb as they do outside of the womb.

Before birth a baby's lungs are filled with amniotic fluid. They do "practice" breathing towards the end of the pregnancy with periodic inhaling and exhaling of amniotic fluid.

Somewhere between the 24th and 28th week of the pregnancy, surfactant -- sometimes called "lung detergent" -- starts being produced in the amniotic fluid. As the pregnancy continues, more surfactant is produced. That is why the closer to term, 38 to 40 weeks, the better a baby is able to breathe outside the womb.

Surfactant coats the inside of the lungs and keeps the alveoli, or air sacs, open. Without enough surfactant the lungs collapse.

This can cause a condition called RDS, Respiratory Distress Syndrome. It is rare, but it can happen to a full term baby as well.

Other causes of RDS are infections, congenital conditions and meconium aspiration (when the baby breathes meconium, the first stool, into their lungs).

Research that led to the development of a commercially available surfactant to help these babies actually came from research done in the 1950s.

Dr. Richard Prattle in England discovered while working with nerve gases at a military laboratory that there was a substance that was necessary for the alveoli in the lungs to maintain effective lung expansion.

He speculated that if this substance could be produced in a lab and then administered to very young babies then maybe it could help treat RDS.

At the same time, John Clements, who was also studying the effects of nerve gas on lungs at the U.S. Army Chemical Center in Maryland, came to the same conclusion.

In 1980 an article in the medical journal Lancet, written by Tetsuro Fujwara, reported that he had had positive results in administering a synthetic surfactant to 10 babies born at 30 weeks.

The race was on to develop a surfactant to treat babies suffering from RDS. Just a few weeks ago, the FDA approved the fifth surfactant drug that can be used for this purpose in the United States.

The neonatologist, a doctor that specializes in taking care of sick babies, is the one who decides if a baby needs surfactant. It is administered through a special tube called an endotracheal tube. It is a tube that goes down the baby's throat into their lungs.

The development of synthetic surfactant over the last 25 years is considered by many as a major advance in the treatment of RDS. It gives those vulnerable babies a fighting chance to survive those first few critical weeks of life outside the womb.

Katie Powers, R.N., is a board-certified lactation consultant and perinatal educator at Manatee Memorial Hospital's Family BirthPlace. Her column appears every other week in Health. Contact her at

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