“There are several factors that percent a baby from inhaling water at the time of the birth. These inhibitory factors are normally present in all newborns. The baby in utero is oxygenated through the umbilical cord via the placenta, but practices for future air breathing by moving his intercostals muscles and diaphragm in a regular and rhythmic pattern from about 10 weeks gestation on. The lung fluids that are present are produced in the lungs and are similar chemically to gastric fluids. These fluids come out into the mouth and are normally swallowed by the fetus. There is very little inspiration of amniotic fluid in utero. 24-48 hours before the onset of spontaneous labor the fetus experiences a notable increase in the Prostaglandin E2 levels from the placenta which cause a slowing down or stopping of the fetal breathing movements (FBM). With the work of the musculature of the diaphragm and intercostals muscles suspended, there is more blood flow to vital organs, including the brain. You can see the decrease in FBM on a biophysical profile, as you normally see the fetus moving these muscles about forty percent of the time. When the baby is born and the Prostaglandin level is still high, the baby’s muscles for breathing simply don’t work, thus engaging the first inhibitory response.
A second inhibitory response is the fact that babies are born experiencing acute hypoxia or lack of oxygen. It is a built in response to the birth process. Hypoxia causes apnea and swallowing, not breathing or gasping. If the fetus were experiencing severe and prolonged lack of oxygen, it may then gasp as soon as it were born, possibly inhaling water into the lungs. If the baby were in trouble during the labor, there would be wide variabilities noted in the fetal heart rate usually resulting in the prolonged bradycardia, which would cause the practitioner to ask the mother to leave the bath prior to the babies birth.”

“One more factor that most people do not consider, but is vital to the whole waterbirth and aspiration issue is the fact that water is a hypotonic solution and lung fluids present in the fetus are hypertonic. So, even if water were to travel in past the larynx, they could not pass into the lungs based on the fact that hypertonic solutions are denser and prevent hypotonic solutions from merging or coming into their presence.

The last important inhibitory factor is the Dive Reflex and revolves around the larynx. The larynx is covered all over with chemoreceptors or taste buds. The larynx has five times as many taste buds as the whole surface of the tongue. So when a solution hits the back of the throat, passing into the larynx, the taste buds interprets what substance it is and the glottis automatically closes and the solution is then swallowed not inhaled. God built this autonomic relex into all newborns to assist with breastfeeding and it is present until about the age of 6-8 months when it mysteriously disappears.”