Updated: Sep 26, 2019
Birth, Bath, and Beyond: The Science and Safety of Water Immersion During Labor and Birth
Barbara Harper, RN, CLD, CCE, CKC, DEM
From the Journal Of Perinatal Education
The fear of aspiration is a strong deterrent to water birth for some providers and a grave concern for pediatricians and parents alike.
When a baby is born, everyone awaits that first cry, which signals that the newborn has emerged safely from the womb. The delay of that response is very stressful for most people. Others view the newly born baby in the water opening his eyes and stretching his limbs in awe and see a baby who is doing exactly what he did for 9 months and still completely supported by placental circulation but now is in a larger, expanded womb—a womb with a view. The focus on the breath and that first cry has overshadowed all the other mechanisms that happen in the first moments that welcome us to life on planet Earth.
There are several mechanisms that prevent the baby from inhaling or gasping while it is still submerged in the water
as the head is born and after the full body has slipped into the water. An understanding of these mechanisms is important to appraise the safety of water birth. It is also important to have knowledge of the triggers for newborn breathing and what takes place in the cardiovascular system as the baby transitions from fetal circulation to newborn circulation. One of the most important triggers for breathing is the presence of gravity pushing equally on the face and stimulating the trigeminal nerve (the fifth cranial nerve) innervations around the nose and mouth.
Human beings need a gravitational force of 14.7 lbs/sq. in., as well as the presence of oxygen and carbon dioxide molecules, to trigger the switch from fetal circulation to newborn circulation. Once the shunts in the heart (the foremen ovale and ductus arteriosus) close and highly oxygenated blood flows into the pulmonary arteries, the well-vascularized tissue around the alveoli fill with blood, and the fluid that occupies every one of the alveolar spaces (air sacs) is resorbed into the thick erect capillaries (Johnson, 1996a). The thick viscous fluid that was present in the lungs during fetal life will now increase the blood volume by as much as 20% (Mercer & Skovgaard, 2002). Immediately after birth, the cardiac output to the lungs must increase from the 8% level in fetal life to a 45% level necessary for neonatal life and adult circulation. Therefore, some of the blood from the fetal “lung,” the placenta, is needed by the neonatal lungs for draining of the fetal lung fluids and adequate expansion and recruitment of lung tissue.
Immediate cord clamping eliminates the many benefits of placental transfusion and compromises lung expansion and function. The infant is left with only the blood that was in the body at the time of cord clamping, which is not adequate to create an increase in the circulatory bed at the same time that the infant’s organs (lung, liver, kidney, skin, gut, and brain) begin to assume the functions that had been sustained by the placenta during fetal life (Mercer, Vohr, Erickson-Owens, Padbury, & Oh, 2010).
In other words, the more blood that flows from the placenta into the newborn, the higher the blood volume. The more blood volume and the thicker the blood, the more fluids are able to leave the lung tissue. The many mechanisms that function to switch the newborn from fetal circulation to newborn status take place over the course of hours and sometimes days. Not all the fluids that were in the lungs prenatally are drawn out into the vascular circulation. The fluids that remain are drawn out of the lung tissue through the lymphatic system, which is stimulated over the following 72 hr by skin-to-skin placement, self-attachment, and breastfeeding.
One of the many benefits of water birth is immediate and uninterrupted skin-to-skin contact. Water-birth providers have learned so much from observing what normal full-term healthy newborns do in the habitat between the breasts. The neonate who is placed skin-to-skin regulates all his systems very quickly but is usually extremely quiet. The absence of vigorous crying is not indicative of the absence of newborn breathing. Quiet stable newborn breathing happens often without a single peep out of the baby who is immediately placed in the habitat (Moore, Anderson, & Bergman, 2007; Mori, Khanna, Pledge, & Nakayama, 2010). This is frequently observed of babies who are born in water. The presence of lung fluids in the alveolar spaces prenatally was explained by Dr. Paul Johnson, an Oxford University research physiologist, as one of several inhibitory factors that prevent the baby from gasping or taking a breath during the infant’s brief contact with the water during a water birth.
When he explained the mechanisms of newborn breathing at the First International Conference on Water Birth at Wembley Hall, London, in 1995, and said, “There are some things physiologically that are in favor of water birth,” there was a collective nod of understanding from more than 1,100 participants (Johnson, 1996b). With this information, along with the other 15 lectures, more water-birth practices were established all over the United Kingdom and Europe. Dr. Johnson went on to publish his explanations in the British Medical Journal in 1996 (Johnson, 1996a). There are several mechanisms that prevent the baby from inhaling or gasping while it is still submerged in the water. Two other inhibitory factors need to be examined. The first one involves fetal breathing movements, which take place 40% of the time in utero, from 10 weeks’ gestation.
At 24–48 hr before the onset of normal labor, the prostaglandin E2 levels rise in both mother and fetus.
The mother’s cervix softens, but the fetus slows the rate of active fetal breathing in an effort to conserve oxygen.
After 4 cm of dilation, it is thought that the prostaglandin levels are much higher, preventing any fetal breathing movement from taking place from that point forward throughout the labor and birth process. It makes sense to think that an expansion of the intercostal muscles during the birth is not something that would aid in the expulsion of the fetus from the birth canal. Dr. Johnson explained further that if the muscles are inhibited from working, the fetus or newborn has no ability to gasp or inhale. The musculature that operates the lungs simply is offline during the birth—they are not functional. A prominent theme in Dr. Johnson’s work is the explanation of normal newborn mild hypoxia and how it prevents the neonate from taking a breath by causing a swallowing reflex.
All newborns are born with mild hypoxia. It is expected. The mild hypoxia causes bradycardia, apnea (absence of breathing), and swallowing. The very first accomplishment on the long list of transitional activities for a newborn is to swallow the contents of the mouth. Presumably, the mouth is full of vaginal secretions, amniotic fluid, and other bacteria-laden secretions, which need to get into the gut to begin to colonize and prime the new digestive system with the right bacterial probiotics. Swallowing those fluids and clearing his or her own airway takes place before the first breath. Experienced providers of undisturbed birth, including water birth, often report that newborns will swallow then spit, cough, and perhaps sneeze before regular respirations are noticeable.
When a baby’s mouth is suctioned with either a bulb syringe or a DeLee trap, this act interferes with the mechanisms to introduce normal flora into the gut. Rather than enhancing the ability for the newborn to breathe, it may in fact disrupt breathing efforts (Carrasco, Martell, & Esto, 1997). The thermal regulation abilities of the newborn are enhanced by delayed cord clamping, which will allow all the skin capillaries to fill, and improved by skin-to-skin contact. Johnson’s review of respiratory physiology suggests that in a nonstressed fetus, it is unlikely that breathing will commence in the short time that the baby’s head is underwater (Johnson, 1996a). Johnson sees no reason to prevent this option being offered to birthing people.