Studying Fetal Breathing Patterns

The aerodigestive tract is a complex system of integrated anatomical structures supporting
ingestive and respiratory functions. The developmental origins of this system begin in utero
where the prenatal growth of morphologic structures and their associated emerging behaviors
form key physiologic foundations necessary to sustain life at birth. The quality of
aerodigestive development is thus inextricably related to both the structural integrity of
its growing anatomy and the emergence of processes that promote aerodigestive functioning.
Our past research (NIH CC-00-99; NNMC #B99-089) focused specifically on emerging
oropharyngeal, and laryngeal movements of neonatal swallowing and phonation. Through
innovative sonographic techniques, this work documented ingestive development in the living
fetus; however, respiratory aspects were not explored. Intuitively, disruptions to the
fetal-maternal environment also influence respiratory development and, thus an arrest,
disorder, or delay in maturation of upper airway mechanisms may directly affect subsequent
postnatal respiratory function. Thus, the purposes of this protocol are to: 1) continue
exploration of human fetal development by elucidating the association between upper airway
growth and emerging prenatal respiratory function and, 2) determine identifiable patterns of
normal respiratory maturation that may provide indicators of postnatal airway performance.

This initiative is based on the premise that amniotic fluid volumes are influenced by the
integrity of upper airway mechanisms and thus are important for aerodigestive-related
development and fetal well being. In a collaborative effort with National Naval Medical
Center, this project will use a novel standardized 4-axis sonographic examination to
quantify growth and respiratory-related fluid flow mechanics in the upper airway of the
living human fetus. The use of this noninvasive ultrasound technique as part of the clinical
prenatal examination will not only discriminate function at four upper airway sites
(perinasal, oral, pharyngeal, and tracheal), but provide estimates of amniotic fluid flow
volumes, inspiratory-expiratory fluid flow velocities and durations, and Doppler waveform
patterns associated with fetal breathing and ingestive processes. This provides a method
from which we can begin to explore how deviations in amniotic fluid regulation may be
associated with morbidity and mortality and, the predictive utility of these indices in
understanding conditions such as oligohydramnios or polyhydramnios. This germinal database
will include healthy fetuses 16.0 to 39.6 weeks' gestational age and cases with
polyhydramnios/oligohydramnios. By elucidating how developing structures integrate with
emerging upper respiratory behaviors, this work will document the maturational events
underlying normal function at birth that in turn may facilitate future clinical strategies
for successful postnatal care.

- INCLUSION CRITERIA:

Both normal controls and test cases will be openly recruited from referrals to the NNMC
PAC.

Healthy mother's 18 years of age and over with uneventful, singleton pregnancies dated at
16.0 to 39.6 weeks gestation (based on last menstrual period) are the inclusion criteria.

EXCLUSION CRITERIA:

Mothers with pregnancies outside this dating and under 18 years of age are an exclusion
factor.