Choanal atresia is a well-defined congenital malformation; however, little is known about its prevalence and risk factors. Data from the Iowa Registry for Congenital and Inherited Disorders were used to examine prevalence, infant, and maternal characteristics of choanal artesia. Data from the National Birth Defects Prevention Study (NBDPS) were used to examine selected risk factors for choanal atresia. Overall prevalence was estimated as number of choanal atresia cases per 10,000 live births with 95% confidence intervals (CI)s. Crude and adjusted odds ratios (OR)s and 95% CIs were estimated to investigate selected risk factors. The overall prevalence of choanal atresia among live born deliveries in Iowa from January, 1998 through December, 2005 was 0.46 (95% CI=0.27, 0.78) per 10,000 live births. Using data from the NBDPS, choanal atresia cases were compared to unaffected control infants for births from October 1997 through December 2005. Overall, case infants compared to control infants were more likely to be female, preterm, and a multiple birth. For all choanal atresia cases combined, odds of high maternal zinc (OR=2.1; 95% CI=1.2, 3.9) and vitamin B-12 (OR=2.4; 95% CI=1.4, 4.3) intake in the year prior to pregnancy, and maternal periconceptional (one month before through three months after conception) exposure to anti-infective urinary tract medications (OR=3.3; 95% CI=1.3, 8.4) were significantly elevated among case compared to control mothers. For isolated choanal atresia cases (those with no additional major malformations), odds of maternal periconceptional exposure to passive cigarette smoke (OR=2.3; 95% CI=1.0, 5.3) as well as maternal intake of 3 or more cups of coffee per day one-year prior to pregnancy were increased (OR=2.9; 95% CI=1.3, 6.4) for case compared to control mothers. The reverse was found for low maternal intake of pantothenic acid (OR=0.4; 95% CI=0.2,0.9) and vitamin A (OR=0.3; 95% CI=0.1, 0.8) one-year prior to pregnancy. The current study provided support for potential associations between maternal health behaviors before and during pregnancy and choanal atresia; however, the findings were based on a modest number of cases. The study needs to be replicated in a larger case sample, also examining the role of genetics in choanal atresia.

La ventilation nasale est vitale pour le nouveau-né, respirateur nasal exclusif. Le tiers antérieur des fosses nasales peut être modifié par une sténose congénitale de l’orifice piriforme, tandis leur partie postérieure peut être fermée par une atrésie choanale uni ou bilatérale ou par des lésions du nasopharynx.Les simulations numériques permettent d’analyser l’écoulement et le conditionnement de l’air en contournant les limites techniques et éthiques rencontrées in vivo. Devant la rareté des données dans la littérature, une étude de faisabilité a été nécessaire et concluante : les modèles numériques sont qualitativement proches de la réalité. Un travail sur les conditions physiologiques chez le nouveau-né a ensuite été réalisé, avec une méthodologie retravaillée. La reconstruction tridimensionnelle des fosses nasales est possible dès la naissance. La création d’une sphère centrée sur la pointe du nez, éloignant le domaine d’entrée de la zone d’intérêt, a permis d’analyser le rôle du tiers antérieur des fosses nasales.La valve nasale joue un rôle majeur en inspiration : perte de charge, accélération, guidage des flux et réchauffement de l’air. Les trois quarts du réchauffement ont lieu en amont du cornet inférieur. Une obstruction nasale entraîne une réduction des vitesses et une augmentation des températures de l'air. La simulation de l’inspiration d’air à 0°C a permis de constater que les fosses nasales permettent d’amortir les effets du refroidissement de l’air extérieur.Ce travail constitue une première approche de la physiologie de la ventilation nasale du nouveau-né par modélisation numérique, indispensable à la compréhension de la pathologie nasale néonatale. / Nasal breathing is essential for the newborn, exclusive nasal breather. The anterior third of the nasal fossae may be modified by a congenital stenosis of the pyriform aperture, while their posterior part may be closed by unilateral or bilateral choanal atresia.Numerical simulations are a good means to analyze airflow and air-conditioning: they circumvent the technical and ethical limits encountered in vivo. Given the rarity of available data in the literature, a feasibility study was necessary and was conclusive: numerical models are qualitatively close to reality. A work on the physiological conditions in newborns was conducted, using refined methodology. The three-dimensional reconstruction of the nasal fossae is possible from birth. The creation of a sphere centered on the tip of the nose, moving the boundary conditions away from the area of interest, made it possible to analyze the role of the anterior third od the nasal fossae.The nasal valve plays a major in inspiration: it is a zone of pressure loss, acceleration, flow guidance and air warming. Three-fourths of the warming takes place upstream the inferior turbinate. A partial nasal obstruction modifies these results with lower velocities and higher temperature of the air. The simulation of the inspiration of cold air (0°C) has shown that the nasal fossae can dampen, without canceling, the effects of air cooling. This work is a first approach to the physiology of nasal ventilation of the newborn by numerical modeling, which is essential to the understanding of neonatal nasal pathology.