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ISSN 1745-5111
Pediatric Health (2009) 3(3), 251–260 10.2217/PHE.09.24 © 2009 Future Medicine Ltd
Epidemiology
There are limited data regarding the epidemiol-
ogy of TTN; however, studies show that TTN
occurs in 3.6–5.7 per 1000 full-term infants [2,3] .
Despite being one of the most common causes
of neonatal respiratory distress [4,5] , many cases
may actually be underdiagnosed [6] . Retention
of fetal lung fluid may be more common in pre-
mature infants (up to 10 per 1000 births) but its
presence may be masked by coexisting problems
such as respiratory distress syndrome (RDS) [7] .
Several risk factors for TTN have been identi-
fied in the literature: birth by Cesarean section,
birth without labor, lower gestational age, male
sex, family history of asthma, (especially in the
mother [8]), macrosomia and maternal diabetes.
With the rising incidence of Cesarean sections
(CSs), as well as late preterm infant deliveries,
there is likely to be a rise in the incidence of
TTN as well.
Risk factors
Cesarean section
In the USA, the proportion of babies born by
CS has increased by 46% since 1996, reaching
a level of 31.1% of all births in 2006 [9] . In addi-
tion, there has also been a significant drop in the
number of women attempting vaginal birth after
a previous Cesarean delivery (VBAC) [10] . The CS
rate was approximately 20% in the UK in 2004,
while in Canada it was 22.5% between 2001
and 2002. The average CS rate is approximately
21.1% for the most developed nations in the
world, 14.3% for the less developed countries and
2% for the least developed countries [11] . A survey
of Latin American countries showed significant
The transition from intrauterine to extrauter-
ine environment during the process of birth is
accompanied by several changes that help the
newborn to adapt to the new environment. One
of the most important components of these
changes is the rapid clearance of fetal lung liq-
uid, which allows the establishment of venti-
lation and gas exchange through the lungs. If
lung fluid clearance is impaired, the infant may
present with clinical respiratory distress includ-
ing tachypnea, retractions and increased work of
breathing. Since many other conditions can have
similar symptoms in neonates, it is important
to understand the epidemiology, risk factors,
pathophysiology and management of transient
tachypnea of the newborn (TTN) to provide the
appropriate care for these babies.
Babies with TTN typically present with tachy-
pnea, retractions and grunting within a few hours
of birth, and occasionally have a requirement for
supplemental oxygen to maintain oxygenation.
The tachypnea is in the 80–100 breaths/min
range and frequently resolves by 12–24 h in most
cases, and by 48–72 h in more severe cases [1] , but
can persist longer. Most often, it is a diagnosis of
exclusion, as other diagnoses such as respiratory
distress syndrome (RDS) or pneumonia are ruled
out. A small subset of infants with TTN may
require very high O
2
concentrations (>60%) to
maintain their saturations, and may need further
respiratory support (intubation and mechanical
ventilation). Pulmonary hypertension with right-
to-left shunting across the ductus/foramen ovale
may be present as there may be an elevation in
the pulmonary vascular resistance associated with
retained fetal lung fluid.
Review
Risk factors and management of transient
tachypnea of the newborn
Lokesh Guglani
†
, Rita M Ryan & Satyan Lakshminrusimha
Transient tachypnea of the newborn (TTN) is the consequence of delayed clearance of fetal lung
liquid in the newborn. With recognition of the increased risk in babies born by Cesarean sections,
epidemiologic association with maternal asthma and increasing research on the possible role of
genetic polymorphisms of ion-channel subunits, our understanding of the pathophysiology of this
condition has vastly improved. We now know that the late-preterm infant, born at 34–36 weeks
gestation, is at increased risk for both TTN and respiratory distress syndrome due to surfactant
deficiency. As the incidence of Cesarean sections rises, there is likelihood of increased respiratory
morbidity in newborns that will necessitate additional medical interventions and exposure to
complications of intensive care. This review focuses on the risk factors that are associated with
the development of TTN and the treatment strategies that are employed for the management of
this condition.
†
Author for correspondence:
Division of Pediatric Pulmonology,
Children’s Hospital of Pittsburgh
Children’s Hospital Drive,
45th St and Penn Avenue,
Pittsburgh, PA 15201, USA
Tel.: +1 412 692 5630
Fax: +1 412 692 6645
lokesh.guglani@chp.edu
Keywords
asthma•cesareansection
•epithelialsodiumchannel•luid
transport•ionchannels•late
preterminfant•respiratory
distress•transienttachypneaof
newborn•typeIIpneumocytes
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