Risk factors for congenital hypothyroidism: results of a population case-control study (1997-2003).
OBJECTIVE
To identify risk factors for permanent and transient congenital hypothyroidism (CH).


METHODS
A population-based case-control study was carried out by using the network created in Italy for the National Register of Infants with CH.


METHODS
Four controls were enrolled for each new CH infant; 173 cases and 690 controls were enrolled in 4 years. In order to distinguish among risk factors for permanent and transient CH, diagnosis was re-evaluated 3 years after enrollment when there was a suspicion of transient CH being present. Familial, maternal, neonatal and environmental influences were investigated.


RESULTS
An increased risk for permanent CH was detected in twins by a multivariate analysis (odds ratio (OR) = 12.2, 95% confidence interval (CI): 2.4-62.3). A statistically significant association with additional birth defects, female gender and gestational age >40 weeks was also confirmed. Although not significant, an increased risk of CH was observed among infants with a family history of thyroid diseases among parents (OR = 1.9, 95% CI: 0.7-5.2). Maternal diabetes was also found to be slightly associated with permanent CH (OR = 15.7, 95% CI: 0.9-523) in infants who were large for gestational age. With regard to transient CH, intrauterine growth retardation and preterm delivery were independent risk factors for this form of CH.


CONCLUSIONS
This study showed that many risk factors contribute to the aetiology of CH. In particular, our results suggested a multifactorial origin of CH in which genetic and environmental factors play a role in the development of the disease.
Medda
Emanuela
E
Centro Nazionale di Epidemiologia, Sorveglianza e Promozione della Salute, Istituto Superiore di Sanità, Rome, Italy.
Olivieri
Antonella
A
Stazi
Maria Antonietta
MA
Grandolfo
Michele E
ME
Fazzini
Cristina
C
Baserga
Mariangiola
M
Burroni
Massimo
M
Cacciari
Emanuele
E
Calaciura
Francesca
F
Cassio
Alessandra
A
Chiovato
Luca
L
Costa
Pietro
P
Leonardi
Daniela
D
Martucci
Maria
M
Moschini
Lidia
L
Pagliardini
Severo
S
Parlato
Giuseppe
G
Pignero
Alberto
A
Pinchera
Aldo
A
Sala
Danielle
D
Sava
Lidia
L
Stoppioni
Vera
V
Tancredi
Francesco
F
Valentini
Fabiola
F
Vigneri
Riccardo
R
Sorcini
Mariella
M
D000328:Adult; D016022:Case-Control Studies; D002675:Child, Preschool; D003409:Congenital Hypothyroidism / Q000209:etiology*; D004200:Diseases in Twins; D004777:Environment; D005260:Female; D005317:Fetal Growth Retardation; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007455:Iodine / Q000172:deficiency; D008297:Male; D008423:Maternal Age; D011247:Pregnancy; D011254:Pregnancy in Diabetics; D012307:Risk Factors
D007455:Iodine