Influence of thyroid autoimmunity and maternal age on the risk of miscarriage.
OBJECTIVE
Recently, studies have shown an association between antiperoxidase for the detection of thyroid autoimmunity (TAI) and abortion. Another point to be considered is the association of high risk of abortion and maternal age. The aim of the present study was to evaluate if the association between TAI and miscarriage could also be verified whether a population of unselected pregnant young women who normally present a low risk of miscarriage.


METHODS
We studied 534 pregnant women, by determining their serum thyroid antiperoxidase antibodies (TPO-Abs), thyrotropin (TSH) and free thyroxine (fT4) levels. Our end point was the pregnancy loss or live birth.


RESULTS
Age ranged from 12 to 49 years (mean +/- S.D.; 23.5 +/- 5.9). Of 534 women, 29 (5.4%) were TPO-Ab positive. TSH levels were significantly higher in TPO-Ab-positive women compared with TPO-Ab negative women (median; 1.9 versus 1.1; P = 0.001). Elevated TSH levels were found in 13.8% (4 of 29) of the TPO-Ab-positive women compared with only 2.4% (12 of 505) in the TPO-Ab-negative women. There were no significant differences in fT4 levels in relation with autoimmunity and risk of miscarriage. The overall risk of miscarriage was 2.4% (13 of 534). Risk of miscarriage was significantly higher among women older than 35 years (7.7%), TPO-Ab positive (10.3%) and presenting high levels of TSH (12.5%). These factors remained independently associated with the risk of miscarriage in full multivariate analysis.


CONCLUSIONS
We conclude that TAI is independently associated with is a higher risk of miscarriage in a population of unselected pregnant presenting a low risk of miscarriage.
Sieiro Netto
Lino
L
Faculdade de Medicina/Serviços de Endocrinologia, HUCFF, UFRJ, Rio de Janeiro, Brazil. sieirorj@bol.com.br
Medina Coeli
Claudia
C
Micmacher
Eduardo
E
Mamede Da Costa
Sheila
S
Nazar
Luiz
L
Galvão
Daut
D
Buescu
Alexandru
A
Vaisman
Mario
M
D000022:Abortion, Spontaneous / Q000097:blood / Q000453:epidemiology / Q000209:etiology*; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001323:Autoantibodies / Q000097:blood*; D001327:Autoimmune Diseases / Q000150:complications / Q000175:diagnosis; D015551:Autoimmunity; D001938:Brazil / Q000453:epidemiology; D002648:Child; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008423:Maternal Age; D008875:Middle Aged; D009195:Peroxidase / Q000276:immunology; D011247:Pregnancy; D012307:Risk Factors; D013959:Thyroid Diseases / Q000097:blood / Q000150:complications / Q000276:immunology; D013961:Thyroid Gland / Q000201:enzymology / Q000276:immunology*; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood
D001323:Autoantibodies; D013972:Thyrotropin; D009195:Peroxidase; D013974:Thyroxine