High serum antithyroid antibody values are
a risk factor for miscarriage
(March 2005)
The background of the study. Spontaneous miscarriage
is common. High serum antithyroid antibody concentrations, a marker
for autoimmune thyroid disease, may be a risk factor for miscarriage.
In this study, serum antithyroid antibodies and thyroid function
were measured in a large group of pregnant women, and they were
followed to determine the frequency of spontaneous miscarriage.
How the study was done. The study subjects were
534 women (mean age, 24 years) attending a prenatal clinic in Rio
de Janeiro who were 5 to 12 weeks pregnant. Serum antithyroid peroxidase
(TPO) antibodies, thyrotropin (TSH), and free thyroxine (T4) were
measured at the first visit, and the women were followed thereafter.
Miscarriage was defined as the spontaneous ending of pregnancy before
20 weeks.
The results of the study. Among the 534 women,
29 (5 percent) had a high serum anti-TPO antibody concentration.
Their serum TSH concentrations, but not serum free T4 concentrations,
were higher than the concentrations in the women with normal serum
antibody concentrations.
Thirteen women (2 percent) had a spontaneous miscarriage. The rate
was higher in older women and women with high serum anti-TPO antibody
or high serum TSH concentrations (Table).
| Table. Risk of Miscarriage as a Function of Age
and Serum Anti-TPO Antibody and TSH Concentrations. |
| |
Total |
Miscarriage (%) |
| |
|
|
| Age (yr) |
|
|
| <35 |
495 |
10 (2%) |
| ≥35 |
39 |
3 (8%) |
| High serum anti-TPO antibody |
|
|
| No |
505 |
10 (2%) |
| Yes |
29 |
3 (10%) |
| Serum TSH (mU/L) |
|
|
| <0.4 |
65 |
1 (2%) |
| 0.4–3.8 |
453 |
10 (2%) |
| >3.8 |
16 |
2 (12%) |
The conclusions of the study. The risk of spontaneous
miscarriage is increased in older women and in women with high serum
anti-TPO antibody and high serum TSH concentrations.
The original article. Sieiro Netto L, Medina Coeli
C, Micmacher E, Mamede Da Costa S, Nazar L, Galvao D, Buescu A,
Vaisman M. Influence of thyroid autoimmunity and maternal age on
the risk of miscarriage. Am J Reprod Immunol 2004;52:312-6.
|
