Thyroid autoimmunity in pregnant Nigerians

Thyroid autoimmunity is a recognized disorder in pregnancy and is associated with a number of adverse pregnancy outcomes.

This study set out to determine the relationship between pregnancy and thyroid autoimmunity in Nigerian women.

This was an analytical cross-sectional study carried out in a tertiary hospital in South Western Nigeria with a total study population of 108 pregnant and 52 nonpregnant women.

Serum thyroid stimulating hormone, free thyroxine and thyroid peroxidase antibodies (TPO-Ab) were quantitatively determined using enzyme linked immuno-assays. Pregnant women were grouped into three categories (<14 weeks, 14-28 weeks and > 28 weeks). The relationship between pregnancy and thyroid autoimmunity was determined using Spearman correlation. Analysis of variance was used in comparison of means, Chi-square test used in analyzing proportions while P ≤ 0.05 was considered as significant.

The mean age of the pregnant women was 30.4 ± 6.0 years while the mean gestational age of all pregnant women was 20.6 ± 9.6 weeks. The mean TPO-Ab of 11.58 IU/ml in the pregnant was significantly higher than that of the controls of 7.23 IU/ml (P < 0.001). Out of 108 pregnant women, 27 (25%) had elevated TPO-Ab as against about 2% of the nonpregnant women levels P < 0.001. The number of pregnant women with elevated TPO-Ab levels decreased from 33.3% in the first group to 25.6% and 15.2% in the second and third groups.

Thyroid autoimmunity expressed by the presence of TPO-Ab is high among pregnant Nigerian women and the frequency of autoimmunity appears to decline with advancing gestational age.