Maternal Thyroid Hormones Levels in Normal Sudanese Pregnant Women

Abstract

A prospective study was conducted during the period 2001 to 2003 at Omdurman maternity, Khartoum teaching and Khartoum North teaching hospitals. One hundred and twenty Sudanese pregnant women at different stages of pregnancy were chosen for this study. Forty non-pregnant women of the same age without endocrine disease were chosen as control. Thyroid hormones total (T4 and T3) and free (FT4 and FT3) were measured. In addition TSH, hCG and TG were also measured in both groups. The Study group were divided according to the gestational age (weeks) into three subgroups: - First trimester 5 – 12 weeks, second trimester 13 – 27 weeks and third trimester 28 – 40 weeks. Determination of serum hormones concentration was carried out using a highly sensitive specific RIA technique. The results of this study showed that there was an increase in concentration of total thyroid hormones (T4 and T3), but the increase did not proceed at steady level during the different trimesters both hormones increase significantly in all trimesters compared with control group and continued thereafter, but at slower rate. Mean serum free T4 increase significantly during the first trimester, while the increase in T3 concentration was not significantly different compared to non-pregnant women. Free T4 and free T3 decreased significantly during second and third trimesters of pregnancy compared with non- pregnant women. Thyroid stimulating hormones (TSH) level remained within the normal range throughout pregnancy period although pregnant women had suppressed Below normal range in the first trimester( 12.5%). The concentration of human chorionic gonadotrphin hCG increased highly significantly in the first trimester, but decreased sharply in the second and third trimesters. Thyroglobulin increased in all three trimesters of pregnancy compared to control group, however the greatest elevation was detected during the first trimester. The results of this study showed that the increase of hCG in the first trimester has stimulating effect on thyroid gland, although TSH remains within the normal range, this indicated that the increase of free thyroxine hormone concentration during pregnancy may be due to the increase in hCG only this indicated that the changes of thyroid hormones during p pregnancy were physiological resulted from The pituitary gland has no stimulating effect on thyroid gland during normal pregnancy.