Preconceptional thyroid autoimmunity, dysfunction and associated factors in nulliparous Indian women

Hypothyroidism in young women is associated with adverse reproductive outcomes. There are no previous population-based studies regarding the prevalence of hypothyroidism or thyroid autoimmunity in nulliparous preconceptional women. The current study was done to determine the prevalence of thyroid autoimmunity and thyroid dysfunction in newly married nulliparous Indian women. Multistage sampling was employed to enrol married nulliparous women of 18-35 years age group from four socio geographic regions of Thiruvananthapuram district (urban, rural, coastal and hilly) based on ‘eligible couple register’ with the help of community health workers. Trained staff collected demographic and medical information and also conducted limited clinical examination for vital signs, goitre and anthropometric measurements. Biochemical investigations including serum thyrotropin (TSH), total thyroxine(T4), anti-thyroid-peroxidase (TPOAb) antibody were done in all participants. A total of 1,507 women were enrolled, of whom 1,379 with complete metabolic, anthropometric, and thyroid profile data were included in the final analysis. The prevalence of overt hypothyroidism was 3.0% (n=42) and subclinical hypothyroidism was 9.7% (n=134). The prevalence of TPOAb positivity was 19.2%. In euthyroid, subclinical hypothyroid and overt hypothyroid population, TPOAb positivity was 13.28%, 42.7% and 71.8% respectively. Fasting serum insulin, triglyceride, low-density lipoprotein (LDL) levels were higher in the hypothyroid group compared to euthyroid females. No associations with metabolic parameters were seen for TPOAb positivity. One in eight preconceptional South Indian women suffer from hypothyroidism. Thyroid autoimmunity contributes to hypothyroidism in participants with higher TSH values whereas insulin resistance may contribute to subclinical hypothyroidism. Screening for hypothyroidism in the preconceptional period is recommended.