Fertility and Pregnancy: The Impact of Thyroid Disorders in Women

By Dr.Pratyusha Gunreddy, MBBS,MS(OBG),FRM, Consultant Fertility Specialist Ankura Hospital for Women and Children

Thyroid disorders are among the most common endocrine conditions affecting women, significantly influencing fertility and pregnancy. The thyroid gland plays a crucial role in regulating metabolism, hormone production, and reproductive health. An imbalance in thyroid hormones—either hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid)—can disrupt ovulation, menstrual cycles, and overall reproductive function.

The classic definition of SCH is a thyrotropin (thyroid-stimulating hormone [TSH]) level greater than the upper limit of the normal range (4.5–5.0 mIU/ L) with normal free thyroxine (FT4) levels. With this definition, the incidence of SCH in the reproductive-age population is approximately 4%–8%

Recommendations for SCH vary between the American Society for Reproductive Medicine (ASRM), the Endocrine Society, the American Thyroid Association (ATA), the American Association of Clinical Endocrinologists, the American College of Obstetricians and Gynecologists (ACOG), and others

Available studies used a wide range of TSH levels to define SCH, ranging from >2.5–10 mIU/L, meaning various studies measured different exposure levels and are challenging to compare.

In addition, the goal of achieving a TSH level <2.5 mIU/L has resulted in significant delays in women receiving the appropriate infertility treatment or initiating an IVF treatment cycle. Thyroid Disorders and Fertility Hypothyroidism and Infertility Hypothyroidism occurs when the thyroid gland produces insufficient hormones, leading to symptoms like fatigue, weight gain, depression, and irregular periods. The deficiency of thyroid hormones can impact ovulation, reducing the chances of conception. In some cases, it can lead to anovulation (absence of ovulation), making it difficult for women to conceive. Hypothyroidism is also associated with an increased risk of polycystic ovary syndrome (PCOS), a condition that further affects fertility. In India, approximately 10-12% of the population is affected by hypothyroidism, with women being more vulnerable. According to a study by the Indian Thyroid Society, nearly 22% of women in Hyderabad suffer from thyroid disorders, impacting their reproductive health significantly. Hyperthyroidism and Fertility Issues Hyperthyroidism, caused by excessive thyroid hormone production, leads to symptoms such as weight loss, rapid heartbeat, anxiety, and irregular menstrual cycles. Women with untreated hyperthyroidism may experience difficulty in conceiving due to hormonal imbalances and increased metabolic activity that can alter reproductive hormone levels. Conditions like Graves’ disease, an autoimmune disorder, are often responsible for hyperthyroidism and can further complicate fertility. In India, the prevalence of hyperthyroidism is lower than hypothyroidism but still affects around 1-2% of the population. Hyderabad-specific hospital records indicate that 15% of thyroid-related cases among women are due to hyperthyroidism. Thyroid Antibodies and Autoimmune Infertility Autoimmune thyroid conditions, such as Hashimoto’s thyroiditis, can lead to the production of thyroid antibodies that interfere with ovarian function and embryo implantation. Studies indicate that elevated levels of thyroid peroxidase (TPO) antibodies are linked to an increased risk of miscarriage and infertility in women. Thyroid Disorders and Pregnancy Complications Thyroid disorders, if left untreated during pregnancy, can lead to serious maternal and fetal complications. Some of the major risks include: Miscarriage and Preterm Birth: Uncontrolled hypothyroidism or hyperthyroidism can increase the likelihood of early pregnancy loss and preterm labor. In India, thyroid disorders contribute to 8-12% of pregnancy complications, with Hyderabad recording a higher prevalence of 14% due to lifestyle and dietary factors. Preeclampsia: Hypothyroidism is associated with high blood pressure and proteinuria during pregnancy, increasing the risk of preeclampsia. Low Birth Weight and Developmental Issues: Poor thyroid function in the mother can impact fetal brain development, leading to cognitive impairments and growth restrictions in newborns. Studies from Indian hospitals indicate that nearly 20% of infants born to mothers with untreated hypothyroidism have low birth weight. Gestational Hypertension: Abnormal thyroid hormone levels can lead to high blood pressure during pregnancy, posing health risks to both the mother and baby. Managing Thyroid Disorders for Healthy Fertility and Pregnancy Thyroid Function Tests: Women planning to conceive should undergo regular thyroid function tests (TSH, T3, and T4) to detect any imbalances early. In Hyderabad, major fertility centers report that nearly 30% of infertility cases are linked to thyroid dysfunction. Medication and Treatment: Hypothyroidism is usually treated with levothyroxine, while hyperthyroidism may require anti-thyroid medications, beta-blockers, or, in severe cases, radioiodine therapy or surgery. Diet and Lifestyle Changes: A well-balanced diet rich in iodine, selenium, and zinc can support thyroid function. Managing stress, avoiding excessive caffeine intake, and maintaining a healthy weight can also improve reproductive health. In India, iodine deficiency is a major cause of thyroid disorders, with over 42 million people affected. Monitoring During Pregnancy: Pregnant women with thyroid disorders should undergo frequent monitoring and medication adjustments to ensure optimal hormone levels and a healthy pregnancy. Conclusion Thyroid disorders play a vital role in female fertility and pregnancy outcomes. Early diagnosis, proper treatment, and lifestyle modifications can help women with thyroid imbalances conceive successfully and have a healthy pregnancy. Women experiencing difficulty in conceiving or recurrent miscarriages should consult an endocrinologist and gynecologist for comprehensive thyroid evaluation and management. Given the increasing prevalence of thyroid disorders in Hyderabad and across India, awareness and early intervention are crucial to improving reproductive health outcomes.