Dr. N K Narayanan Endocrinologist & Diabetologist, Apollo Hospitals, Chennai
Complex factors come into play during pregnancy. “Thyroid hormones of a pregnant woman are crucial for normal development of a baby’s brain and nervous system. During pregnancy, the baby is totally dependent on the mother’s supply of thyroid hormones till 18-20 weeks of pregnancy,” says Dr. N K Narayanan, Endocrinologist & Diabetologist, Apollo Hospitals, Chennai, Adjunct Professor, The Tamilnadu Dr MGR Medical University.
Thyroid Levels Determine Health
The intricacies of the functioning of the small butterfly shaped gland in the neck determine the health status of the mother and the foetus.
Hypothyroidism occurs when the thyroid gland is underactive leading to low levels of thyroid hormones. Symptoms of hypothyroidism include fatigue, lethargy, weight gain, constipation, sleeplessness and irregular periods in women. Low thyroid levels affect ovulation in women who may also experience excessive bleeding. Women with suboptimal secretion of thyroid hormones will have problems getting pregnant.
Excess production of thyroid hormones leads to hyperthyroidism that gives rise to symptoms like weight loss, palpitation, tremors and shakes, excessive sweating etc. Periods will be frequent with sparse bleeding and if women with undetected hyperthyroidism get pregnant, it can lead to miscarriage.
Thyroid levels in men also play a role in the pregnancy of the spouse. Hypothyroidism in men leads to low quality of sperm while hyperthyroidism leads to low sperm count. If the thyroid status is normalised it improves the chances of conception in the spouse.
Gestational hypothyroidism
Sometimes, even though the mother has adequate supply of thyroid hormones for herself, once she conceives if she is not be able to meet the increased demand for the thyroid hormones, then she develops gestational hypothyroidism. Once the mother receives hormone replacement supplements, her thyroid hormone levels would become optimal.
Implications of Mother’s Thyroid Levels for the Baby
Though hyperthyroidism is much less common it is important to correct the hormone levels before conception. Untreated hyperthyroidism during pregnancy may lead to miscarriage, premature birth, low birth weight of the baby and rarely, congestive heart failure. On rare occasions, it may affect the baby’s thyroid, triggering over production of thyroid hormones or early closing of the soft spot in the baby’s skull.
In hypothyroidism during pregnancy the health hazards include anaemia, miscarriage, low birth weight, still birth and on rare occasions, congestive heart failure.
Medical Management of Thyroid Levels during Pregnancy
Low thyroid levels managed with thyroxine hormone replacement is safe throughout pregnancy. Whereas for overactive thyroid, doctors are cautious with the medicines. “We monitor pregnant women with hyperthyroidism more frequently than those with hypothyroidism, and try to bring down the levels as quickly as possible, so that the baby is not affected,” says Dr. Narayanan.
In rare instances, when thyroid levels cannot be brought down with medicines alone, they go for surgical removal of the thyroid gland during second trimester. The other option of radioiodine therapy is avoided during pregnancy because it can damage the baby’s thyroid gland.
Gestational transient thyrotoxicosis happens when pregnancy related hormone hCG triggers higher thyroid hormone levels in women with no history of elevated thyroid levels. Other than preventing dehydration, usually this condition does not require medication. Postpartum thyroiditis occurs in some women 5 to 7 months after delivery, when their thyroid levels transiently go high and then dip low. Among women who require thyroxine replacement for this condition, about 70% require medicines for a short time only, while about 30% have to continue hormone replacement throughout their lives.
With effective medical management most women get well under control and go through their pregnancies without complications. The family should ensure a stress-free ambience for the mother and child to be healthy. Planned pregnancy is the way to go.
