Pregnancy & Thyroid

Pregnancy & Thyroid : Myths & Facts

A lady with thyroid deficiency cannot conceive: On the contrarily hypothyroidism is the commonest treatable cause for female infertility. Chances of pregnancy increase several fold once hypothyroidism is corrected. Lady must continue thyroxine even during pregnancy. Thyroxine requirement often increase during pregnancy.

A lady with hypothyroidism gives birth to hypothyroid baby: It generally does not happen. Baby can have increased risk of thyroid disorder in future life due to genetic factors. But vertical transmission directly from mother to baby does not occur.

Normally thyroid hormones don’t change during pregnancy. Even in pregnant ladies without thyroid diseases their thyroid hormones (T3 & T4) are normally high. In hyperthyroidism drug requirement generally reduce during second trimester. Hence thyroid hormones need to be tested 2-3 monthly during pregnancy.

Thyroid medicines are risky during pregnancy: Thyroid medicines are absolutely safe during pregnancy. In hypothyroid lady thyroxine has several beneficial effects for mother as well as baby like reducing risk of abortion and other pregnancy related complication while it improves IQ (intelligence) in baby if mother takes right dose of thyroxine.

Mental Retardation is very common in baby of hypothyroid mother: It is a quite rare. Thyroid hormone plays a vital role in baby’s growth and brain development. In first 3 months baby is dependent on mother’s thyroid hormone since its own thyroid gland is not developed. Afterwards baby’s own thyroid gland takes over. So if mother’s hypothyroidism grossly uncontrolled, there are some chances of baby getting mental subnormality. In clinical practice this is rarely seen.

Pregnancy related complications are more in lady with thyroid disorders: This is partly true. If untreated or undertreated, hypothyroidism or hyperthyroidism lady carries higher risk of abortion, premature delivery, pregnancy related high blood pressure and other complications. However well treated hypothyroidism or hyperthyroidism lady generally has a smooth pregnancy and delivery without additional risk to mother or baby.

Children with thyroid deficiency cannot live normal adult life: With right dosage of thyroxine and regular treatment, children get normal height, normal physical and mental development, normal pubertal development and normal future adult life.

One should take minimum thyroid medicine during pregnancy. By and large for hypothyroidism mother thyroxine requirement increases during pregnancy. But in hyperthyroidism mother anti thyroid drug requirement decreases during 2nd trimester but again it can increase in 3rd trimester. Hence thyroid testing should be repeated once in 2 or 3 months during pregnancy and dosage of thyroid medicine should be titrated.