TSH Levels During Pregnancy
The reference range for TSH during pregnancy is as follows:
First Trimester: 0.1 – 2.5
Second Trimester: 0.2-3.0
Third Trimester: 0.3 – 3.0
Values out of range need to be investigated and managed accordingly. They may indicate Hypo (underactive) or Hyper (over active) state of the maternal thyroid gland.
Why Are TSH Values Lower During Pregnancy?
Normally, TSH levels are slightly lower in pregnant women than in non pregnancy females. This is because a part of the work that TSH does is taken over by the pregnancy hormones, chiefly HCG.
HCG is highest during the first trimester, lowering TSH to the maximum extent during this phase. Gradually, as pregnancy progress, TSH levels may be seen to rise quietly, though modestly.
Role of TSH
TSH stimulates the thyroid gland, which is a butterfly shaped gland, just below our adam’s apple in the neck. It has two lobes, located one on each side.
On being stimulated, the gland secretes two important hormones, T3 and T4, which control the body metabolism.
Why is TSH So Important in Pregnancy?
The two thyroid hormones are very important for the baby growing in the womb. This is because the baby doesn’t have its functioning thyroid while in womb, and it completely depends upon the maternal supply for this hormone.
T3 and T4 are required for the neurocognitive development of the growing baby. This means the baby’s mental faculty needs this hormone to develop. It afects the baby’s intelligence, thinking power and over all brain tissue development.
Lack of Thyroid Hormones in Pregnancy- Complications
- Preterm delivery of the fetus
- Low birth weight baby
- Low IQ
- Cognitive disorders in the baby.
High TSH During Pregnancy
If your TSH is as high as 2.5 to 3, guidelines recommend measuring of T4 levels.
If T4 is also low, the condition may be called Hypothyroid. TSH levels needs a correction by medications to avoid fetal complications.
If T4 levels are alright, the baby is getting enough of this hormone for development. We may call the situation as subclinical Hypothyroidism.
Here, anti thyroid antibodies need to be investigated. If present, treatment is recommended. Lack of treatment may affect the fetal IQ levels.
Very high TSH levels, say 5 or above, need immediate treatment, regardless of the T4 values.
Hypothyroid, Planning Conception
The need for thyroid hormone by your fetus is maximum in early first trimester. So, if you plan conception, it’s advisable to correct your thyroid status first.
The recommended goal is to bring the TSH levels to 2.5 or low.
Accurate correction of TSH levels is a must. If levels are high, anti-thyroid medication with close monitoring of pregnancy may be given.
It would also be necessary to regularly get TSH levels checked up. This is essential for continuous dose alterations of the medicine, if required.