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Rajeev Agarwal: TSH 3.1 Before Pregnancy

Rajeev Agarwal/LinkedIn

Nov 9, 2026, 17:17

Rajeev Agarwal: TSH 3.1 Before Pregnancy

Rajeev Agarwal, Director of Renew Healthcare, shared on LinkedIn:

” ‘My TSH is 3.1. Do I need a thyroid tablet before pregnancy?’

Women often come to me with a TSH report flagged in red, a thyroid tablet already prescribed, and a fear that their thyroid is why they are not pregnant.

A TSH of 3.1 on its own is usually not a reason to start a tablet.

Why:

TSH changes with illness, poor sleep and even the time of day. One result can mislead.
A large UK trial included 952 women with normal thyroid levels but positive thyroid antibodies, who had miscarriages or trouble conceiving. Half took a thyroid tablet, half a dummy tablet. About 37 in 100 had a baby either way.

What guidelines say:

A TSH between 2.5 and 4, when trying to conceive, is a grey zone. Treating it is an option, not a must.
A truly underactive thyroid is different. It must be treated before pregnancy.

What I do:

Repeat a borderline TSH before starting any tablet.
Add two more tests: free T4 and thyroid antibodies.
If TSH stays above 4, I treat.
If TSH is above 2.5 with antibodies and past miscarriage, we decide together.
A single TSH of 3.1 and nothing else: I usually don’t treat.
If you do start a tablet, recheck in 6 to 8 weeks, and again once you are pregnant.

This is part of the PREPARE method: check properly, then decide.

Don’t just conceive, preconceive.”

Rajeev Agarwal: TSH 3.1 Before Pregnancy