Early pregnancy: Levothyroxine prescribed with levels normal

[Raspberry534]

I (F 39) am pregnant (3 wks, 5 days) and today I was prescribed 12.5 micro grams of Levothyroxine by my new endocrinologist. My blood results of TSH, fT3 and fT4 are normal:

TSH: 2.78 [Ref range 0.27 - 4.2]

fT3: 4.06 [Ref range 3.1 - 6.8]

fT4: 14.92 [Ref range 12 - 22]

The endocrinologist told me the medication is not for me but 'for the baby'. I don't have a history of hypothyroidism, I did have 2 thyroid nodules (under 1 cm) earlier this year but they both have disappeared by now.

During the appointment, I mentioned I have problems swallowing (due to my multiple sclerosis) and that I have been fatigued.

Not sure, if it's related to the prenatal supplement but while taking prenatal iodine early this year, my TSH level rose over the limit (5.1 mIU/L [Ref range 0.27-4.2]) a couple of times. Thankfully it came back two-three months later after discontinuing. This particular endocrinologist wasn't however aware of my TSH fluctuation.
I'd like to ask if it's a normal practice to prescribe Levothyroxine in pregnancy and what the reasons could be behind my prescription.

Thank you very much for any ideas and comments!

[specialmom]

So, from what I've read, some women have a dip in thyroid hormones when first pregnant. This can increase risk of pregnancy loss. They then add levothyroxine to counter this and to help prevent early pregnancy loss. 85% of women with hypothyroidism have a lowering of their thyroid numbers when pregnant. So, I think your doctor is trying to give your pregnancy the best environment and chance to get out of the first trimester intact. Does that make sense? It's preventative to help decrease odds of miscarrying due to worsening hypothyroidism that happens frequently during pregnancy. You may not be fully hypothyroid normally but some of your numbers are close to the range where the doctor may be worried if it goes lower, it could impact the pregnancy. Congrats on the baby, by the way.