I have hypothryoidism and have been on medicine for over a decade including 2 pregnancies. During/After pregnancy I have gotten slightly out of whack and just had to change dosage - not a big deal as it wasn't a dramatic change.
This is a very treatable condition - small pill and inexpensive to treat if money is a concern - $4 generics, but a blood test required to check TSH - frequency dependent on TSH level consistency. While not unusual to develop while pregnant (I've heard it could be temporary in these cases), hypothyrodism runs in the family typically with women though men may get as well (my FIL has). Besides me, my mother, grandmother, aunt (developed after menopause) and one female cousin (developed during 2nd pregnancy after age 35) have and my younger sister is borderline. So, ask family members and be sure to tell family members.
Read up on the symptoms, but realize that you may not have any or different ones. When I was diagnosed I had this strange feeling in my arms - incredible aches and pains like they were going to fall off - I was totally clueless and freaked out. This is NOT a normal symptom and the thing is that my TSH wasn't way off to cause that strong of a reaction. Everyone's body reacts differently and your reaction may change over time so it is important to follow your doctors recommendations about how often to get it checked and seek help if something doesn't seem right.
The two common side affects are increased sensitivity to the sun (I find I am more susceptible to the sun now and I see this in others as well so sunscreen has increased importance especially on your face)and dry skin, which I never had other than from constant hand washing due to diaper changes.
One last thing, it typically says you should take your medication without food. I leave on my nightstand and take it when I start to wake up that way it is at least an hour until I eat.
M.