If you are having symptoms get it checked at any point, but at 6 months and a year at least is good. I usually have hypothyroidism, but at one point when the girls were about 6 months old I started losing weight and bing totally hyper...everyone noticed it was so bad, and I got checked and had to really change my meds.
It is really common for thyroid levels to be messed up in women, and after birth even more common. If you have symptoms of low or high get checked out. Without my meds I am a total slug and can't get out of bed, but with one tiny pill a day I am all bright-eyed and bushy-tailed. Well, not really, but you see what I mean

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As the saying goes, when a door slams shut in one place a window opens somewhere else. After staring at the door for many years, it finally occured to me to go look for the open window. I discovered I like sunlight and warmth much more than peeling old doors anyway, so I climbed out the window and reveled in my discovery. I will never sit behind a closed door again, no matter how comfortable my chair becomes. Me
Mel, I'm glad you found your own open window and stepped through it.