Does levothyroxine affect your menstrual cycle?
One drug people take to treat hypothyroidism is called levothyroxine (Levoxyl, Synthroid). It replaces the hormones normally made by your thyroid, and it can cause changes in your period.
Can I get pregnant with hypothyroidism and irregular periods?
Both hypothyroidism and hyperthyroidism (overactive thyroid) are known to prevent ovulation, the monthly process in which an egg is released to be fertilized. If no egg is released, you can't get pregnant, even if you're having regular menstrual periods.