This question comes up about every three weeks, so you are not alone in this quest.
If you have Hoshimotos disease (antibodies attacking the thyroid) the answer is no. If you dont know if you have Hoshimoto, you need to find out. Supplements may support but not cure hoshis, you need thyroid replacement hormone meds for life. Although people on the 'natural herb' bandwagon jump all over natural dessicated thyroid (pig thyroid), in the end its a manufactured medicine. Works great for many (myself included), but its medicine.
If you just have hypo symptoms due to a 'slow' thyoid, the causes can be many, and sometimes it does not last forever. Can be from pregnacy, all body internal infections, digestive candidas, Celiac disease. In those cases if the cause is treated, the fragile thyroid can return to working order, since the cause was something else to begin with. This is rare, but I know cases of this.
you said you are pregnant. There is no natural treatment for hypo. Hypo in pregnancy must be treated aggressively with medication to prevent complications for you and the baby. Lack of thyroid hormone affects the baby's cognitive development. It can also lead to miscarriage, premature birth, among others.
Your doctor must monitor FT3 and FT4 as well as TSH. FT3 and FT4 should be in the upper half of the reference range. TSH should be between 1 - 2, but TSH should be paid minimal attention and the emphasis is on keeping te FT3 and FT4s high reference range. Sometimes when treated TSH can be very low, but again, look at the FT3 and FT4 and where they are.
Medication is usually levothyroxine. T4.
Testing should be every 4 weeks and meds may need to be adjusted/increased every 4 weeks.
Do not play around with this both your and your baby's health are at risk.. Treatment is critical.