I've been losing a lot of hair lately and i was wondering if it could be because i had a baby 4 months ago or could it be thyroid related?

Could be either: Most likely, in the absence of other symptoms, isolated hair loss after having a baby is probably from just that! if you have other symptoms of thyroid disease such as cold/ heat intolerance/ palpitations, extreme fatigue/ fluctuations in weight/ constipation, then see your dr for a complete evaluation!

Likely the first: A few months post-partum many women start noticing that their hair is thinning out. During pregnancy, the hormones help to retain hair follicles so there is less than the normal shedding of hair. Once pregnancy is over, the accumulated hair will start to fall out naturally. However, post-partum thyroiditis is also pretty common and may need to be considered. Please discuss with your ob.