Anything in excess is not a great idea. Hajmola does not have any ingredient that is harmful for a pregnancy but it will have some taste enhancers as well as some sugar and also preservatives. It's best avoided.

It's not healthy though, craving is good to be satisfied however too much without count is not good. You can try to cook some recipe which is sour using tamarind or dry mango powder but eating hajmola without count is not good at all