(This was my answer to a question on Quora)
Well, investors understand that all plans do not go as planned. And therefore you may have had a plan to achieve something with the earlier round you raised but were not able to. Therefore there is no valuation increase in the bridge round you are raising.
As long as you have a plan to get back on track that helps you develop a sound foundation for a business, in my view, future valuations should not get affected But, as you would agree, valuations are not dependent on any single dimension and there will be several factors to consider whether this will impact future investments.
(Typically, if your earlier round investors have invested in the next round, even if at the same valuation, it is a signal that there is belief in the concept/model/opportunity/value proposition… and faith in you… and that is a strong signal. On the other hand, earlier round investors not participating in the subsequent bridge round, even if it is at the previous valuation usually will trigger some questions.).