True and honest relationships are not easy to achieve, it requires that both partners loving each other sincerely, being open to each other, no lies, no secrets and trusting each other to keep confidential information even in the face of problems.
In the world today were ulterior motives and selfish gains reigns supreme, being open and trusting someone enough to tell them important and delicate things about your past is like a double edged sword.
However, if one must build an open and honest relationship, there are past that must be told, especially that which can affect the relationship if discovered later. It is better you tell them while the relationship is gathering momentum and allow them time to deal with and come to terms with it. If they decide to break up, they were never meant to be yours. Else, the love grows on with open hearts and clean minds.
Wait for the relationship to get serious, for you to know them more and how easy they run thier mouth before you open up, but do not wait until it’s too late before you tell. Sometimes the secret is actually not the problem but the fact that you could not trust them enough to tell them, that equates to betrayal.
Finally, there are things about your past which is not necessary for your partner to know. If it comes up, you discuss it as a couple and tell the whole truth. However, there are certain past that should be bared open and plain before you tie the knot, withholding such will amount to wickedness. You can withhold telling your partner you had abortions if he is not the type to see it as a problem, however you can not withhold that you lost your womb to one of them, that is witchcraft! Whatever the past is, get to know them first, allow the love mature a bit, then let it out. Let them see you as you are and decide for themself.