Miss. Code § 91-5-5
If a testator or testatrix, having a child or children born at the time of making and publishing his or her last will and testament, shall, at his or her death, leave a child or children born after the making and publishing such last will and testament, the child or children so after-born, if unprovided for by settlement and neither provided for nor disinherited, but only pretermitted, by the last will and testament, shall succeed to the same portion of the father's or mother's estate as such child or children would have been entitled to if the father or mother had died intestate, towards raising which portion the devisees and legatees shall contribute proportionately out of the parts devised and bequeathed to them by the same will and testament, in the same manner as is provided in the case of posthumous children.
Miss. Code § 91-5-5