N.H. Rev. Stat. § 507-C:4
Notwithstanding any other provision of law, all actions for medical injury shall be commenced within 2 years of the act, omission or failure complained of, except that where the action is based upon discovery of a foreign object in the body of the injured person which is not discovered and could not reasonably have been discovered within such 2-year period, the action may be commenced within 2 years of the date of discovery or of the date of discovery of facts which would reasonably lead to discovery, whichever is earlier. This section applies to all persons regardless of minority or other legal disability, except that a minor under the age of 8 years at the time of the act, omission or failure complained of shall in any event have until his tenth birthday in which to commence an action.
RSA 507-C:4
1977, 417:22, eff. Sept. 3, 1977.