641—99.2 (144) Birth registration—five days to one year. The registration of a birth after the statutory time prescribed for filing but within one year from the date of birth shall be registered on the standard form of live birth certificate. Such certificate shall not be marked delayed. In any case where the certificate is signed by one of the parents, a statement giving the reason why the certificate cannot be signed by the attendant must appear on the reverse side of the certificate. The state registrar may require additional evidence in support of the facts of birth or an explanation for the delay in filing in any case where there appears to be reason to question the adequacy of the registration.