I understand that all O codes in Chapter 15 will need to have a Z3Acode (weeks gestation attached, but do I need to use the Z3Acodes as the secondary code when using the normal pregnancy codes of Z34 which is from Chapter 21? The guidelines state using Z3A codes as secondary when using Chapter 15 codes which are the O codes, but nothing is stated in the guidelines for Chapter 21 when using Z34 codes. Can anyone clarify for me whether I need to use Z3A codes as a secondary diagnosis when using Z34 codes?Thanks!