Final answer:
A pregnant sailor must provide medical documentation confirming the pregnancy to be waived for the PHA, which helps in making informed decisions about her duty status.
Step-by-step explanation:
A pregnant sailor needing to be waived for the PHA (Periodic Health Assessment) should provide appropriate documentation from her healthcare provider. The documentation should confirm the pregnancy and indicate any medical advice regarding limitations or precautions. In accordance with military health and readiness protocols, this documentation will allow her commanding officers and medical personnel to make informed decisions regarding her duty status and the waiver for the PHA.