Final answer:
A Soldier should review the Postpartum Fitness At-Home Exercises Video by the 30th week of pregnancy to prepare for postpartum exercises after childbirth.
Step-by-step explanation:
A Soldier should see the Postpartum Fitness At-Home Exercises Video by the 30th week of her pregnancy. It is important to consider that postpartum exercises are intended for after childbirth, and thus suggesting week 30 would allow her a couple of months to familiarize herself with the exercises before the baby is born.
Fetal breathing movements begin around week 20 of pregnancy, indicating significant development has occurred by this time, but postpartum exercise preparation is typically more relevant as the pregnancy nears full term, not at this earlier stage.
By the 40th week, a full-term pregnancy has reached its expected due date, so the timeframe to familiarize herself with postpartum exercises would have passed. Therefore, 30th week of pregnancy is the most appropriate time for a Soldier to begin viewing these exercises in preparation for the postpartum period.