Final answer:
Fetal breathing movements begin around week 20 of pregnancy and play a significant role in the development of the respiratory system. By 34 weeks, the fetal heart rate should be able to peak 15 bpm above baseline for a certain duration of time as a result of these movements.
Step-by-step explanation:
In order for the fetal heart rate (FHR) to peak 15 bpm above baseline for at least a certain number of seconds by 34 weeks, we need to consider the concept of fetal breathing movements. Fetal breathing movements begin around week 20 of pregnancy, and they involve the rhythmic contractions and relaxations of the diaphragm and chest muscles, which result in the movement of amniotic fluid in and out of the fetal lungs.
These movements are important for the development and maturation of the respiratory system, as well as the maintenance of a stable FHR. The movement of amniotic fluid in and out of the lungs helps to exercise the respiratory muscles and stimulate the production of surfactant, a substance that helps the lungs expand and prevents them from collapsing.
By 34 weeks of pregnancy, it is expected that the fetus will have developed the ability to achieve the desired FHR increase for a certain number of seconds as a result of these fetal breathing movements. However, it's important to note that individual variations may occur, and it's best to consult with a healthcare provider for specific information regarding a particular pregnancy.