MORE INFO:

Developing babies are surrounded by amniotic fluid, and their lungs are filled with this fluid. By 10–12 weeks of gestation, developing babies begin taking “practice” breaths. But these breaths provide them with no oxygen, and only refill the lungs with more amniotic fluid.

SOURCE:

https://www.medicalnewstoday.com/articles/318993#:~:text=Developing%20babies%20are%20surrounded%20by,lungs%20with%20more%20amniotic%20fluid.