An obstetrician-gynecologist says: “The week 24 – the beginning of the viability of the child, i.e its ability to live independently.
Until now, the lungs of the child were not functioning, but now, in the 24th week of pregnancy, on the ends of the capillaries that bring blood there are formed terminal sacs, separated by a thin film of air-filled (after the birth) alveoli. Until this moment the oxygen from the lungs does not enter the circulatory system. Now the surfactant is produced. Its production is increasing rapidly at the final weeks of pregnancy.
The surfactant forms a thin film on the walls of the capillary follicles, because of what they are not closed under the influence of respiration. The weight of the child is now about 625-650 g, height 28 cm.”