Relationship between maternal and fetal lung growth.

This study analyzes the relationship between the maternal and fetal lungs, in rats in relation to litter size, to determine whether the enlargement of maternal lung during pregnancy is concurrent with that of the fetal lung. Pregnant albino rats were sacrificed on gestation day 21 (term 22 days). Maternal lung growth was assessed by measuring the lung weight, lung air volume and lung DNA content, and the fetal lung growth by lung DNA content. The findings were as follows: (1) no differences were noted between the lungs of non-pregnant rats and pregnant rats with small litter size (1-4); (2) pregnant rats with large litter size (10-18) had larger lungs than rats with small litter size; (3) there was a direct relationship between cellularity (DNA content) of the fetal lung and maternal lung when the latter underwent a growth change during pregnancy; (4) no relationship in cellularity was found between the maternal lung and placenta nor between the fetal lung and placenta. The results suggest that factors or processes which regulate the growth and dictate the size of the maternal lung during pregnancy similarly influence the fetal lung.