Hyaline membrane disease and acidosis at birth in twins.

To test the hypothesis that the increased incidence of hyaline membrane disease in second-born twins is related to acidosis at birth, umbilical arterial [H+] was measured in 26 sets of premature twins. Although overall Twin B had a lower Apgar score than Twin A, there was no difference in their [H+]. If the delivery interval was prolonged over 8 minutes then Twin B infants were more acidemic and had lower Apgar scores. Infants with hyaline membrane disease had lower Apgar scores, but were not more acidemic than infants without respiratory distress. Our data suggest that acidosis at birth is not an important factor in the development of hyaline membrane disease.