In a clinical trial from 1969 to 1972, Sir Graham Collingwood Liggins and Ross Howie showed that if doctors treat pregnant women with corticosteroids before those women deliver prematurely, then those women's infants have fewer cases of respiratory distress syndrome than do similarly premature infants of women not treated with corticosteroids. Prior to the study, premature infants born before 32 weeks of gestation often died of respiratory distress syndrome, or the inability to inflate immature lungs. Liggins and Howie, then both at the University of Auckland in Auckland, New Zealand, published their results in A Controlled Trial of Antepartum Glucorticoid Treatment for Prevention of the Respiratory Distress Syndrome in Premature Infants in 1972. The study built on experiments Liggins had earlier conducted with sheep. Liggins' corticosteroid experiments changed the way doctors treated pregnant women experiencing preterm labors, and they improved the life expectancy of prematurely born infants.

Sir Graham Collingwood Liggins devoted much of his professional life to obstetric research. Liggins demonstrated that hormones created by the fetus helped initiate labor, rather than hormones originating solely from the mother. Liggins also discovered that cortisol given to pregnant mothers helped delay premature labor, and that it increased the likelihood that premature infants would breathe normally after birth. Prior to cortisol treatment, premature infants often died of respiratory distress syndrome characterized by the inability to inflate immature lungs. Before the clinical application of Liggins' discoveries in the 1980s, premature infants born before 32 weeks of gestation generally died because of respiratory distress.