A risk-based prevention paradigm for preterm labor emerged, integrating pharmacologic strategies with psychosocial and epidemiologic risk assessment. The period’s central finding was that progesterone prophylaxis can markedly reduce preterm delivery in high-risk pregnancies, demonstrated in a rigorous double-blind trial, which anchored pharmacologic prevention as a core option. At the same time, research emphasized psychosocial stress, socioeconomic status, prior preterm birth, and inadequate weight gain as key drivers, prompting systematic risk assessment and targeted surveillance. Methodologically, this era advanced from isolated observations to risk-prediction tools that concentrate preventive effort on the minority of pregnancies responsible for most preterm births, shaping both clinical practice and public health planning.