Preterm birth (i.e. birth before 37 completed weeks of gestation) is the leading cause of neonatal mortality globally. There is an urgent need for new agents to prevent preterm birth, thereby reducing adverse outcomes for newborns. An initial target product profile (TPP) for drugs to prevent spontaneous preterm birth was developed and published by external parties. Following the identification of an unmet public health need, WHO has considered the already published TPP as the basis for developing a WHO TPP. The purpose of this TPP is to guide product developers and funders on the key characteristics and desired attributes of preventive agents that should be administered to pregnant women at increased risk of spontaneous preterm birth. This TPP outlines the minimal and preferred characteristics of a medicine that should: - reduce the likelihood of preterm birth and thus prevent (or mitigate) adverse newborn outcomes due to prematurity; - have an excellent safety profile during pregnancy; - be suitable for prescription or administration by skilled health personnel in any health care setting where pregnant women receive antenatal care, including in LMICs; - be commenced early in pregnancy and can be continued throughout pregnancy, as required.