ABSTRACT
In order to study PTD using genetic methodologies, a ‘phenotype’ or clinical picture must be defined.11 The diagnostic signs of preterm labor are nonspecific. Even if specific diagnostic criteria for PTD existed, there would be a great deal of debate about the proper phenotype to study. Therefore, conditions other than early delivery (such as cervical elasticity or length, cervicitis susceptibility, or placental viability) could prove highly informative for genetic and other etiologic investigations. Table 13.2 lists several clinical subtypes of preterm labor that may need to be distinguished to maximize the chances for success.
