The present paper considers genetic risk factors associated with preterm births. We investigated two main hypotheses, namely: 1) Whether there is a detectable genetic or at least a family resemblance component that may predispose a mother to give birth prematurely and 2) whether the risk to preterm delivery can be predicted in the early stages of pregnancy by means of associated morphometric traits and biochemical genetic markers. Our data and published literature certainly point to the existence of a significant family component, although the findings are still scanty for precise determination of genetic and cultural heritability components. In particular, the available data on family correlations in gestational age do not allow one to distinguish between the contribution of the fetus's genotype from the maternal environment and maternal genotype. Parent‐children and marital correlations in gestational age, critical for nuclear family analysis, are rather difficult, if not impossible, to obtain. Therefore, we discuss in the present paper several realistic path analysis models for estimating the relative contribution of genetically inherited and environmental components. Some biochemical markers and also morphological asymmetry correlate with a predisposition to preterm delivery. Again, however, more empirical data are needed to properly assess these relationships.