Preterm birth occurs for a number of reasons.

However most preterm births occur spontaneously.

Often in all these cases no cause is identified.

For a few years, therefore, the attention of researcher has been concentrating more and more on genetic predisposition to preterm birth and to the duration of pregnancy.

The available literature has provided certain evidence of family and intergenerational influences on children with low birth weight or preterm.(7;8;9;10;11;12)

A study based on birth certificates and fetal deaths of the state of Georgia between 1980 and 1995 confirms the absolute constitution predisposition to preterm birth. (13; 12) The cohort study of the national National Maternity and Infant Health Survey has shown a strong family aggregation on low birth weight and preterm birth in White and African American populations. (14; 13)

Family and intergenerational influence on preterm birth may be attributable to environmental factors, genetic factors or both. Family inheritance was about 30% in the Australian Population (14; 15), and 40% in the Swedish Population. (15; 16)

As shown below, with recent advances in human genetics and molecular biology, the assessment of genetic contributions to the identification of preterm birth risk and the duration of pregnancy has progressed to the point of providing a formidable instrument for prevention and control of pregnancy.

In this way, certainly it is possible to predict more than half of the preterm births in total and almost all of those cases where there are no clinical risk conditions such as, in particular, those listed in points B, C, D and E of TAB 1.