[The evaluation of the risk of spontaneous abortion at various stages of pregnancy. Study of overall risk and of normal ultrasound pregnancy].

The authors have studied a series of 2,292 pregnancies that were unselected and have calculated from this the risks of spontaneous abortion before the 28th week of the pregnancy that patients have when they come for ultrasonography for the first time in the pregnancy. They have been able to work out the risks of spontaneous abortion even when the ultrasound was normal for the time of pregnancy. The risks diminish as the pregnancy progresses and rise with the mother's age.