[Spontaneous fetal mortality. Role of maternal age, parity and previous abortions].

Analysing the reproductive biographies of samples of women has made it possible to clarify the role of various factors in bringing about a risk of spontaneous fetal death during the reproductive life of the mother. However, attention must be paid to the difficulties in observing the cases and measuring parameters. To make the various features comparable it is necessary to distinguish between apparent intra-uterine mortality (the pregnancy being diagnosed by the woman), recognisable (the pregnancy is diagnosable clinically) and total (from the time of fertilisation). The effect of maternal age is definite and quite independent of parity. Apparent intra-uterine mortality rises from about 120 per 1,000 pregnancies at the age of 20-24 to 200 per 1,000 at 35-39 and 270 per 1,000 at 40-44. If there has been no previous abortion the risks generally are less than 150 per 1,000, but if there has been even one previous abortion they become practically double. This discontinuity can be interpreted as showing the existence of marked changes between women as far as this risk is concerned.