Spontaneous abortion and interpregnancy interval.

Analysis of 8972 pregnancies and 5089 interpregnancy intervals, computer-registered over 12 years at the Haguenau Hospital Maternity Department, showed that the length of interpregnancy interval may be considered as a risk factor in spontaneous abortion; this was still true after other important known risk factors, i.e. maternal age, parity, previous spontaneous abortion and contraceptive practice, had been taken into account. However, separate analysis of pregnancies according to whether they occur more or less than 1 year after contraception (if used) had been stopped showed that the relationship between a long interval and spontaneous abortion was only significant for subfertile women who took longer than 1 year to conceive. This supports the hypothesis that the same mechanism is involved in the aetiologies of spontaneous abortion and of difficulty in conceiving.