In-vitro fertilization and embryo transfer: a collaborative study of 1163 pregnancies on the incidence and risk factors of ectopic pregnancies.

In a multi-centric study undertaken on 1163 pregnancies obtained by in-vitro fertilization, a 5% risk of ectopic pregnancies was observed. This figure is certainly higher than that admitted for natural reproduction. After simultaneous adjusting for all variables in our data by means of a multiple logistic regression technique, two factors have specific influence: the therapeutic use of clomiphene citrate which increased the rate of ectopic pregnancies from 3 to 6% and the number of patent Fallopian tubes with a change in ectopic pregnancies rate from 3 or 4% (with 0 or 2 patent tubes) to 13% (with one patent tube). These results suggest various physiologic hypotheses as well as therapeutic considerations.