Synthesis of oestrogens occurs, during the greater part of pregnancy, in the placenta starting with two fetal precursors: DHA-S and 16 OH DHA-S. In the case of a deficit in sulphatase, an enzyme which is mainly localised in the placenta, these precursors cannot be transformed so that the level of oestrogens stays very low, without the level of secretion of progesterone being altered. Faced with such hormonal abnormalities it is worth while remembering the diagnosis of placental enzyme deficiency. In fact, this abnormality has no repercussions on the progress of the pregnancy and carries no danger for the fetus. It is therefore unnecessary to carry out untimely treatments thinking: fetal distress or adrenal agenesis be it primary or secondary (due to anencephaly) will occur. The diagnosis depends on simple dynamic tests: the mother receives an injection of free DHA and DHA-S, and enzyme study of the placenta can be confirmed in vitro. There seems to be a link between this abnormality and the sex of the fetus. All cases were followed by the birth of a normal boy. Finally, placental suphatase deficiency is rare, but it would appear that increased usage of hormone levels will reveal a rising number of such cases.