The authors report a unique recurrent septated cystic hygroma (CH), on two successive pregnancies, at five years interval. The chromosome analysis of the first fetus showed an increase in length of heterochromatin on the long arm of chromosome 1 - 1qh+, a chromosomal polymorphism inherited from mother, 46XX,1qh+,14ps+,21ps+. The karyotype of the second CH, with more severe ultrasound (US) imaging, showed a 69XXX triploidy. The patient took no risk and underwent each time a termination of pregnancy (TOP). The first karyotype is generally considered "normal", although there are few reports linking 1qh+ with low fertility, but this was not the case, the patient having, from a previous marriage, a healthy boy and two TOPs. So, this "particular", but "healthy" karyotype was not a cause for the first CH. The second karyotype highlights a possible causality between the 69XXX triploidy, usually associated with partial hydatidiform mole, and a more severe septated CH in the last fetus. Neither the CHs' appearance nor their recurrence seemed to be family linked, as the two CHs had distinct genetic profiles. We recommend that, once CH is diagnosed, a careful US examination is compulsory for the determination of subcutaneous edema, ascites, pleural and pericardial effusions and cardiac or renal abnormalities; an early genetic work-up is mandatory, by chorionic villus sampling or amniocentesis. However, a "healthy" karyotype does not exclude a severe form, as in our first case of CH. Due to the very poor outcome of fetuses with CH, the patient must be thoroughly informed about the short and the long-term fetal prognosis.