SPHK1 and preeclampsia: Human placentae from 5-9 weeks of gestation, when intrauterine oxygen tension is low, exhibited heightened long chain ceramide (Cer14:0, Cer16:0, Cer18:0, Cer 18:1) and sphingosine content and reduced ASAH1 and SPHK1 expression, highlighting the relevance of low oxygen in regulating sphingolipid metabolism under physiological (placental development) and pathological (Phd2−/− cKO induced preeclampsia) conditions.