Disclosed are chemically modified heparin or heparan sulfate compounds of formula (I) for use in combination with an agent capable of promoting myometrial contractions of the uterus (e.g., oxytocin) in the treatment of labour arrest (re-establishing effective labour in women when labour arrests). The compounds modification results in reduced anticoagulant activity with an antifactor lIa activity of less than 10 IU/mg and an antifactor Xa activity of less than 10 IU/mg.
