Clonidine: placental transfer and neonatal adaption.

The placental transfer of clonidine was investigated in five pregnancies. Clonidine readily crosses the placenta. The drug elimination in neonates was slow, but the only clinical abnormality was that of a raised arterial blood pressure. Hypertension for at least 24 h was observed in four cases. It is suggested that this may be related to a withdrawal syndrome due to the sudden cessation of the placentally transferred drug.