On the other hand, there is no neural vascular regulation, and catecholamines have only little effect.The fetoplacental circulation is vulnerable to persistent hypoxia or intermittent hypoxia and reoxygenation, which can lead to generation of excessive free radicals. This may contribute to pre-eclampsia and other pregnancy complications. It is proposed that melatonin plays a role as an antioxidant in the placenta.This begins at day 17–22. Birth
Placental expulsion begins as a physiological separation from the wall of the uterus. The period from just after the child is born until just after the placenta is expelled is called the "third stage of labor". The placenta is usually expelled within 15–30 minutes of birth. Placental expulsion can be managed actively, for example by giving oxytocin via intramuscular injection followed by cord traction to assist in delivering the placenta. Alternatively, it can be managed expectantly, allowing the placenta to be expelled without medical assistance. Blood loss and the risk of postpartum bleeding may be reduced in women offered active management of the third stage of labour, however there may be adverse effects and more research is necessary.The habit is to cut the cord immediately after birth, but it is theorised that there is no medical reason to do this; on the contrary, it is theorised that not cutting the cord helps the baby in its adaptation to extrauterine life, especially in preterm infants. Microbiome
The placenta is traditionally thought to be sterile, but recent research suggests that a resident, non-pathogenic, and diverse population of microorganisms may be present in healthy tissue.
Oil in water emulsion creams, or petrolatum, applied as barrier agents prior to a shower or bath may control symptoms. Therapeutic effectiveness of various classes of drugs differs from case to case. Treatment
There is currently no treatment that will permanently cure the condition. Avoidance of water is recommended as a first line of defense, and most treatments are palliative in nature rather than curative
Oral or topical antihistamine
Topical corticosteroids: specifically stanozolol. Phototherapy
Barrier cream

See also
Aquagenic pruritus
Aquadynia
Cholinergic urticaria
Solar urticaria
List of cutaneous conditions


== References ==