In Defence of the Amniotic Sac
By Rachel Reed of Midwife Thinking
“Artificial rupture of membranes (ARM) aka ‘breaking the waters’ is a common intervention during birth. However, an ARM should not be carried out without a good understanding of how the amniotic sac and fluid function in labour. Women need to be fully informed of the risks associated this intervention before agreeing to alter their labour in this way.”
During pregnancy
The amniotic sac protects and prepares baby by:
Cushioning any bumps to the abdomen.
Maintaining a constant temperature.
Allowing the movement essential for muscle development.
Creating space for growth.
Protecting against infection – the membranes provide a barrier + the fluid contains antimicrobial peptides.
Assisting lung development – baby breathes fluid in and out of the lungs.
Taste and smell – the smell of amniotic fluid has been found to have a calming effect on newborns (Varendia et al. 1998).
After 40 weeks gestation around 20% of babies will pass meconium into their amniotic fluid as the bowels reach maturity and begin to work. This is perfectly normal and is not a sign of distress. This meconium is diluted and processed with the amniotic fluid as described above.
