Inside the uterus your baby is held within two membranes - the chorion and amnion, collectively known as the sac or bag of waters. The membranes are rather tough and slightly elastic and their function is to provide protection around your baby and to hold the amniotic fluid your baby floats in. Amniotic fluid provides buoyancy so your baby can move freely and exercise their limbs. It also provides a cushion of protection from outside pressure or impact.
The temperature of the amniotic fluid is about 0.5 to 1.0
oCelsius higher than the mother's temperature. If her temperature rises, so does the temperature of the amniotic fluid and her unborn baby's temperature. It is commonly recommended that women avoid very hot saunas and spas (more than 37
oCelsius) and refrain from prolonged, strenuous exercise during pregnancy to avoid overheating their developing baby. You can read more in
physical activity during pregnancy.
Image 1-09 shows the membrane or sac containing the baby and the amniotic fluid.
Updated November 2007
Information sources
Stables D. and Rankin J. Physiology in Childbearing with Anatomy and Related Biosciences. 2004, Bailliere Tindall, Edinburgh.