There is no evidence to suggest that mothers are at any higher risk of getting infections in their vaginas or uterus after a water birth. There is also no evidence that mothers should be restricted from using the bath in their labour if their waters have broken. There has been some discussion about mother's infected with viruses such as HIV /AIDS and Hepatitis B and C being at a higher risk of transferring the virus to their baby, to their caregiver (if they do not wear full length gloves and have a cut in their skin) or to other mothers if the bath is not cleaned adequately. For this reason mothers who carry these viruses may be prevented from using the bath or having a water birth.
Infection for the baby
Babies born into water are not at any higher risk of developing an infection when compared to babies born out of water. It is acknowledged that the 'good germs' of the parents (and siblings) are the ones a baby needs to have contact with when first born (hence another advantage of early skin to skin contact with your baby). This is so 'foreign germs' (from strangers and hospitals), don't dominate and increase the chances of the baby developing an infection. This concept is referred to as the 'race to the surface', meaning the first germs to reach a germ free surface will be the likely rulers of the territory.
It is for this reason that caregivers should stay out of the water as much as possible (gloved hands only) unless absolutely necessary, but that partners (and siblings) should be allowed to share the bath with the woman if they wish.
Cleaning the bath / pool
The bath or pool used for the water birth should be cleaned thoroughly with bleach after each use. This is to prevent any possible infection being transferred from one person to another as well as killing germs that can grow in water systems that are not cleaned.