If the mother drowns in VERY cold water, the baby may last a little longer if it cools down enough, but when the mother's heart stops so does all the blood flow.
When blood stops flowing in an adult, this is what happens:
30-60 seconds - unconsciousness
3-4 minutes - brain death begins
5-6 minutes - death
Have Fun,
Jeff
except the baby is inside the mother bathing in warm liquid. My guess is that it would take too long for the amniotic fluid to cool down enough to cool down the baby enough before oxygen deprivation kills it...