Yes pacifiers are very safe for newborn babies and in fact a pacifier when given to a newborn baby can actually help to reduce the risk of SIDS "Sudden Infant Death Syndrome".
Although if the baby is breastfed it's best to wait to give the baby a pacifier until the baby is 3 to 4 weeks old.
Even when your baby is napping it's good to let them suck on the pacifier to help the baby sleep better and also reduce SIDS then as well.
Pacifiers are great for newborn babies and older babies. But the pacifier should be taken away before the child's second or third birthday.
Prolonged pacifier use in children older than 2 to 3 years old especially during the day can lead to crooked teeth and cause speech delays as well.