Baby drinks, swallows and breathes using their natural rhythm, like on a breast. New Natural Response Teats are different from free-flow teats. Like breastfeeding, it could take a few tries to get it right. That's perfectly natural.
If you have tried the same teat a few times with little or no success, it may mean your baby needs a different teat flow. The flow of milk is linked to how enthusiastically or steadily they drink as they develop, regardless of age. If your newborn baby is consistently not taking enough milk throughout the feeding sessions or has complications in getting milk, switch to a teat with a higher flow rate.
Does your baby seem frustrated or fall asleep during feeds? If so, try a higher flow rate. Is your baby gulping or is milk leaking from their mouth? A lower flow rate may help.