Infants have to "learn" to regulate their own breathing over time. It is somewhat instinctual, but is erratic for several months after birth. Infants will instinctively match their breathing patterns to their parent/caregiver when face to face or in close contact with them. If you're worried about increased risk of SIDS make sure you have some face to face, and skin to skin contact every day, and especially before putting them to bed alone for a long period of time.