Is it normal for newborns to stop breathing for a few seconds an then continue as normal ?

Yes: Newborns must test various patterns of breathing before they sort out how fast/deep to breathe for different activities such as sleep, crying, feeding. They often go through breathing at variable frequency and depth, followed by a 5-10 second pause if they exhaled too much co2.Stopping lets them re-balance.It goes on for about a month.

Irregular breathing: It is very common for even healthy newborns to have irregular breathing, with pauses that last a few seconds. They may also make strange noises when they breathe and have strange facial expressions, especially when sleeping. It is also common for newborns to have blue coloring to hands and feet sometimes, but they should not get blue around the lips or tongue.