It is preferable, when photographing a newborn, to work with the baby when they are in a deep sleep.  This is not accomplished in all sessions for a variety of reasons.  I ask the parents to give me the best time of day for the baby, who at two weeks old, are on their own schedule.  It is ideal that they eat just prior to, or just after I arrive, and they are rocked to sleep.  Once they are sound asleep, it is possible to "mold" them into positions they wouldn't naturally get into on their own.