I have been looking at information on primitive reflexes as I was asked by a GP whether it was significant if he could not elicit a Moro reflex at the newborn check. Wikipedia has a nice description of the Moro reflex: “it may be observed in incomplete form in premature birth after the 28th week of gestation, and is usually present in complete form by week 34 (third trimester). It is normally present in all infants/newborns up to 4 or 5 months of age, and its absence indicates a profound disorder of the motor system. An absent or inadequate Moro response on one side is found in infants with hemiplegia, brachial plexus palsy, or a fractured clavicle”.
You need to make sure you are eliciting it correctly first though. I have found a great site from Utah university with little video clips of aspects of a normal and abnormal neurological examination of a 5 day old. Take a look at http://library.med.utah.edu/pedineurologicexam/html/newborn_n.html and watch the 2 Moro examples carefully. Did you know the hands have to come together in the mid-line at the end?