This is from an old ACOG document, which indicates the delivery or global could be reported without a 52 if the doctor does arrive in time to deliver the placenta. This is what we follow.
Several factors determine how a missed delivery can be reported. These factors are, if the physician was in route to perform the delivery, if someone else in the practice performed it, and if it were performed by another physician or qualified nonphysician not associated with your practice.
Generally, when the physician has performed all the components of the global package but misses the delivery, the global package may be reported—that is, if the patient arrived at the hospital while the physician was in route and the nurse ended up performing the delivery but the physician arrived in time to deliver the placenta.
On the other hand, if the physician misses the delivery of the baby and the placenta, but arrives in time to take over from there, then it may be appropriate to bill the global code with a modifier 52 attached (i.e., 59400 -52 for a vaginal delivery). The 52 modifier indicates reduced services, since the physician did not perform the delivery. As such, the physician should consider lowering the fee to reflect the reduction in service. This reporting option should not be selected if anyone else is reporting for the delivery.