Using the context and the suffix "-cian," which implies "having a certain skill or art," the term "worst obstetrician" refers to:
d. a doctor who specializes in the care of women during pregnancy and childbirth.
This definition highlights that an obstetrician specializes in a particular area of medicine, specifically focused on pregnancy and childbirth. The term "worst obstetrician" would imply someone who fails to provide proper care in that specialty.