Obstetrics Branch of medicine that attends to the care of childbearing women during preg- nancy, childbirth and the puerperium, particularly concerned with deviations from the norm. Pandemic A worldwide epidemic (e.g. bubonic plague in 14th century Europe, or the AIDS pandemic). Pathogen Parasite causing disease, usually a microorganism. Pre-clinical (disease) The stage of a disease after the infected individual is not displaying clinical signs or symptoms, which will ultimately progress to clinical disease. Puerperal Pertaining to the period after childbirth (the puerperium). Puerperium The six to eight week period following childbirth, during which the mother’s body returns to its pre-pregnant state, with the uterus returning to its normal size. Sub-clinical (disease) A disease or condition, which is not clinically apparent, and is not des- tined to become so.