Final answer:
Puerperal sepsis, caused by infections following childbirth, is the leading cause of perinatal infections with a high mortality rate. It can lead to severe conditions like peritonitis and septicemia.
Step-by-step explanation:
Puerperal sepsis is the leading cause of perinatal infections that have a high mortality rate. This serious condition mainly affects women who have recently given birth, leading to complications such as peritonitis, septicemia, and oftentimes death. Ignaz Semmelweis, a Hungarian obstetrician, was instrumental in identifying the infectious nature of this disease in the 1840s and established early antiseptic procedures which greatly reduced mortality rates from puerperal fever.
Infections such as those caused by S. agalactiae can result in neonatal meningitis, which is a severe condition that can manifest soon after birth or as a late-onset disease. Pregnant women are also vulnerable to Listeria infections, which can cause miscarriages, stillbirth, or fatal infections in newborns. Other serious perinatal complications can arise from neonatal tetanus, which is particularly dangerous in regions with poor sanitation and where maternal immunization is not prevalent.