O99: Other maternal diseases classifiable elsewhere but complicating pregnancy, childbirth and the puerperium

The group of conditions known as Other Maternal Diseases Complicating Pregnancy, Childbirth and the Puerperium, includes various health issues in a pregnant woman that, while primarily classified under other categories, can complicate pregnancy, delivery, and the postpartum period. These can include diseases like diabetes, heart disease, kidney problems, or thyroid disorders, among others. These diseases can interfere with the normal physiological adaptation to pregnancy, potentially leading to difficulties like gestational diabetes, preeclampsia, preterm birth, or postpartum bleeding. Symptoms vary widely depending on the underlying condition, and can range from mild to severe. The progression of these diseases can also fluctuate depending on the specific disease, the woman's overall health status, and the care received during pregnancy. These conditions can impact various body systems, depending not only on the system primarily affected by the chronic condition, but also on how that condition interacts with the physiological changes of pregnancy.