A high-risk pregnancy means a pregnancy with a high probability of adverse pregnancy outcomes for the pregnant woman and fetus, and is applicable when there are risk factors for high-risk pregnancy that can affect pregnancy outcomes. Risk factors involved in high-risk pregnancy include the age of the pregnant woman, medical/surgical diseases that existed before pregnancy, internal/surgical diseases that occurred during pregnancy, obstetric diseases, and diseases that occurred during pregnancy. The most common risk factor for high-risk pregnancies is older pregnancies, such as those over 35 years at the time of delivery, and those over 40 years are at high risk of miscarriage and chromosomal disorders. In the case of elderly mothers, the prevalence of underlying diseases is high, and the occurrence of hypertensive diseases and diabetes during pregnancy increases. Due to the aging of domestic mothers, the rate of high-risk pregnancies is increasing, and more effort is required for prenatal care for them compared to low-risk mothers. In this review, we would like to discuss the matters to be considered in the outpatient examination of high-risk pregnant mothers and the decision on the delivery time for each common disease.