Congenital refers to a condition or trait that exists at birth. Congenital conditions or traits may be hereditary or result from an action or exposure occurring during pregnancy or at birth, or they may be due to a combination of these factors. Congenital disorders can be defined as structural or functional anomalies that occur during intrauterine life. Also called birth defects, congenital anomalies or congenital malformations, these conditions develop prenatally and may be identified before or at birth, or later in life. An estimated 6% of babies worldwide are born with a congenital disorder, resulting in hundreds of thousands of associated deaths. However, the true number of cases may be much higher because statistics do not often consider terminated pregnancies and stillbirths. Some congenital disorders can be treated with surgical and non-surgical options, such as cleft lip and palate, clubfoot and hernias. Others, including heart defects, neural tube defects, and down syndrome, can cause lifelong impacts. Congenital disorders are one of the main causes of the global burden of disease, and low- and middle-income countries are disproportionately affected. These areas are also less likely to have facilities to treat reversible conditions such as clubfoot, leading to more pronounced and long-lasting effects. Approximately 50% of congenital disorders cannot be linked to a specific cause. However, known causes include single gene defects, chromosomal disorders, multifactorial inheritance, environmental teratogens and micronutrient deficiencies. Genetic causes can be traced to inherited genes or from mutations. Consanguinity – when parents are related by blood – increases the risk of congenital anomalies and nearly doubles the risk of neonatal and early childhood death, intellectual disability and other health conditions. Advanced maternal age also increases the risk of chromosomal abnormalities, including Down syndrome. Some diseases are known to cause increases in rates of congenital disorders including Zika virus, syphilis and rubella. Other anomalies, such as cystic fibrosis and haemophilia C, are more prevalent in specific ethnic communities. The vast majority (94%) of congenital disorders occur in low- and middle-income countries. Possible causes include lack of screening and prenatal care, insufficient access to nutritious foods for pregnant women, use or contact with alcohol or tobacco, and increased exposure to infection or environmental contaminants. Some congenital disorders can be prevented through screening, vaccination, fortification of staple foods with nutrients such as folic acid and iodine, and adequate antenatal care, among other methods.