Around 303,000 newborns die within 4 weeks of birth every year, worldwide, due to congenital anomalies and although 50% of all congenital anomalies are not linked to a specific cause, there are known genetic,  environmental and other causes or risk factors.

Congenital anomalies are important causes of infant and childhood deaths, chronic illness and disability. Also known as birth defects, congenital disorders or congenital malformations. Congenital anomalies can be defined as structural or functional anomalies (for example, metabolic disorders) that occur during intrauterine life and can be identified prenatally, at birth, or sometimes may only be detected later in infancy, such as hearing defects.

In simple terms, congenital refers to the existence at or before birth. An estimated 303,000 newborns die within 4 weeks of birth every year, worldwide, due to congenital anomalies. Although approximately 50 per cent of all congenital anomalies cannot be linked to a
specific cause, there are some known genetic, environmental and other causes or risk factors.

Genes play an important role in many congenital anomalies. This might be through inherited genes that code for an anomaly, or  resulting from sudden changes in genes known as mutations. Consanguinity (when parents are related by blood) also increases the prevalence of rare genetic congenital anomalies and nearly doubles the risk for neonatal and childhood death, intellectual disability and other anomalies.

Some ethnic communities (such as Ashkenazi Jews or Finns) have a comparatively high prevalence of rare genetic mutations such as Cystic Fibrosis and Haemophilia C. Low-income may be an indirect determinant of congenital anomalies, with a higher frequency among resource-constrained families and countries. It is estimated that about 94 per cent of severe congenital anomalies occur in low- and middle-income countries.

An indirect determinant, this higher risk relates to a possible lack of access to sufficient, nutritious foods by pregnant women, an  increased exposure to agents or factors such as infection and alcohol, or poorer access to healthcare and screening. Factors often associated with lower-income may induce or increase the incidence of abnormal prenatal development. Maternal age is also a risk factor for abnormal intrauterine fetal development. Advanced maternal age increases the risk of chromosomal abnormalities, including
Down syndrome.

Maternal exposure to certain pesticides and other chemicals, as well as certain medications, alcohol, tobacco and radiation during pregnancy, may increase the risk of having a fetus or neonate affected by congenital anomalies. Working or living near, or in, waste sites, smelters or mines may also be a risk factor, particularly if the mother is exposed to other environmental risk factors or nutritional deficiencies.

Maternal infections such as syphilis and rubella are a significant cause of congenital anomalies in low- and middle-income countries.
Maternal folate insufficiency increases the risk of having a baby with a neural tube defect while excessive vitamin A intake may affect the normal development of an embryo or fetus.