Congenital anomalies can be defined as structural or functional anomalies that occur during intrauterine life. Also called birth defects, congenital disorders, 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 anomaly, 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 anomalies 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 anomalies 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 anomalies 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 anomalies 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 anomalies 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 anomalies 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.
Around the world each year, an estimated 295 000 newborns die before reaching 4 weeks of age due to congenital anomalies and associated complications.
Congenital anomalies can contribute to life-long disability and health conditions. Over 50% of disability-adjusted life years (DALYs) lost each year due to congenital anomalies could be prevented with prompt surgery or other treatment. For example, 100 000 babies are born each year with clubfoot, which can be easily corrected. Left untreated, however, this condition can cause severe and permanent disability.
Many congenital anomalies result in social stigma and discrimination, which can lead to embarrassment, isolation and other reductions in community interaction. These conditions also have a high economic cost; long-term disability creates significant impact on individuals, families, health care systems and societies. These effects are amplified in low- and middle-income countries where lack of accessibility and availability of support services may make living with an impairment more difficult.