Abnormal structures or functions of an infant due to heredity, prenatal environment, or the birth process.
Malformations, malfunctions, and other congenital disorders that appear in newborns, including genetic disorders and chromosomal abnormalities as well as problems resulting from other causes, such as exposure to radiation, drugs, disease, or injury during pregnancy or childbirth. Some defects are so lethal that the fetus fails to develop and a spontaneous abortion (miscarriage) occurs, sometimes so early in pregnancy that the woman does not even know she is pregnant. Other defects result in babies dying shortly after birth, such as those with anencephaly. Of those babies who survive, perhaps 5 to 9 percent have some sort of birth defect; the percentage may be higher because some congenital disorders (such as Huntington’s chorea) appear only later in life. Some birth defects can now be spotted during genetic screening early in pregnancy, giving the parents the option of having a selective abortion; in a few special situations, repairing the defect through in utero surgery; or preparing to raise a child with special needs. Physicians who specialize in birth defects are called teratologists, from the Greek word teras, meaning “monster.”
Physical problems or abnormalities present in a baby at birth. Birth defects, also known as congenital anomalies, can affect the baby’s appearance or how his or her brain or other organs function. The cause of most birth defects is unknown. However, some birth defects, called genetic disorders, are inherited from the baby’s parents; others may be acquired prenatally, for example, when a woman contracts a specific infection (such as rubella, toxoplasmosis, cytomegalovirus, or syphilis), or if the fetus is exposed to a chemical substance (such as drugs or alcohol) during pregnancy. Birth defects may also be acquired during labor and delivery.
A defect which is present at birth. A birth defect may be due to inheritance (hereditary), or due to some other cause, such as injury to the mother or infection.
A congenital anomaly. Birth defects are a leading cause of infant mortality in the U.S. and most developed countries. Each year in the U.S. about 150,000 babies are born with serious birth defects. Known causes include human teratogens, chromosomal defects, and single-gene defects. The cause is unknown in about two thirds of the cases.
Congenital abnormalities, also known as birth defects, encompass a wide range of conditions that are either evident at birth or detectable during early infancy. These abnormalities can range from minor variations like birthmarks to severe disorders such as spina bifida, which involves the incomplete closure of the spinal column. Birth defects may arise due to various factors, although in many cases, no specific cause can be identified.
Certain individuals are born with an atypical number of chromosomes, deviating from the usual 23 pairs of threadlike structures called chromosomes that contain genetic information necessary for normal development. Down syndrome, characterized by the presence of an additional copy of one of the chromosomes, is among the most prevalent chromosomal abnormalities.
Inherited genetic defects can contribute to the occurrence of certain abnormalities present at birth. Examples of such defects include albinism, characterized by a deficiency of normal pigmentation in the skin, hair, and eyes, as well as achondroplasia, a condition resulting in abnormally short stature.
Certain medications and chemicals, known as teratogens, possess the potential to harm the developing fetus if taken or exposed to by the mother during early pregnancy. Examples of teratogenic drugs include thalidomide, which is now rarely prescribed, and isotretinoin, commonly used for severe acne treatment. Additionally, alcohol consumption during pregnancy can adversely affect the development of the brain and facial features of the fetus. It is essential to exercise caution and consult healthcare professionals regarding the use of drugs and exposure to substances during pregnancy to minimize potential risks to the unborn child.
Exposing the embryo to radiation during its early stage of development, such as when a woman undergoes an X-ray procedure before realizing she is pregnant, can lead to the occurrence of abnormalities. It is crucial to be aware of the potential risks associated with radiation exposure during pregnancy and take necessary precautions, including informing healthcare providers about the possibility of pregnancy before undergoing any diagnostic procedures involving radiation. This helps minimize the potential harm to the developing embryo.
If a woman contracts certain infections during pregnancy, there is a possibility that they may result in birth defects. For instance, rubella, also known as German measles, when contracted in the early stages of pregnancy, can cause fetal abnormalities such as deafness, cataracts (clouding of the lens of the eye), and heart disease. Similarly, toxoplasmosis, an infection caused by a parasite found in cat feces, can be transmitted to the fetus and lead to damage in the eyes, liver, and other organs. It is crucial for pregnant women to take necessary precautions to prevent exposure to such infections and seek appropriate medical care to safeguard the health and well-being of both themselves and their unborn child.
Abnormalities during embryonic development can have detrimental effects on the brain and spinal cord, leading to conditions such as spina bifida, characterized by incomplete closure of the spinal column, and hydrocephalus, which involves an accumulation of fluid in the brain. Congenital heart disorders refer to structural abnormalities in the heart that can disrupt normal blood flow. Cleft lip and palate result from incomplete fusion of the facial and palatal structures during fetal development, leading to a separation in the upper lip or palate. These conditions highlight the intricate nature of embryonic development and the potential impact of abnormalities on various organ systems.
Ultrasound scanning and blood tests conducted during pregnancy can help identify women who are at a higher risk of having a baby with a birth defect. Subsequent diagnostic tests, such as chorionic villus sampling, amniocentesis, or fetoscopy, may be performed to gather more detailed information and assess the health of the developing fetus. These additional tests provide valuable insights and assist healthcare professionals in making informed decisions regarding the management of the pregnancy and any potential interventions that may be necessary.
Certain birth defects can be prevented or their risks minimized through proactive measures. For instance, immunization against rubella before pregnancy can help prevent the risk of rubella infection during pregnancy, which can cause fetal abnormalities. Additionally, avoiding exposure to teratogens (substances known to cause birth defects) during pregnancy plays a vital role in reducing the potential risks to the developing fetus. Taking preventive actions and making informed choices can greatly contribute to promoting a healthier pregnancy and minimizing the occurrence of birth defects.