Birth Defects

Birth defects (or congenital disorders, as many people prefer to call them) come in many varieties. Some birth defects are serious, and result in lifelong difficulties for those who are born with them. Others are easily manageable, or even curable. Some birth defects are hereditary, running in families for generations, sometimes via recessive genes; others result from random genetic mutation. And sadly, some types of birth defect are caused by irresponsible behavior on the part of the mother.

Genetic Birth Defects vs Congenital Problems Caused by External Factors

Not all birth defects are caused by genetic abnormalities—some are caused by external factors such as maternal injury, maternal drug or alcohol abuse, etc.—and not all genetic abnormalities are heritable. While many of them (such as Leber’s hereditary optic neuropathy, for example) tend to run in families, many others (such as achondroplasia or fetal alcohol syndrome) are the result of random mutation or external factors.


Achondroplasia is a genetic condition associated with dwarfism (short stature, shortened limbs and digits, and enlarged head). This condition tends to be the result of genetic mutation (sometimes associated with advanced paternal age), although it can also occur when both parents carry the gene recessively.

Down’s Syndrome

Down’s Syndrome is caused by the failure of the 21st chromosome to separate while an egg or sperm cell is developing; that sperm or egg will therefore carry an extra copy of this chromosome, and the resulting embryo (and baby) will have 47 chromosomes, rather than the normal 46. The egg is the cause in 88 percent of cases. Adults with Down’s Syndrome typically have the mental ability of a seven- or eight-year-old child.

Amelia (Missing Limbs)

Children born with missing hands, arms, legs, or feet are said to suffer amelia. Amelia may be genetic in some cases, but the most common cause of this birth defect is interruption or prevention of limb formation between the 24th and 36th day of pregnancy (infection may be one reason this happens). There is also a very rare genetic disorder known as tetra-amelia syndrome,; children suffering from this condition are born without all four limbs. Tetra-amelia syndrome tends to be accompanied by a variety of other congenital medical problems—including malformations of the head, heart, skeleton, and lung—and babies born with this condition are often stillborn or die shortly after birth.


Congenital blindness can result from a number of causes, including:

  1. Bardet–Biedl syndrome (which is also associated with speech disorders)
  2. Congenital Rubella Syndrome, which may also cause deafness and intellectual disability, and can occur if the mother contracts rubella during the first trimester of her pregnancy
  3. Retinopathy of Prematurity (also known as Terry Syndrome), which is believed to be caused by the disorganized growth of the retinal blood vessels.
  4. Leber’s hereditary optic neuropathy, condition inherited from the mother, usually by male children, characterized by a degeneration of retinal ganglion cells, leading to a loss of central vision.


Congenital deafness can be caused by any of the following:

  1. Usher Syndrome: a genetic disorder also associated with vision loss
  2. Waardenburg syndrome: a genetic disease characterized by varying degrees of deafness
  3. Alport Syndome: another genetic disorder, which tends to cause hearing loss and kidney disease

Spinal Bifida

This condition is caused by an incomplete closing of the embryo’s neural tube—the precursor to the central nervous system of a fully developed child. Symptoms can include weakness and paralysis of the legs, abnormal movement of the eyes, pressure sores, and orthopedic conditions such as club foot. The likelihood of spinal bifida—which occurs in one out of every 1,000 live births—can be reduced up to 70 percent if the mother takes folic acid supplements on a daily basis prior to conception.

Fetal Alcohol Syndrome

Fetal Alcohol Syndrome (FAS) occurs when alcohol gets past the barrier created by the placenta and affects the developing fetus. Alcohol exposure in sufficient quantities — such as can occur with regular and/or heavy drinking — can stunt growth and cause serious harm to a developing baby’s brain and central nervous system. FAS is one of the leading causes of intellectual disability worldwide, and children born with this disorder also have a distinctive physical appearance. Perhaps the most tragic aspect of Fetal Alcohol Syndrome is its preventability—it differs from other types of birth defects in that all a pregnant woman needs to do to avoid inflicting this condition on her child is abstain from alcohol for nine months; this should be easy, especially compared to the myriad other lifestyle adjustments that must be made to accommodate pregnancy.

Congenital Hydrocephalus

Hydrocephalus is more commonly known as “water on the brain,” a slightly misleading description of a condition in which cerebrospinal fluid accumulates in various cavities in the brain. This creates pressure inside the skull and can cause tunnel vision and even enlargement of the head itself. The bones in the skull of a newborn have not yet bonded firmly, and this condition, if not treated properly, can result in permanent and severe physical deformity.

Cleft Lip

A cleft lip, also known as a harelip, occurs in one out of every 700 births, and results from abnormal development during pregnancy. A cleft lip appears as a gap in the child’s upper lip, which severely disfigures the face and can cause the infant to have difficulty feeding. A child with an uncorrected cleft lip may have speech difficulties, and many such children develop psychological problems stemming from the difficulty they face interacting with their peers. A cleft lip can be genetic, or it can be caused by maternal exposure to any number of environmental toxins.

  • Amniotic Band Syndrome >

    The term amniotic band syndrome (or amniotic band constriction) describes a congenital deformity caused by the entanglement of a fetus in a web of fibrous tissue strands extending from the lining of the amnion, the innermost layer of the amniotic sac in which the fetus grows into a baby. In some cases these strands of […]

  • Amniotic Fluid Embolism >

    Amniotic fluid embolism is an unpredictable, unpreventable and untreatable obstetric condition with a mortality rate of 80%. Learn more about this devastating condition that happens in approximately one out of every 21,000 pregnancies.

  • Birth Complications >

    Complications during birth are more common than complications during a woman’s pregnancy. There are so many things that can go wrong during these last moments of expectancy. Learn about the different complications that arise at birth, what to expect if you encounter some of these complications, and what to expect from your health care provider. […]

  • Breech Birth >

    In approximately 96 percent of all births, the fetus assumes a head-down position around the 36th week of pregnancy, and the baby is born head first. In some cases, however, the fetus fails to assume this position, and when labor begins the baby is still in a feet-down or bottom-down position. This is called breech […]

  • Erb’s Palsy >

    Erb’s Palsy is usually caused by an injury suffered at birth during a vaginal delivery when the head and shoulders of a baby are pulled in opposite directions as he or she is delivered through the birth canal. This can cause a weakness in the upper arm and rotation of the lower arm, generally on one side of the body. Complications can include loss of function of the affected nerves, and paralysis of the arm or arm weakness.

  • Gestational Trophoblastic Disease >

    The term gestational trophoblastic disease (GTD) refers to certain types of tumors that can occur during pregnancy. These tumors begin in the cells that under normal circumstances would develop into the placenta (the organ that develops during pregnancy and provides the growing fetus with oxygen and nutrition), and they cause the placenta to develop abnormally.

  • Low Birth Weight >

    Sometimes babies are born with low birth weights, regardless if they’re born premature or full term. Find out the two main causes of this birth complication, as well as how to prevent and treat the problem.

  • Macrosomia >

    Macrosomia is a term used to describe a large newborn. Thankfully, this is not a life-threatening birth complication, however, many mothers suffer excessive tearing and recovery processes may be extended.

  • Neonatal Intensive Care Unit >

    While the overwhelming majority of pregnancies result in the birth of healthy babies without complications, childbirth is still an inherently risky process, and things can sometimes go wrong. Modern medicine has sharply reduced the rate of infant mortality in the developed world, but in some cases newborn babies need to be placed in a Neonatal […]

  • Postpartum Depression >

    Postpartum depression may or may not appear in women after giving birth. Learn about the symptoms and treatment options, plus much more.

  • PPROM and PROM (Premature Rupture of Membranes) >

    Before a baby is born, the water bag needs to break at some point. Maybe this happens at the very last second, in which case the doctor who is positioned to deliver the baby gets hit with a huge gush of water (as has happened to this author more than once!). Or more often the […]

  • Premature Birth >

    While exact figures are difficult to nail down, it is estimated that 15 million premature births occur worldwide each year. Premature birth (or preterm birth) is defined as any live birth that takes place prior to 37 weeks of gestation. In developed countries like the United States — where one out of every eight newborns […]

  • Umbilical Cord Abnormalities >

    Throughout pregnancy, the umbilical cord serves as the primary connection between mother and child. It provides the baby with oxygen and nourishment—it is, in a very literal sense, the baby’s lifeline. This means that if something goes wrong with the umbilical cord, it can sometimes become a medical emergency for which immediate medical attention must […]

  • Uterine Rupture >

    Uterine ruptures are very rare, yet they are a very serious birth complication that can be life-threatening to both mother and baby if not treated immediately. Find out what causes uterine ruptures, symptoms to watch for and who’s at risk.

Medical References:

    National Institute of Health, D (Jul 2009). "Molecular genetic analysis of Down syndrome.". Human genetics 126 (1): 195–214.Lana-Elola, E; Watson-Scales, SD; Fisher, EM; Tybulewicz, VL (Sep 2011). "Down syndrome: searching for the genetic culprits.". Disease models & mechanisms 4 (5): 586–95Wynn J, King TM, Gambello MJ, Waller DK, Hecht JT (2007). "Mortality in achondroplasia study: A 42-year follow-up". Am. J. Med. Genet. A 143 (21): 2502–11.Abel, E.L., & Sokol, R.J. (1987). Incidence of fetal alcohol syndrome and economic impact of FAS-related anomalies: Drug alcohol syndrome and economic impact of FAS-related anomalies. Drug and Alcohol Dependency, 19(1), 51–70
[Page updated June 2017]