A birth defect may be a structural defect, a deficiency of function, or a disease present at birth. Some birth defects are genetic—inherited abnormalities such as Tay-Sachs disease (a fatal disease that generally affects children of Eastern European Jewish ancestry), or chromosomal irregularities such as Down's syndrome. Other birth defects result from environmental factors—infections during pregnancy, such as rubella (German measles), or drugs used by the pregnant woman. Although the specific causes of many birth defects are unknown, scientists think that many result from a combination of genetic and environmental factors. Though many birth defects are impossible to prevent, some can be prevented, such as
TABLE 5.1
Infant, neonatal, and postneonatal mortality rates, by race and Hispanic origin of mother, 1993–2001
[Data are based on linked birth and death certificates for infants]
| Race and Hispanic origin of mother | 19831 | 19851 | 19901 | 19952 | 19982 | 19992 | 20002 | 20012 |
| Postneonatal3 deaths per 1,000 live births | ||||||||
| All mothers | 3.8 | 3.6 | 3.2 | 2.6 | 2.4 | 2.3 | 2.3 | 2.3 |
| White | 3.2 | 3.1 | 2.7 | 2.2 | 2.0 | 1.9 | 1.9 | 1.9 |
| Black or African American | 6.7 | 6.3 | 5.9 | 5.0 | 4.4 | 4.5 | 4.3 | 4.4 |
| American Indian or Alaska Native | 7.7 | 7.0 | 7.0 | 5.1 | 4.4 | 4.3 | 3.9 | 5.4 |
| Asian or Pacific Islander | 3.1 | 2.9 | 2.7 | 1.9 | 1.7 | 1.7 | 1.4 | 1.6 |
| Chinese | 4.0 | *2.5 | *2.0 | *1.5 | *1.3 | *1.2 | *1.0 | *1.3 |
| Japanese | * | *2.9 | * | * | * | * | * | * |
| Filipino | *2.8 | 2.7 | 2.5 | 2.2 | 1.6 | 1.9 | 1.6 | *1.5 |
| Hawaiian | *4.2 | *4.3 | *3.8 | * | * | * | * | *3.7 |
| Other Asian or Pacific Islander | 3.0 | 3.0 | 3.0 | 1.9 | 1.8 | 1.8 | 1.4 | 1.6 |
| Hispanic or Latino4, 5 | 3.3 | 3.2 | 2.7 | 2.1 | 1.9 | 1.8 | 1.8 | 1.8 |
| Mexican | 3.2 | 3.2 | 2.7 | 2.1 | 1.9 | 1.8 | 1.8 | 1.7 |
| Puerto Rican | 4.2 | 3.5 | 3.0 | 2.8 | 2.6 | 2.4 | 2.4 | 2.5 |
| Cuban | *2.5 | *2.3 | *1.9 | *1.7 | * | * | * | *1.7 |
| Central and South American | 2.6 | 2.4 | 2.4 | 1.9 | 1.7 | 1.4 | 1.4 | 1.6 |
| Other and unknown Hispanic or Latino | 4.2 | 3.9 | 3.0 | 2.6 | 2.0 | 2.5 | 2.3 | 2.1 |
| Not Hispanic or Latino: | ||||||||
| White5 | 3.2 | 3.0 | 2.7 | 2.2 | 2.0 | 1.9 | 1.9 | 1.9 |
| Black or African American5 | 7.0 | 6.4 | 5.9 | 5.0 | 4.5 | 4.6 | 4.4 | 4.5 |
| *Estimates are considered unreliable. Rates preceded by an asterisk are based on fewer than 50 events. Rates not shown are based on fewer than 20 events. | ||||||||
| 1Rates based on unweighted birth cohort data. | ||||||||
| 2Rates based on a period file using weighted data. | ||||||||
| 3Infant (under 1 year of age), neonatal (under 28 days), and postneonatal (28 days–11 months). | ||||||||
| 4Persons of Hispanic origin may be of any race. | ||||||||
| 5Prior to 1995, data shown only for states with an Hispanic-origin item on their birth certificates. | ||||||||
| Notes: The race groups white, black, American Indian or Alaska Native, and Asian or Pacific Islander include persons of Hispanic and non-Hispanic origin. | ||||||||
| SOURCE: Adapted from "Table 19. Infant, Neonatal, and Postneonatal Mortality Rates, according to Detailed Race and Hispanic Origin of Mother: United States, Selected Years 1983–2001," in Health, United States, 2003, Centers for Disease Control and Prevention, National Center for Health Statistics, Hyattsville, MD, 2003 | ||||||||
those caused by maternal alcohol and drug consumption during pregnancy.
Two birth defects that have been the subject of considerable ethical debate are neural tube defects (NTDs) and permanent disabilities coupled with operable but life-threatening factors. An example of the latter is Down's syndrome, a genetic abnormality that causes mental retardation and, frequently, malformations of the heart or kidneys.
Neural Tube Defects
Neural tube defects (NTDs) are abnormalities of the brain and spinal cord resulting from the failure of the neural tube to develop properly during early pregnancy. The neural tube is the embryonic nerve tissue that develops into the brain and the spinal cord. Every year about 4,000 unborn children are affected with NTDs. Of these, approximately 2,500 cases involve infants born with the two most common NTDs—anencephaly and spina bifida.
ANENCEPHALY.
Anencephalic infants die before birth (in utero or stillborn) or shortly thereafter. The incidence of anencephaly dropped significantly from 1991 (0.018 percent) to 2002 (0.0095 percent) in the states where data were reported. The largest drop during that time period was from 1991 to 1992. Since then, the general trend has been downward. (See Table 5.5.)
Issues of brain death and organ donation sometimes surround anencephalic infants. One case that gained national attention was that of Theresa Ann Campo in 1992. Prior to their daughter's birth, Theresa's parents (a Florida couple) discovered through prenatal testing that their baby would be born without a fully developed brain. They decided to carry the fetus to term and donate her organs for transplantation. When baby Theresa was born, her parents asked for her to be declared brain dead. However, Theresa's brain stem was still functioning, so the court ruled against the parents' decision. Baby Theresa died ten days later and her organs were not usable for transplant, having deteriorated as a result of oxygen deprivation.
Some physicians and ethicists agree that even if anencephalic babies have a brain stem, they should be considered brain dead. Lacking a functioning higher brain, these babies can feel nothing; they have no consciousness. Others fear that declaring anencephalic babies dead could be the start of a "slippery slope" which might eventually include babies with other birth defects, such as spina bifida, in the same category. Spina bifida defects range from mild to severe. Other people are concerned that anencephalic babies may be kept alive for the purpose of harvesting their organs for transplant at a later date.
TABLE 5.2
Infant deaths and infant mortality rates, by age, race, and Hispanic origin, final 2001 and preliminary 2002
[Data are based on the continuous file of records received from the states. Rates per 1,000 live births. Figures for 2002 are based on weighted data rounded to the nearest individual, so categories may not add to totals. Rates for Hispanic origin should be interpreted with caution because of the inconsistencies between reporting Hispanic origin on birth and death certificates.]
| 2002 | 2001 | |||
| Age and race/Hispanic origin | Number | Rate | Number | Rate |
| All races1 | ||||
| Under 1 year | 27,977 | 7.0 | 27,568 | 6.8 |
| Under 28 days | 18,749 | 4.7 | 18,265 | 4.5 |
| 28 days–11 months | 9,229 | 2.3 | 9,303 | 2.3 |
| Total white2 | ||||
| Under 1 year | 18,390 | 5.8 | 17,955 | 5.7 |
| Under 28 days | 12,419 | 3.9 | 12,013 | 3.8 |
| 28 days–11 months | 5,971 | 1.9 | 5,942 | 1.9 |
| Non-Hispanic white | ||||
| Under 1 year | 13,492 | 5.9 | 13,311 | 5.7 |
| Under 28 days | 9,064 | 3.9 | 8,888 | 3.8 |
| 28 days–11 months | 4,428 | 1.9 | 4,423 | 1.9 |
| Total black2 | ||||
| Under 1 year | 8,446 | 14.3 | 8,498 | 14.0 |
| Under 28 days | 5,580 | 9.4 | 5,585 | 9.2 |
| 28 days–11 months | 2,866 | 4.9 | 2,913 | 4.8 |
| Hispanic3 | ||||
| Under 1 year | 4,928 | 5.6 | 4,680 | 5.5 |
| Under 28 days | 3,345 | 3.8 | 3,112 | 3.7 |
| 28 days–11 months | 1,583 | 1.8 | 1,568 | 1.8 |
| 1Includes races other than white or black. | ||||
| 2Race and Hispanic origin are reported separately on both the birth and death certificates. Data for persons of Hispanic origin are included in the data for each race group, according to the reported race. | ||||
| 3Includes all persons of Hispanic origin of any race. | ||||
| Note: Data are subject to sampling and/or random variation. | ||||
| SOURCE: "Table 4. Infant Deaths and Infant Mortality Rates, by Age and Race and Hispanic Origin: United States, Final 2001 and Preliminary 2002," in Deaths: Preliminary Data for 2002, National Vital Statistics Reports, National Center for Health Statistics, Hyattsville, MD, vol. 52, no. 13, February 11, 2004 | ||||
SPINA BIFIDA.
Spina bifida, which literally means "divided spine," is caused by the failure of the vertebrae (backbone) to completely cover the spinal cord early in fetal development, leaving the spinal cord exposed. Depending upon the amount of nerve tissue exposed, spina bifida defects range from minor developmental disabilities to paralysis.
Before the advent of antibiotics in the 1950s, most babies with severe spina bifida died soon after birth. With antibiotics and numerous medical advances, some of these newborns can be saved.
The treatment of newborns with spina bifida can pose serious ethical problems. Should an infant with a milder form of the disease be treated actively while another with severe defects is left untreated? In severe cases, should the newborn be sedated and not be given nutrition and hydration until death occurs? Or should this seriously disabled infant be cared for while suffering from bladder and bowel malfunctions, infections, and paralysis? What if infants who have been left to die unexpectedly survive? Would they be more disabled than if they had been treated right away?
The development of fetal surgery to correct spina bifida before birth added another dimension to the debate. Physicians realized that they could prevent some of the damage caused by amniotic fluid bathing the cord and tissues pressing on the cord by covering the exposed spinal cord during pregnancy. In 1994 several doctors attempted a surgery to do this by making a tiny incision in the mother's uterus and performing the procedure with the help of an endoscope (viewing instrument). After several unsuccessful attempts over three years, in 1997 surgeons tried an approach that proved successful: they opened the uterus and performed the corrective surgery. There are risks for both the mother and the fetus during and after fetal surgery, but techniques have improved since the first successful surgery of this type was performed. The National Institute of Child Health and Development predicts that by the year 2020, routine diagnosis and treatment of congenital malformations by means of fetal surgery will be standard therapy for most disabling malformations that are currently treated in young infants.
In the treatment of spina bifida with fetal surgery, the results have been promising thus far: most of the babies operated on in utero as fetuses have shown few physical or cognitive symptoms of spina bifida. Further tests will be necessary when these children reach school age in order to help assess their progress. The surgery does, however, raise ethical questions—it is not performed to save the infant's life, as in most other fetal surgeries, but to improve quality of life. Parents must weigh the potential failure of the operation and death of the child against the possible benefits.
Scientists now know that daily consumption of 0.4 mg of the B vitamin folic acid by women before and during the first trimester (three months) of pregnancy greatly reduces the risk of spina bifida and other birth defects. To comply with a mandate from the U.S. Food and Drug Administration (FDA), as of January 1998 all enriched cereal grain products must be fortified with folic acid.
In the United States the rates of spina bifida have been declining since 1960 and, though there was a slight increase in the mid-1990s, the rates decreased from nearly 0.025 percent in 1991 to 0.020 percent in 2002 (note that not all states participated in reporting spina bifida cases). Table 5.6 shows case rates per 100,000 births from 1991 to 2002. The decline is an early indicator of successful efforts to prevent this defect by increasing folic acid consumption among women of childbearing age.
Down's Syndrome
Down's syndrome is a birth defect caused by chromosomal irregularities. Instead of the normal 46 chromosomes,
TABLE 5.3
Deaths and life expectancy at birth, by race and sex and infant deaths and mortality rates, by race, final 2001 and preliminary 2002
| All races1 | White | Black | ||||
| Measure and sex | 2002 | 2001 | 2002 | 2001 | 2002 | 2001 |
| All deaths | 2,447,864 | 2,416,425 | 2,107,730 | 2,079,691 | 289,431 | 287,709 |
| Age-adjusted death rate2 | 846.8 | 854.5 | 831.0 | 836.5 | 1,081.2 | 1,101.2 |
| Male | 1,015.3 | 1,029.1 | 995.1 | 1,006.1 | 1,338.4 | 1,375.0 |
| Female | 716.7 | 721.8 | 703.2 | 706.7 | 900.4 | 912.5 |
| Life expectancy at birth3 | 77.4 | 77.2 | 77.8 | 77.7 | 72.5 | 72.2 |
| Male | 74.7 | 74.4 | 75.3 | 75.0 | 68.9 | 68.6 |
| Female | 79.9 | 79.8 | 80.3 | 80.2 | 75.7 | 75.5 |
| All infant deaths | 27,977 | 27,568 | 18,390 | 17,955 | 8,446 | 8,498 |
| Infant mortality rate4 | 7.0 | 6.8 | 5.8 | 5.7 | 14.3 | 14.0 |
| 1Includes races other than white and black. | ||||||
| 2Age-adjusted death rates are per 100,000 U.S. standard population, based on the year 2000 standard. | ||||||
| 3Life expectancy at birth stated in years. | ||||||
| 4Infant mortality rates are deaths under 1 year per 1,000 live births in specified group. | ||||||
| SOURCE: "Table A. Deaths, Age-Adjusted Death Rates, and Life Expectancy at Birth, by Race and Sex; and Infant Deaths and Mortality Rates, by Race: United States, Final 2001 and Preliminary 2002," in Deaths: Preliminary Data for 2002, National Vital Statistics Reports, National Center for Health Statistics, Hyattsville, MD, vol. 52, no. 13, February 11, 2004 | ||||||
Down's syndrome newborns have an extra copy of chromosome 21, giving them a total of 47 chromosomes. These children have varying degrees of mental retardation, and approximately 40 percent have congenital heart diseases.
The CDC estimates prevalence of Down's syndrome at birth as approximately 10 cases per 10,000 live births. The occurrence of this birth defect rises with increasing maternal age, with a marked increase seen in children of women over 35 years of age at the time of delivery.
In the past, babies born with Down's syndrome were usually institutionalized. Many died in infancy. Today, with the help of modern medical care, children with Down's syndrome are typically raised at home and attain adulthood, although their life expectancy is shorter than average (approximately 55 years). Except for the most severe heart defects, many other malformations accompanying Down's syndrome may be corrected by surgery. Depending on the degree of mental retardation, many persons with Down's syndrome are able to hold jobs and live independently.
Birth Defects Prevention Act of 1998
On April 21, 1998, President Bill Clinton signed into law the Birth Defects Prevention Act (PL 105-168), which authorized a nationwide network of birth defects research and prevention programs and called for a nationwide information clearinghouse on birth defects. The law initially appropriated $70 million for fiscal years (FY) 1998 and 1999. Congress appropriated $90 million for FY 2002. Dr. Jennifer L. Howse, president of the March of Dimes Birth Defects Foundation, noted, "This legislation will help us find the causes of major birth defects, devise new ways to help prevent them, and better apply what we already know."
The bill was first introduced in 1992 by Representatives Solomon Ortiz (D-TX) and Henry Bonilla (R-TX) and Senator Christopher Bond (R-MO) in response to the clusters of anencephalic newborns in Cameron County, Texas. The Texas Department of Health reported an anencephaly rate of 13 per 10,000 live births in Cameron County from 1986 to 1991, a rate four times greater than the national rate. From 1990 to 1991 the rate climbed to 19.7 per 10,000 births. The cause of the outbreak was never determined.
National Center on Birth Defects and Developmental Disabilities
The Children's Health Act of 2000 authorized expanded research and services for a variety of childhood health problems. In addition, it created the National Center on Birth Defects and Developmental Disabilities (NCBDDD) at the Centers for Disease Control and Prevention (CDC). Developmental disabilities are conditions that impair day-to-day functioning, such as difficulties with communication, learning, behavior, and motor skills. The Birth Defects and Developmental Disabilities Prevention Act of 2003 reauthorized the NCBDDD through 2007. The Center's FY 2003 appropriation was $98 million.
The NCBDDD works with state health departments, academic institutions, and other public health partners to monitor birth defects and developmental disabilities, as well as to support research to identify their causes or risk factors. In addition, the Center develops strategies and promotes programs to prevent birth defects and developmental disabilities.
The Cost of Continued Care
The CDC reported that in 1992 (the most recent information available) the estimated cost of cerebral
TABLE 5.4
10 leading causes of infant deaths and infant mortality rates, by race and Hispanic origin, preliminary 2002
[Data are based on a continuous file of records received from the states. Rates are per 100,000 live births. Figures are based on weighted data rounded to the nearest individual, so categories may not add to totals or subtotals. Rates for Hispanic origin should be interpreted with caution because of inconsistencies between reporting Hispanic origin on birth and death certificates.]
| Rank1 | Cause of death and age | Number | Rate |
| All races2 | |||
| … | All causes | 27,974 | 696.0 |
| 1 | Congenital malformations, deformations and chromosomal abnormalities | 5,655 | 140.7 |
| 2 | Disorders related to short gestation and low birth weight, not elsewhere classified | 4,598 | 114.4 |
| 3 | Sudden infant death syndrome | 2,035 | 50.6 |
| 4 | Newborn affected by maternal complications of pregnancy | 1,723 | 42.9 |
| 5 | Newborn affected by complications of placenta, cord and membranes | 1,017 | 25.3 |
| 6 | Respiratory distress of newborn | 958 | 23.8 |
| 7 | Accidents (unintentional injuries) | 893 | 22.2 |
| 8 | Bacterial sepsis of newborn | 734 | 18.3 |
| 9 | Diseases of the circulatory system | 649 | 16.1 |
| 10 | Intrauterine hypoxia and birth asphyxia | 578 | 14.4 |
| … | All other causes | 9,134 | 227.2 |
| Total white3 | |||
| … | All causes | 18,447 | 580.8 |
| 1 | Congenital malformations, deformations and chromosomal abnormalities | 4,384 | 138.0 |
| 2 | Disorders related to short gestation and low birth weight, not elsewhere classified | 2,573 | 81.0 |
| 3 | Sudden infant death syndrome | 1,343 | 42.3 |
| 4 | Newborn affected by maternal complications of pregnancy | 1,070 | 33.7 |
| 5 | Newborn affected by complications of placenta, cord and membranes | 672 | 21.2 |
| 6 | Respiratory distress of newborn | 598 | 18.8 |
| 7 | Accidents (unintentional injuries) | 558 | 17.6 |
| 8 | Bacterial sepsis of newborn | 485 | 15.3 |
| 9 | Diseases of the circulatory system | 426 | 13.4 |
| 10 | Intrauterine hypoxia and birth asphyxia | 411 | 12.9 |
| … | All other causes | 5,927 | 186.6 |
| Non-Hispanic white | |||
| … | All causes | 13,542 | 587.9 |
| 1 | Congenital malformations, deformations and chromosomal abnormalities | 3,110 | 135.0 |
| 2 | Disorders related to short gestation and low birth weight, not elsewhere classified | 1,811 | 78.6 |
| 3 | Sudden infant death syndrome | 1,112 | 48.3 |
| 4 | Newborn affected by maternal complications of pregnancy | 821 | 35.6 |
| 5 | Newborn affected by complications of placenta, cord and membranes | 493 | 21.4 |
| 6 | Respiratory distress of newborn | 446 | 19.4 |
| 7 | Accidents (unintentional injuries) | 437 | 19.0 |
| 8 | Bacterial sepsis of newborn | 361 | 15.7 |
| 9 | Diseases of the circulatory system | 320 | 13.9 |
| 10 | Intrauterine hypoxia and birth asphyxia | 311 | 13.5 |
| … | All other causes | 4,321 | 187.6 |
| Total black3 | |||
| … | All causes | 8,380 | 1,419.0 |
| 1 | Disorders related to short gestation and low birth weight, not elsewhere classified | 1,836 | 310.9 |
| 2 | Congenital malformations, deformations and chromosomal abnormalities | 1,023 | 173.2 |
| 3 | Sudden infant death syndrome | 603 | 102.1 |
| 4 | Newborn affected by maternal complications of pregnancy | 575 | 97.3 |
| 5 | Respiratory distress of newborn | 336 | 57.0 |
| 6 | Newborn affected by complications of placenta, cord and membranes | 315 | 53.3 |
| 7 | Accidents (unintentional injuries) | 303 | 51.4 |
| 8 | Bacterial sepsis of newborn | 231 | 39.1 |
| 9 | Diseases of the circulatory system | 189 | 32.1 |
| 10 | Intrauterine hypoxia and birth asphyxia | 147 | 24.8 |
| … | All other causes | 2,822 | 477.8 |
palsy and seventeen other birth defects was $8 billion ("Economic Costs of Birth Defects and Cerebral Palsy—United States, 1992," Morbidity and Mortality Weekly Report, vol. 44, no. 37, September 22, 1995). Costs ranged from $75,000 to $503,000 per child and covered medical, developmental, and special education services, as well as lost productivity resulting from the child's death or disability. However, these estimated amounts do not include the costs to the family of wages lost in caring for the children. Birth defects characterized by long-term disabilities, such as cerebral palsy, Down's syndrome, and spina bifida, cost the most. Moreover, these conditions accounted for the highest total lifetime costs.
Research examining selected developmental disabilities associated with major birth defects was reported by Pierre Decoufle, et al. ("Increased Risk for Developmental Disabilities in Children Who Have Major Birth Defects: A Population-Based Study," Pediatrics, vol. 108, no. 3, September 2001). The investigators linked data from two independent population-based surveillance systems to find out if major birth defects were associated with serious developmental disabilities.
TABLE 5.4
10 leading causes of infant deaths and infant mortality rates, by race and Hispanic origin, preliminary 2002
[Data are based on a continuous file of records received from the states. Rates are per 100,000 live births. Figures are based on weighted data rounded to the nearest individual, so categories may not add to totals or subtotals. Rates for Hispanic origin should be interpreted with caution because of inconsistencies between reporting Hispanic origin on birth and death certificates.]
| Rank1 | Cause of death and age | Number | Rate |
| Hispanic4 | |||
| … | All causes | 4,933 | 565.5 |
| 1 | Congenital malformations, deformations and chromosomal abnormalities | 1,269 | 145.5 |
| 2 | Disorders related to short gestation and low birth weight, not elsewhere classified | 769 | 88.1 |
| 3 | Newborn affected by maternal complications of pregnancy | 246 | 28.2 |
| 4 | Sudden infant death syndrome | 241 | 27.7 |
| 5 | Newborn affected by complications of placenta, cord and membranes | 186 | 21.3 |
| 6 | Respiratory distress of newborn | 156 | 17.9 |
| 7 | Accidents (unintentional injuries) | 128 | 14.6 |
| 8 | Bacterial sepsis of newborn | 126 | 14.5 |
| 9 | Diseases of the circulatory system | 106 | 12.1 |
| 10 | Intrauterine hypoxia and birth asphyxia | 98 | 11.2 |
| … | All other causes | 1,610 | 184.6 |
| … Category not applicable. | |||
| 1Rank based on number of deaths. | |||
| 2Includes races other than white and black. | |||
| 3Race and Hispanic origin are reported separately on both the birth and death certificate. Data for persons of Hispanic origin are included in the data for each race group, according to the decedent's reported race. | |||
| 4Includes all persons of Hispanic origin of any race. | |||
| Note: Data are subject to sampling and/or random variation. | |||
| SOURCE: "Table 8. Infant Deaths and Infant Mortality Rates for the 10 Leading Causes of Infant Death, by Race and Hispanic Origin: United States, Preliminary 2002," in Deaths: Preliminary Data for 2002, National Vital Statistics Reports, National Center for Health Statistics, Hyattsville, MD, vol. 52, no. 13, February 11, 2004 | |||
When compared with children who had no major birth defects, the prevalence of developmental disabilities among children with major birth defects was extremely high. The researchers observed that conditions such as mental retardation, cerebral palsy, epilepsy, autism, profound hearing loss, and legal blindness "prove costly in terms of special education services, medical and supportive care, demands on caregivers, and economic loss to society." They concluded, "Our data suggest that birth defects pose a greater burden on society than previously recognized."
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