Teratology最新文献

Background: While overall infant mortality rates (IMR) have declined over the past several decades, birth defects have remained the leading cause of infant death in the United States. To illustrate how this leading cause of infant mortality impacts subgroups within the US population a descriptive analysis of the contribution of birth defects to infant mortality at the national and state level was conducted.

Methods: Descriptive analyses of birth defects-specific IMRs and proportionate infant mortality due to birth defects were conducted for the US using 1999 mortality data from the National Center for Health Statistics. In 1999, the change to ICD-10 impacted how cause-specific mortality rates were coded. Aggregated 1995-1998 state- birth defects infant death statistics were used for state comparisons.

Results: In 1999, birth defects accounted for nearly 1 in 5 infant deaths in the US. Variation in birth defects-specific IMRs were observed by maternal race with black infants having the highest rates when compared with other race groups. However, among black infants prematurity/low birthweight was the leading cause of death, followed by birth defects. There is substantial variation in state-specific birth defects IMRs and the state-specific proportion of infant deaths due to birth defects.

Conclusions: Birth defects remain the leading cause of infant death in the United States, despite the changes that resulted in 1999 from an update in the coding of cause of death from ICD-9 to ICD-10. While birth defects-specific IMRs provide an overall picture of fatal birth defects and a gauge of the impact of life-threatening anomalies, they represent only a fraction of the impact of birth defects, missing those who survive past infancy and those birth defects related losses in the antepartum period. Expansion and support of effective birth defects monitoring systems in each state that include the full spectrum of perinatal outcomes must be a priority. However, paralleling these efforts, analyses of this leading cause of infant mortality provide critical insight into perinatal health and should continue, with appropriate adjustments for the 1999 classification changes.

Background: The majority of U.S. birth defects surveillance programs do not include elective terminations before 20 weeks gestation among the pregnancy outcomes covered. To assess the impact of defects among elective terminations before 20 weeks gestation, data from a birth defects registry that does include terminations before 20 weeks gestation were analyzed.

Methods: Using information from the Texas Birth Defects Registry, the number of cases and rate of 49 conditions were analyzed in two ways: excluding defects detected among elective pregnancy terminations before 20 weeks gestation, and including defects among terminations before 20 weeks.

Results: By including defects detected among elective terminations before 20 weeks, the number of cases increased by five percent or greater for nine conditions: anencephaly (29%); spina bifida without anencephaly (13%); encephalocele (21%); Patau syndrome (19%); Edwards syndrome (11%); Down syndrome (6%); omphalocele (15%); gastroschisis (5%); and anophthalmia (7%). There was no impact for 27 conditions, for which there were no cases detected among elective terminations before 20 weeks. The greatest impact was observed for anencephaly; the rate of anencephaly increased from 2.76 to 3.56 per 10,000 live births when defects among elective terminations before 20 weeks were included.

Conclusions: Excluding defects among elective terminations before 20 weeks results in counts and rates that are somewhat incomplete, especially for conditions that are more commonly detected and electively terminated before 20 weeks. The impact varies by condition.

Background: Approximately 10% of birth defects result from chromosomal abnormalities. This study investigated the pregnancy outcome distribution of autosomal abnormalities and impact of prenatal diagnosis on autosomal abnormalities.

Methods: Data were obtained from a population-based birth defects registry and included all autosomal abnormalities delivered in Hawaii during 1986-1999.

Results: There were 1,015 autosomal abnormality cases, consisting of 523 (52%) live births, 38 (4%) late fetal deaths, 187 (18%) early fetal deaths, 265 (26%) elective terminations, and 2 unknown pregnancy outcome. Live births comprised the majority of translocations (81%), inversions (93%), and deletions (84%) but a smaller proportion of trisomies (42%). Autosomal abnormalities were prenatally diagnosed in 489 (48%) of the cases, of which 243 (50%) were subsequently electively terminated. By type of autosomal abnormality, prenatal diagnosis rates were trisomy (44%), translocation (68%), inversion (91%), deletion (29%), and subsequent elective termination rates were trisomy (73%), translocation (11%), inversion (4%), deletion (50%). The prenatal diagnosis rate was higher for maternal age 35 years or greater than for maternal age less than 35 years (relative risk (RR) 1.8, 95% confidence interval (CI) 1.6-2.0), as was the elective termination rate (RR 1.3, 95% CI 1.1-1.6). The prenatal diagnosis rate was higher in 1993-1999 than in 1986-1992 (RR 1.2, 95% CI 1.1-1.4), although there was no statistically significant difference between the two time periods for subsequent elective termination rate (RR 0.9, 95% CI 0.8-1.1).

Conclusions: Pregnancy outcome distribution, prenatal diagnosis rates, and subsequent elective terminations rates vary by type of autosomal abnormality.

Background: The Utah Birth Defect Network, a statewide surveillance program based in the Utah Department of Health, monitors the occurrence of all neural tube defects (NTDs). Retrospectively and prospectively population-based data was utilized to assess the trend in prevalence for NTDs in Utah from 1985-2000.

Methods: The Utah Birth Defect Network (UBDN) has prospectively identified NTDs in Utah since 1994. NTD cases, including meningomyelocele, meningocele, anencephaly (including exencephaly), encephalocele and craniorachischisis, born to women who are residents of Utah at delivery are reviewed by a pediatric geneticist. All NTDs occurring from 1985-1993 were ascertained retrospectively and documented to be a case. NTDs from all pregnancy outcomes are included (live births, stillbirths and pregnancy terminations) during the entire study period.

Results: NTDs in Utah have decreased significantly between 1985-2000 and remain at the lowest prevalence over the last three of those years. The most significant decrease was seen from 1993-2000. The downward trend was demonstrable for anencephaly and meningomyelocele but not for encephalocele. The proportion of NTDs diagnosed prenatally, as well as those pregnancies terminated after prenatal diagnosis have remained constant, without any evidence of an increasing trend since 1990. However, the proportion of pregnancy terminations occurring prior to twenty weeks gestation has increased significantly since 1990.

Conclusions: The reason for the observed decrease is not known but is likely the result of simultaneous prevention activities locally and nationally, the Utah population's propensity for vitamin and supplement consumption, and recent food fortification. The Centers for Disease Control and Prevention recommended in 1992 that all women in their childbearing years take folic acid daily. The Utah Folic Acid Educational Campaign targeted all women of childbearing years beginning in 1996 with this message. Additionally, fortification of grains was voluntary from 1996, became mandatory in 1998 at which point NTD prevalence declined to its lowest level. These factors may have collectively contributed to the reduction observed in NTD prevalence within Utah, demonstrating the positive impact of an important public health endeavor.