Frequency of Prenatal Diagnosis of Birth Defects in Houston, Galveston and the Lower Rio Grande Valley, Texas 1995

Abstract

Background: Estimates of the proportion of birth defects diagnosed before birth exist for only a few types of birth defects and for a few geographic regions in the United States. This population-based study examines rates of prenatal diagnosis for previously unstudied birth defects in a new geographic region. Methods: Active surveillance of 23 categories of birth defects among 111,902 infants born in 77 birthing hospitals in Texas in 1995 identified 852 infants or fetuses with major birth defects. Surveillance was conducted by the Texas Birth Defects Monitoring Program of the Texas Department of Health. Two regions were covered, the Houston/Galveston metropolitan area as well as the Lower Rio Grande Valley of Texas. Rates of prenatal diagnosis were evaluated for 23 different types of birth defects, using proportions and 95% confidence intervals. Results: One third of the 852 infants or fetuses with birth defects were prenatally diagnosed. Diagnosis rates varied greatly depending on the type of birth defects and were lower among infants born to Black and Hispanic women. More than 60% of anencephaly, encephalocele, gastroschisis and trisomies 13 and 18 were diagnosed antenatally. Many of the fetuses that were electively terminated had birth defects or combinations of birth defects that were potentially lethal. Prevalence rates for birth defects generally do not include fetuses that die or are electively terminated before 20 weeks of gestation. Thus, 36% of anencephaly, 21% of omphalocele, 15% of encephalocele and between 7 and 10% of spina bifida, hydrocephaly, renal agenesis, and trisomies 13, 18, and 21 were not included in our published rates. Conclusions: Published rates for specific types of birth defects are spuriously low. This should be considered when investigating alleged clusters and comparing rates of birth defects across geographic areas. Since many elective abortions are for lethal or potentially lethal birth defects, a major effect of prenatal diagnosis is the resultant decrease in infant mortality attributable to birth defects.

The population‐based prevalence of achondroplasia and thanatophoric dysplasia in selected regions of the US

“…In Texas virtually all cases of thanatophoric dysplasia were elective abortions, fetal deaths or early neonatal deaths as expected for a lethal condition. The observation that, in Texas, 9 of 43 cases or 20.9% of cases were elective abortions is consistent with the high frequency of elective abortions that has been observed for other lethal birth defects in Texas [Waller et al, 2000].…”

Pregnancy termination following prenatal diagnosis of anencephaly or spina bifida: A systematic review of the literature

“…We identified 15 articles meeting inclusion criteria using the search strategy (Harmon et al, 1995;Forrester and Merz, 2000;Waller et al, 2000;Olde Scholtenhuis et al, 2003;Biggio et al, 2004;Garne et al, 2005;Ghi et al, 2006;Nikkila et al, 2006;Tairou et al, 2006;Poretti et al, 2008;Aguilera et al, 2009;Amari et al, 2010;Lu et al, 2011;Machado et al, 2012). One additional article was found using Google Scholar (this article had cited one of the articles identified using the search strategy) (Adama van and one article was known to the authors and included (Shulman et al, 1994).…”

Mortality among infants with birth defects: Joint effects of size at birth, gestational age, and maternal race/ethnicity

“…LGA, large for gestational age; SGA, small for gestational age; preterm, <37 weeks gestational age at birth; term, 371 weeks gestational age at birth. are less likely to have their defect detected prenatally (Waller et al, 2000); NH-black and Hispanic women are less likely to terminate their pregnancies if a defect is detected (Bishop et al, 1997). It is also possible that the observed racial/ethnic differences are due to differences in the underlying or contributing causes of death that are unrelated to having a birth defect (e.g., unintended injury).…”