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Prenatal exposures and congenital heart defects in Down syndrome infants
1Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas 75235, USA.
Insights
This study found no significant prenatal risk factors differentiating infants with Down syndrome and congenital heart defects from those without. Cardiac malformations in Down syndrome may stem directly from chromosomal duplication.
Area of Science:
- Genetics
- Developmental Biology
- Pediatrics
Background:
- Congenital heart defects (CHDs) are common in infants with Down syndrome (DS).
- Identifying prenatal risk factors for CHDs in DS is crucial for understanding developmental pathways.
- Previous research has not definitively linked specific maternal or environmental exposures to CHDs in DS.
Purpose of the Study:
- To investigate potential differences in maternal and environmental prenatal risk factors between liveborn infants with Down syndrome and congenital heart defects (CHDs) versus those with Down syndrome but without CHDs.
- To evaluate risks associated with maternal illness, drug ingestion, substance use, and chemical exposures during early pregnancy.
Main Methods:
- A case-control study design was employed, comparing 89 infants with Down syndrome and CHDs (cases) to 82 infants with Down syndrome without CHDs (controls).
- Interviews were conducted using a standardized questionnaire focusing on the three months before and after the last menstrual period.
- Data collected included maternal health, substance use, and environmental exposures.
Main Results:
- No significant differences were observed in maternal age, socioeconomic status, or educational background between cases and controls.
- Maternal illness, medication use, alcohol, cigarette, or caffeinated beverage consumption did not differ between groups.
- While environmental exposures like pesticides and hair dyes were common, their prevalence did not significantly differ between mothers of cases and controls.
Conclusions:
- This study did not identify specific maternal or environmental prenatal risk factors that distinguish infants with Down syndrome and congenital heart defects.
- The findings suggest that cardiac malformations in Down syndrome may be an intrinsic consequence of the chromosomal abnormality (trisomy 21).
- Further research with larger sample sizes may be needed to detect subtle risk factor differences or explore other etiological factors.
Abstract:
The purpose of this study was to determine whether there are important differences in maternal and environmental prenatal risk factors between liveborn Down syndrome infants with congenital heart defects and Down syndrome infants without heart defects. Using a case control study design, we evaluated the risk associated with maternal illness, drug ingestion, substance usage, and chemical exposures in the home or workplace. The period of risk selected was 3 months before and 3 months after the last menstrual period, because cardiac development occurs early, before the mother may become aware of her pregnancy. Because fetal survival in Down syndrome may be more vulnerable to various exposures, controls were selected who also had trisomy 21. Of 171 infants studied, 89 were cases with congenital heart disease, and 82 were controls without heart disease. All interviews were performed by one nurse practitioner using a structured standardized questionnaire. Cases and controls had similar maternal ages, family incomes, parental education levels, and contraceptive practices before pregnancy. No differences were found between case and control mothers for maternal illness, medication use, or consumption of caffeinated beverages, cigarettes, or alcohol. Reporting of recreational drug usage was infrequent, may reflect underreporting, and did not differ between cases and controls. Maternal exposures were commonly reported for pesticides (50%), hair dyes (22%), craft paints (8%), varnishes (7%), and solvents (3.5%). However, in none of the categories was maternal exposure significantly more prevalent among case mothers than among control mothers. The failure of this study to identify risk factors for cardiac malformations may be attributable to the small differences in reported frequencies reducing statistical power or to the possibility that cardiac malformation in Down syndrome is a direct result of chromosomal duplication.
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