Assessed Reproductive Risk by Reviewing

Outline Chapter 4
Birth Defects and Prenatal Diagnosis
Genetic Assessment

Assessed Reproductive risk by reviewing:

◦Medical and pregnancy history

◦Extended family history

◦Presence of birth defects, genetic disorders, unexplained infant deaths, and recurrent pregnancy losses

Specific genetic testing clinically available for over 2,000 of the over 20,000 known genetic disorders

Screening Evaluations During Pregnancy

First trimester

◦Ultrasound (used to establish fetal viability, determine number of fetuses, confirm placental position, improve gestational dating, measure nuchal translucency); three-dimensional ultrasound sometimes used

◦First-trimester maternal serum screening (combined with ultrasound to identify 87% of fetuses with Down syndrome; also used to predict adverse pregnancy outcomes)

◦CVS (used for chromosome analysis, enzyme assay, or DNA analysis); CVS considered safest invasive prenatal diagnostic first-trimester procedure)

Second trimester

◦Second-trimester maternal serum screening (used to detect an increased risk for common birth defects, Down syndrome, and neural tube defects)

◦Second-trimester ultrasonography (used to diagnose neural tube defects, abdominal wall defects, facial clefts, renal and skeletal anomalies, heart defects, and other malformations)

◦Amniocentesis (tests the amniotic fluid directly for abnormal levels of biochemical compounds)

◦Magnetic resonance imaging (MRI): high-resolution ultrasound; can add to clinical understanding of an ultrasound variation

◦Fetal echocardiography: used as an assessment tool in fetuses with congenital heart disease

Diagnostic testing of fetal cells

◦Fluorescence in situ hybridization (FISH): used to identify specific chromosomes or to indicate small deletions of a defined region of a specific chromosome

◦Array comparative genomic hybridization (CGH): evaluates small, submicroscopic genomic deletions and duplications responsible for approximately 15% of known genetic disorders
Prevention

◦Consistent early prenatal care

◦Avoid alcohol and tobacco

◦Avoid exposure to infection and excess vitamin A

◦Avoid eating fish known with elevated mercury content

◦Take folic acid at least 3 months prior to conception

◦Maternal medical conditions can predispose an infant to birth defects or developmental disabilities

◦Maternal Diabetes and lupus increase the risk to the fetus if these disorders are not controlled

◦Assisted reproduction technology (ART)/ artificial insemination increases risk of disorder

◦It is important to think about screening and testing choices prior to pregnancy to research the tests in advance

◦Family’s psychosocial needs are a key factor

◦Nondirective counseling can help families understand their options and choose a course of action