hese disorders of globin-chain synthesis are the most common single-gene disorders worldwide (Forget, 2013; Vichinsky, 2013). As many as 200 million people carry a gene for one of these hemoglobinopathies, and hundreds of mutations are known to cause thalassemia syndromes (Chap. 56, p. 1084). In endemic areas such as Mediterranean and Southeast Asian countries, counseling and other prevention strategies have reduced the incidence of new cases by up to 80 percent (Cao, 2013).
The American College of Obstetricians and Gynecologists (2015a) recommends that individuals of high-risk ancestry be ofered carrier screening to allow them informed decision making regarding reproduction and prenatal diagnosis. One method of early prenatal diagnosis is preimplantation genetic diagnosis (PGD), which is coupled with assisted reproductive technologies. Described in Chapter 14 (p. 295), PGD is available for patients at risk for certain thalassemia syndromes (Kuliev, 2011).
• Individuals of Eastern European Jewish Descent
Most individuals of Jewish ancestry in North America are descended from Ashkenazi Jewish communities and are at increased risk for having ofspring with one of several autosomal recessive disorders. These include Tay-Sachs disease, Gaucher disease, cystic ibrosis, Canavan disease, familial dysautonomia, mucolipidosis IV, Niemann-Pick disease type A, Fanconi anemia group C, and Bloom syndrome. The American College ofObstetricians and Gynecologists (20 16c, 2017a) recommends preconceptional counseling and screening for these in this population. Carrier frequency and features of these conditions are discussed in Chapter 14 (p. 290).
During preconceptional screening, information is sought regarding infertility; abnormal pregnancy outcomes that may include miscarriage, ectopic pregnancy, and recurrent pregnancy loss; and obstetrical complications such as cesarean delivery, preeclampsia, placental abruption, and preterm delivery (Stubblefield, 2008). As discussed in Chapter 35 (p. 646), details involving a prior stillbirth are especially important. For example, Korteweg and associates (2008) identiied chromosomal abnormalities in 13 percent ofstillborns who underwent karyotyping. Reddy and colleagues (2012) confirmed that chromosomal microarray analysis (CMA) yielded better detection of genetic abnormalities than did standard karyotyping, primarily because nonviable tissue can be used for the analysis. CMA is described and illustrated in Chapter 13 (p. 271). Identiication of a genetic abnormality in a stillborn can help determine the recurrence risk and aid in the preconceptional or prenatal management in subsequent pregnancies.
Women at both ends of the reproductive-age spectrum have unique outcomes to be considered. First, according to the CDC, in 2010,i3.4 percent ofbirths in the United Stateswerein women between the ages of 15 and 19 years (Martin, 2012). These adolescents are at increased risk for anemia, preterm delivery, and preeclampsia compared with women aged 20 to 35 years (Usta, 2008). he incidence of sexually transmitted diseases-common in adolescents-is even higher during pregnancy (Niccolai, 2003). Unfortunately, because most of their pregnancies are unplanned, adolescents rarely seek preconceptional counseling.