Читать книгу Genetic Disorders and the Fetus - Группа авторов - Страница 49

Concerns about normal fetal development after exposure to medications, alcohol, illicit drugs, chemical, infectious or physical agents, and/or maternal illness are among the most common reasons for genetic counseling during pregnancy. Many of these anxieties and frequently real risks could be avoided through preconception care. Public health authorities, vested with the care of the underprivileged in particular, need to focus their scarce resources on preconception and prenatal care and on the necessary public education regarding infectious diseases, immunization, nutrition, and genetic disorders.

In preconception planning, careful attention to broadly interpreted fetal “toxins” is necessary, and avoidance should be emphasized. Alcohol, smoking, illegal drug use, certain medications, and X‐ray exposure require discussion. Estimates of the prevalence of the fetal alcohol spectrum disorder approximate 2 per 1,000 livebirths⁶⁹² in the United States but in certain regions and countries rates reach as high as 10 percent.^693–695 There is a limited list of known and proven human drug teratogens⁶⁹⁶ (see Chapter 3). Maternal use of specific teratogenic medications,⁶⁹⁷ such as isotretinoin, may be missed, unless the physician expressly inquires about them.

Preconception advice to avoid heat exposure in early pregnancy is appropriate. Our observations showed a 2.9 relative risk for having a child with a NTD in mothers who used a hot tub during the first 6 weeks of pregnancy.⁶⁹⁸ High fever in the very early weeks of pregnancy is a potential teratogen⁶⁹⁸ and should be avoided and treated promptly. Animal studies show that commonly used drugs enter the fetal brain.⁶⁹⁹

A report from the Spanish Collaborative Study of Congenital Malformations noted a 2.8‐fold increased risk of Down syndrome in the offspring of women ≥35 years of age and who were taking oral contraceptives when they became pregnant.⁷⁰⁰