A parent asks the nurse why their newborn has a congenital deformity. Which is the best response by the nurse to explain the cause related to fetal development?

A. "Deformities are usually caused by events happening during labor and delivery, not during pregnancy.": Most congenital deformities originate during embryonic or fetal development, not during the birth process. Labor complications may cause trauma, but they do not typically result in structural malformations. B. "Genetics is the only reason babies are born with deformities, so environmental factors are not involved.": Both genetic and environmental factors contribute to congenital anomalies. Teratogens such as certain drugs, infections, or radiation can significantly impact fetal development, especially during critical organ formation periods. C. "Most major organ development occurs early in pregnancy, between weeks 3 and 8, so exposure to harmful substances during that time may have caused the deformity.": The embryonic period, from weeks 3 to 8, is when organogenesis occurs. During this stage, teratogenic exposure can cause structural malformations. D. "Deformities occur because organs develop throughout the entire pregnancy, so problems can happen anytime.": Although functional maturation continues throughout pregnancy, structural organ development mainly occurs in the first trimester. Therefore, the risk for major congenital malformations is greatest early in gestation.