Birth Defect Multiple Birth Carrying multiple offspring at the same time increases the risk of some birth defects. FIGURE 42.16 shows the results of Yiwei Tang’s study of birth defects reported in Florida from 1996 to 2000. Tang compared the incidence of various defects among single and multiple births. She calculated the relative risk for each type of defect based on type of birth, and corrected for other difference that might increase risk such as maternal age, income, race, and medical care during pregnancy. A relative risk at less than 1 means that multiple births pose less risk of that defect occurring. A relative risk greater than 1 means multiple births are more likely to have a defect.

FIGURE 42.16 Prevalence, per 10,000 live births, of various types of birth defects among and single birth. Relative risk for each defect is given after researchers adjusted for the mother’s age, race, previous adverse pregnancy, as well as the infant’s sex and number of siblings.

What was the most common type of birth defect in the single-birth group?

To determine: The most common type of birth defect in the single-birth group.

Introduction: During the gestation period, the mother can have single birth or multiple births. Single birth is where the mother carries only one fetus during the gestation period in the womb. Multiple births are where more than one fetus is carried during the gestation period, such as twins, triplets, quadruplets, and more. Carrying more than one fetus in the womb results in insufficient supply of nutrient to the developing fetus. These fetuses become still-born or born with abnormalities.

Scientist YT studied the correlation between birth defects and multiple births in City F from 1996 to 2000. The scientist calculated the relative risk of birth defect with factors including type of birth, maternal age, economy, race, and medical care provided during pregnancy. The relative risks were calculated using a scale of 1. Relative risk lesser than 1 indicate that multiple births possess less risk of the occurrence of respective birth defects. Relative risk greater than 1 indicates that multiple births do possess a greater risk of the same. The generated data are given in Fig. 42.16.

According to the study, heart defects were the most common type of birth defect in the single-birth group, which may be due to genetic disorders.

The most common type of birth defect in the single-birth group is heart defects.