Biology: The Dynamic Science (Mind...

4th Edition
Peter J. Russell + 2 others
ISBN: 9781305389892



Biology: The Dynamic Science (Mind...

4th Edition
Peter J. Russell + 2 others
ISBN: 9781305389892
Textbook Problem

People considering fertility treatments should be aware that such treatments raise the risk of multiple births and that multifetal pregnancies are associated with an increased risk of some birth defects. The Table 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 differences that might increase risk: maternal age, income, race, previous adverse pregnancy experience, education, Medicaid participation during pregnancy, and the infant’s sex and number of siblings. A relative risk of less than 1 means a defect occurs less often with multiple births than single births. A relative risk of greater than 1 means that multiples are more likely to have a defect.

Prevalence, per 10,000 Live Births, of Various Types of Birth Defects among Multiple and Single Births

Prevalence of Defect Relative Risk
Multiples Singles
Total birth defects 358.50 250.54 1.46
Central nervous system defects 40.75 18.89 2.23
Chromosomal defects 15.15 14.20 0.93
Gastrointestinal defects 28.13 23.44 1.37
Genital/urinary defects 72.85 58.16 1.31
Heart defects 189.71 113.89 1.65
Musculoskeletal defects 20.92 25.87 0.92
Fetal alcohol syndrome 4.33 3.63 1.03
Oral defects 19.84 15.48 1.29

Tang found that multiples have more than twice the risk of single newborns for one type of defect. Which type?

Source: Y. Tang et al. 2006. The risk of birth defects in multiple births: A population-based study. Maternal and Child Health Journal 10:75–81.

Summary Introduction

To review:

The defect that has more than twice the risk in the multiple-birth group in comparison to the single-birth group.


In Florida, from the year 1996 to 2000, a study was conducted on live births. This study was made on the risk factor of birth defects in children born per 10,000 live births. It was observed that the birth defects had a higher risk value in the multiple-birth group. The prevalence of these birth defects was comparatively lower in the single-birth group.


The structural or functional anomalies that are present in the newborn, which may have developed at or before birth, are birth defects. These conditions are responsible for affecting the physical, developmental, or mental health of the children. The birth defects are often seen in parents seeking fertility treatments. This is because of the hormone change that is caused by injecting the ovulation and egg maturation hormones. There are various other reasons that further result in causing these birth defects...

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