A hospital reviews the outcomes of IVF treatment for different age groups. Table 1 shows the number of embryo transfers and the number that resulted in a li...
Question 1 Report
A hospital reviews the outcomes of IVF treatment for different age groups. Table 1 shows the number of embryo transfers and the number that resulted in a live birth. In every case, one embryo was transferred to the uterus. The figures do not show whether the sperm came from a partner or donor. Doctors use this information when discussing treatment options, but explain that an individual’s chance can also be affected by egg quality, sperm quality and health. The table is not evidence that age alone causes infertility.
| age of female patient / years | number of embryo transfers | number resulting in a live birth |
|---|---|---|
| under 30 | 120 | 48 |
| 30 to 34 | 150 | 51 |
| 35 to 39 | 140 | 28 |
| 40 and over | 90 | 9 |
(a) Calculate the percentage of embryo transfers for patients under 30 that resulted in a live birth. Show your working. [2]
(b) Suggest two reasons why doctors should be careful when using Table 1 to predict the outcome for one patient. [2]
Answer Details
(a) The percentage of transfers resulting in a live birth is:
\[\frac{48}{120}\times100=40\%\]
Therefore, 40% of embryo transfers for patients under 30 resulted in a live birth. [2]
(b) Doctors should be cautious because the table gives results for groups, not a prediction for one individual patient. Also, success can be affected by other factors, including egg quality, sperm quality and general health. [2]
Other acceptable cautions are that the age groups have different sample sizes and that some differences in group results may occur by chance. The table identifies an association in these data, but does not show that age alone causes infertility.
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