In vitro fertilisation (IVF) is a fertility treatment, which may involve several treatment cycles - Scottish Highers Human Biology - Question 6 - 2023

35 years

The number of women undergoing 1 treatment cycle is 24,000. For 11 treatment cycles, the number is 220. The percentage decrease is calculated as follows:

ext{Percentage Decrease} = rac{ ext{Initial number} - ext{Final number}}{ ext{Initial number}} imes 100 = rac{24000 - 220}{24000} imes 100 \\ = rac{23780}{24000} imes 100 \\ ext{Approximately} 99.1\%

The number of embryos transferred in the first treatment cycle is 34. To find the number of babies born, we apply the formula:

ext{Babies Born} = ext{Number of Transfers} imes rac{ ext{Birth Rate}}{100} = 34 imes rac{24}{100} = 8.16 \approx 8

The birth rate per embryo transfer is expressed as a percentage to standardize the success of IVF across different cycles. This allows easy comparison between cycles regardless of the number of transfers or participants involved.

27%

Generally, the birth rate per embryo transfer decreases as age increases when women use their own eggs. In contrast, using donor eggs tends to provide a higher birth rate, as younger donors usually have more viable eggs.

Donor eggs may be from younger women, which generally leads to higher success rates in embryo quality and fertility outcomes. Additionally, donor eggs might have fewer genetic mutations or abnormalities.