The made-up model continues. Each embryo has a chance of 1/4 of implanting, and the embryos do not…

Step 1. $3$ embryos, at least one. None: $\dfrac{27}{64}$. At least one: $1 - \dfrac{27}{64} = \dfrac{37}{64} = 57.8\%$.

Step 2. $3$ embryos, two or more. Exactly one: $3 \times \dfrac{1}{4} \times \dfrac{9}{16} = \dfrac{27}{64}$. Two or more: $1 - \dfrac{27}{64} - \dfrac{27}{64} = \dfrac{10}{64} = 15.6\%$.

Step 3. $4$ embryos, two or more. None: $\dfrac{81}{256}$. Exactly one: $4 \times \dfrac{1}{4} \times \dfrac{27}{64} = \dfrac{108}{256}$. Two or more: $1 - \dfrac{81}{256} - \dfrac{108}{256} = \dfrac{67}{256} = 26.2\%$.

Step 4. The rise. $26.2 - 15.6 = 10.6$ percentage points.