Still, transferring an embryo to a rhino is tricky because of the shape of the cervix.

尽管如此，由于子宫颈的形状，将胚胎移植到犀牛体内还是很棘手的。

Common convention is to transfer the embryo three days after fertilization, when the embryo has eight cells, or on day five, when the embryo is called a blastocyst, and has hundreds of cells.

通常的做法是在受精三天后移植胚胎，此时胚胎有八个细胞，或者在第五天移植胚胎， 此时胚胎被称为囊胚，有数百个细胞。

To increase the odds of success, which are as high as 40% for a woman younger than 35, doctors sometimes transfer multiple embryos at once, which is why IVF results in twins and triplets more often than natural pregnancies.

35 岁以下的女性成功几率高达 40%，为了增加成功几率，医生有时会一次移植多个胚胎，这就是为什么 IVF 比自然怀孕更容易生出双胞胎和三胞胎。