the Fatwa Department Research Committee - chaired by Sheikh `Abd al-Wahhâb al-Turayrî
A ritual bath (ghusl) is required for major ritual impurity that is brought by various causes. Some of these reasons are exclusively for women. These are: menstruation, childbirth, and post-natal bleeding.
Others causes are shared by men and women. All of these are on account of sexually activity. Ritual impurity brought on by sexual activity is referred to in Islamic Law as janâbah.
Janâbah occurs for two reasons:
1. ejaculation or orgasm resulting from sexual stimulation
- or -
2. sexual penetration entailing the entry of the male sexual organ during coitus
In the case of restoring the zygote to the womb after in-vitro fertilization, neither of these is the case. Therefore, no ghusl will be required.
And Allah knows best.
Source: Islam Today