Is it permissible for me to delay performing ghusl (ritual bath) after major ritual impurity until the morning, due to my desire to conceive, knowing that I am an employee and cannot perform ghusl until the morning, and that this matter is based on scientific information?

Prayer has specific times and conditions, such as the entry of its time and ritual purity (tahara). If the questioner prayed without being ritually pure from janabah (definition) for the reason mentioned, then she has committed a grave error, as what was mentioned does not permit her to do so. And if she does not pray until the time for Fajr prayer expires, then this is even more severe. She must repent and make up the prayers she missed, for complying with Allah's command is among the greatest means of obtaining sustenance and righteous offspring.