The Rebbe addresses a question about sperm testing to aid in childbirth. Based on a directive from the Rebbe Rayatz, he permits it when medically needed, favoring the method of collection from the womb post-intercourse. While some halachic authorities, especially Hungarian ones, are stringent, the Rebbe follows the ruling of the Tzemach Tzedek.
https://www.torahrecordings.com/rebbe/igroskodesh/015/008/5408