Q. I heard that some great Chasidishe Rebbes would not permit women to go to the mikva on nittel night. Is that true?
A. Responsa Vedorashto Vechokarto (Y.D. 15 note) quotes Daas Hak’dosho (7: 17) in the name of the Gaon of Munkatch zt’l, that one should abstain from marital relations on Nittel Nacht, since it may affect the offspring conceived in that particular night. He mentions that the Satmar Rebbe zt’l would order the closing of mikvaos on Nittel. However, Minchas Elozor would permit on the night of tevila, after midnight or when Nittel falls on a Shabbos night. See question 960 regarding weddings on Nittel.
Horav Shlomo Miller’s Shlit’a opinion is that one should keep the traditions of his family and community.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller Shlit’a