First, this info was copied from a website that a local rabbi sent me to for answers on some q I had re Hasidic traditions. I trust it.
Q-11: I have heard that Hasidic women shave their heads on their wedding night. Is this true? If so, why?
Although some (not all) Hasidic woman do shave their heads, this practice is not based on a religious commandment, but is a custom based on a number of possible reasons. There is no requirement to shave one's head. But, as explained in Question #4 above, a woman does start to cover her hair after marriage, and some women prefer to keep their hair very short, because it is more comfortable under a wig or a scarf.
Regarding the custom (in some groups) to shave the hair on the wedding night, this can be traced to two things that got combined. First of all, a woman goes to the mikveh (ritual immersion) just before her wedding, and every part of her -- every single hair -- must be submerged simutaneously. Naturally, it is easier to do this if the hair is short and cannot float on the water.
In addition, there was a time in Europe when the non-Jewish kings or other rulers had the right to sleep with any bride in their kingdom on her wedding night. This was recently dramatized in the Mel Gibson movie, Braveheart, which was set in Old Scotland. But it was also true throughout much of Europe, including the Eastern and Baltic areas where most Hasidim lived. In many cases, "Prince Charming" was the local rapistand not so charming at all.
You can imagine how horrible it would be for the bride to have to submit to a rape. So the bride often tried to prevent this by shaving her head completely, in the hope that the ruler would think she was ugly and leave her alone. After the wedding, some women grew their hair back, while others chose to keep it short under their head coverings.
We should also note here that the American custom for everyone to ":kiss the bride" is not appropriate at Jewish weddings, and is not practiced by Hasidim or other Orthodox Jews. The personal privacy of the bride is to be respected, and a woman should not have to submit to kissing every man at the wedding. The bride and groom also do not kiss each other in public.
One very nice custom at all traditional Jewish weddings is that immediately after the ceremony (and before the reception), the bride and groom are led to a private room where they are left completely alone for a while. Two Jews serve as honor guards and stand outside the door, to be sure that their privacy is protected. During this time the bride and groom, who have been fasting all day in preparation for the wedding, break their fast with their first meal together as husband and wife. Many non-Jews today are also adopting this beautiful custom, because it gives the couple a chance to be alone with each other before facing the reception line and festivities that follow.