TENS is primarily used for maternity care to treat labour pains in women who are giving birth and make the process more bearable. 

This kind of technology can be used in the third trimester all the way to labour, helping to ease the pain of contractions and Braxton Hicks (false labour). 

Maternity TENS works just like general TENS does; it prevents pain signals from getting to the brain and allows the body to release endorphins.

TENS machines are one of the safest and most effective ways to alleviate the pain felt during childbirth, and they also promote mobility and sitting upright for the mum-to-be which can encourage descent and dilation.

TENS therapy can also be used alongside other kinds of pain relief, for a multi-method approach.  It is most effective when it is used right at
the beginning or labour, which will allow the body to build up adequate
endorphin levels to help ease the pain.