Lamaze or psychoprophylaxis is the most popular birth preparation method in the western world. Over 1 million women every year attend Lamaze classes. Lamaze teaches relaxation but also a pattern of rhythmic breathing to cope with contractions. This was the method which made the NCT so popular in the latter part of the 20th century and which your mum might have learned if she attended classes. To be effective, it needs to be taught well and a lot of time spent on practice. With the expanding content of classes, the Lamaze preparation tended to get diluted in NCT classes and hence less effective. Rumoured that the Duchess of Sussex used this as her preparation for the birth of Archie. I teach Lamaze if this is something you may be interested in.