[TheDude]

Contractions on the way up are your friend... They boost the dive reflex - so your body spends less oxygen. Think of them in a positive way - when you get them, you can be sure your body is in an oxygen saving mode, allowing you to dive longer and safer.

Problem is only if you feel contractions already on the way down and at the bottom, as it is thought to increase the risk of lung squeeze.

If you spend some time in water, after cca a week of diving you will start to feel more comfortable with diving, more relaxed, and this should postpone the onset of contractions. Also important is to be completely relaxed - especially the chest area and diaphragm.