There is some evidence to support not getting into the tub until you're at least five centimetres dilated, longer if you can. In some situations, water can slow labour down, but if you're in a well established contraction pattern it isn't likely to have that effect.
Additionally you want to get into the water mainly because it will offer the most benefit. Getting in too early on might not provide you with the same relief as entering much later when the spasms are stronger. It is, however , important to remember that each birth is unique. If you are living in Los Angeles you can find best water birth los angeles.
If strong spasms are inhibiting a woman's ability to work with the contractions and relax in order to permit labour to progress, entering water to relax might actually aid in labour advancing. Some maternity care providers recommend trialing water – entering for about an hour and watching to see if contractions slow, stay steady or actually progress quickly.
If contractions seem to be to space out too much and become less strong your midwife or physician might recommend leaving the tub until you're in more of a strong active labor pattern. Whenever you can, it's best to be fully submerged to at least your chest.
Although any bit of warm water can help in coping with contractions, being fully submerged provides more buoyancy and warmth to provide the most pain relief. Being well immersed might also help a mother to feel more secure, as if she's in a safe nest preparing for her baby's arrival.