This was in tuesday's NYT... thought it was interesting reading!

http://www.nytimes.com/2007/10/30/health/research/30chil.html?_r=1&oref=slogin

Childbirth: Purposely Breaking Water Does Not Speed Delivery

A large review of studies suggests that a common procedure in labor,
intentionally breaking the water, has no effect in reducing the labor
time or assuring the baby's health.

Amniotomy for Shortening Spontaneous Labor (The Cochrane Reviews) -
http://www.cochrane.org/reviews/en/ab006167.html

The procedure, sometimes called amniotomy, involves rupturing the
amniotic membranes to speed contractions. The procedure has been in
use for at least 250 years, although its popularity has varied.

The researchers reviewed 14 randomized controlled trials involving
almost 5,000 women and found little evidence for any benefits.
Amniotomy did not shorten the length of labor, decrease the need for
the labor-stimulating drug oxytocin, decrease pain, reduce the number
of instrument-aided births or lead to serious maternal injury or death.

The report, published Oct. 17 in The Cochrane Reviews, did find that
the procedure might be associated with an increase in Caesarean
sections and a reduced risk of a lower reading on the Apgar scale,
which rates the baby's condition at birth. But neither finding was
statistically significant.

"We advise women whose labors are progressing normally to request
their waters be left intact," said the lead author, Dr. Rebecca Smyth,
a research associate at the University of Liverpool. "There is no
evidence that leaving the waters intact causes any problems, and there
is not sufficient evidence to suggest any benefit to either themselves
or their baby."