By Lisa Maria Garza

DALLAS, July 18 (Reuters) - Most of the Texas clinics that abortion rights advocates predict will close because of a new law requiring tighter health and safety standards likely will remain open - at least if history is any guide.

Governor Rick Perry signed the new legislation on Thursday, capping a whirlwind month in which Texas became the center of a national campaign by anti-abortion activists to restrict when, by whom and where the procedure can be performed.

Included in the new Texas law are requirements that abortion clinics meet hospital-style health standards, ranging from installation of hands-free sinks to upgrades to ventilation systems. Supporters call the rules crucial safety standards.

The American Congress of Obstetricians and Gynecologists opposed them, saying that they are "unnecessary and unsupported by scientific evidence."

The new laws in Texas and elsewhere have alarmed abortion rights advocates, who see them as an attempt to thwart the right to abortion granted by the Supreme Court in 1973.

In Texas, Planned Parenthood announced on Thursday that it was closing one of its 13 abortion clinics that provide abortions, citing the new law. The nation's largest abortion provider said the rules could force all but a handful of the 42 abortion facilities in Texas to close down.

But similar warnings in other states have not come to pass.

Twenty-six states have laws that require abortion clinics to meet varying levels of hospital standards, according to the Guttmacher Institute, which supports abortion rights. Pennsylvania, Virginia and Missouri passed strict health and safety rules similar to Texas, it said.

In those three states, however, most clinics were able to stay open after the laws passed, some by reallocating dollars to comply with building upgrades, according to abortion providers and state health department officials interviewed by Reuters.

"It seems like an exaggeration from the other side that access is going to be cut off," said Mallory Quigley, spokeswoman for the anti-abortion Susan B. Anthony list.

Elizabeth Nash, state issues manager for the Guttmacher Institute, which favors abortion rights but does research cited by both sides, said the new law will have an impact in Texas but maybe less than the worst fears.

"Clinics will close," she said. "But I can't say we are going to go down to six."

Of the 24 clinics in Pennsylvania prior to a tough new law in 2011, one closed voluntarily, according to the state health department. The state closed two others for serious violations including a freezer lined with frozen blood, and stained surgical instruments in dirty drawers, according to reports by state inspectors.

Two others were consolidated into a third clinic but maintained the same level of service to women as before, said Dr. W. Allen Hogge, chair of the Obstetrics, Gynecology and Reproductive Sciences Department at the University of Pittsburgh Medical Center.

All of the remaining 19 clinics are in compliance, said Pennsylvania health department spokeswoman Aimee Tysarczyk.

"To be honest, we weren't counting numbers as far as how many were going to close," said Micaiah Bilger, spokeswoman for the Pennsylvania Pro-Life Federation, an anti-abortion group. "The purpose of the bill was to ensure basic health and safety standards for women that are going into these centers."

COMPLY OR CLOSE?

To remain open, some Pennsylvania clinics invested thousands of dollars to upgrade their facilities. Planned Parenthood of Southeastern Pennsylvania, for instance, said it spent about $400,000 to renovate two clinics after the state began implementing tougher standards in June 2012.

They installed hands-free sinks, new flooring and upgrades to heating, ventilation and air conditioning, said spokeswoman Maggie Groff.

"They had to spend large sums of money to comply that otherwise would have been put into patient care," Susan Frietsche, senior staff attorney at the Women's Law Project.

Only one clinic has closed in Virginia since a new law was implemented there earlier this year, the state health department said. No clinics have closed in Missouri because of a tough law passed there in 2007, abortion provider Planned Parenthood of Kansas and mid-Missouri said.

The national campaign to push for tighter restrictions on clinics gained momentum after the May conviction of a Philadelphia doctor, Kermit Gosnell, of murdering three babies born alive during abortions by severing their spinal cords.

Prosecutors in the case described his clinic as a "house of horrors" where recovery chairs were bloodstained and equipment broken.

The Gosnell case, Quigley said, shows "the abortion industry is not capable of policing itself."

Abortion rights activists said Gosnell was an exception among mostly safe and legal abortion providers.

In addition to the tough standards for clinics, the Texas law bans most abortions after 20 weeks of pregnancy, requires doctors performing abortions to have hospital admitting privileges, and limits the use of the RU-486 drug to end pregnancies.

It requires all abortion facilities to meet the standards of "ambulatory surgical centers" that perform outpatient surgery. First trimester abortions, which account for most such procedures, rarely require surgery.

"What is frustrating to us, as physicians, are rules coming out in Texas and other states that are catching on like crazy but are not medically based. They are to shut down abortion facilities," said Dr. Anne Davis, consulting medical director with Physicians for Reproductive Health, a national organization of doctors supporting the right to abortion.

Planned Parenthood said on Thursday it was preparing to sue the state of Texas over the new law, a tactic they employed in Missouri when the state in 2007 passed legislation requiring clinics to meet outpatient surgery standards for most abortions.

The two sides reached a settlement in 2010 under which Missouri waived some rules for clinics that only performed first trimester abortions, thus avoiding closings, said Peter Brownlie, chief executive of Planned Parenthood of Kansas and Mid-Missouri. (Additional reporting by Kevin Murphy in Kansas City and Gary Robertson in Richmond, Virginia; Editing by Greg McCune, Paul Thomasch and Ken Wills)

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