A Conservative MP is to launch an inquiry into unwanted pregnancy in an attempt to prevent the issue being hijacked by anti-abortion advocates in her own party.

The cross-party inquiry launched by Tory MP Amber Rudd comes after a year in which the government has invited anti-abortion group Life onto its sexual health advisory group, cut funding for pregnancy advice groups and launched a costly investigation into abortion clinics which found just 14 guilty of making essentially administrative errors.

"I am unequivocally pro-choice," said the Tory MP for Hastings. "Women who want abortions know what they're doing. They're grownups. The correct debate we should be having is how to improve contraception. It's about prevention."

The inquiry, which is supported by Labour's Sandra Osborne MP and Liberal Democrat MP Lorely Burt, will take evidence from several sexual health experts on three main areas: the increase in unwanted pregnancy among 30-somethings, the continued high rate of teenage pregnancies in the UK, the highest in western Europe, and increasing women's access to contraception. The latter includes looking at increasing access to long-acting reversible contraception, supported by pro-choice campaigners for reducing teenage pregnancy in particular.

Crucially, the inquiry will take evidence from "two key players" – Marie Stopes and the British Pregnancy Advisory Service (BPAS), which provide abortions as part of a nationwide pregnancy counselling service.

BPAS was dropped from the government's Independent Advisory Group on Sexual Health and HIV last year in favour of Life, an anti-abortion outfit which argues for an abstinence-based sex education.

The removal of BPAS in spite of a 40-year track record in providing advice came months before a bid by Nadine Dorries, a Conservative backbencher, and Frank Field, the former Labour minister, to strip abortion providers of their role in counselling women.

Campaigners who cheered the defeat of this bill then watched in horror as health secretary Andrew Lansley announced an immediate review of abortion clinics throughout the country, at an estimated cost of £1m.

"People think Nadine Dorries is the voice of the government because her voice is heard," said Rudd. "If the outcome of this is to change people's perception and make it clear that we are pro-woman and pro-choice then that is a fantastic byproduct."

The inquiry was welcomed by women's rights campaigners. Darinka Aleksic, campaign co-ordinator at campaign group Abortion Rights, described it as evidence of "a sane majority within all parties that supports a woman's right to choose and the medical benefits of providing good contraceptive services".

Women's rights campaigners have been shocked that abortion – which had been effectively depoliticised in this country – has become a political hot potato in the past year. Aleksic was among many to accuse the cabinet of offering hard-hitting statements on abortion in order to appease the socially conservative wing of the party outraged by its moves to allow gay marriage.

"Offering a quid pro quo is not the best way to pursue health policy", she said.

Abigail Fitzgibbon, public policy manager at BPAS, also supported the Rudd inquiry and she hoped it had support from a government that had shown itself able to "pander to a small political base" on the issue.

Rudd described health minister Anne Milton as "enthusiastic" about the review, which aims to make recommendations to the government by November.

Thursday's announcement on abortion clinics found 14 clinics in breach of administrative protocols out of more than 300. Lisa Hallgarten at Voice for Choice deplored "the effect this highly politicised investigation has had on those providing abortion. It has created a climate of fear among doctors and made some reorganise their services in ways that are actually creating delays for women and additional costs to the NHS".

Although Dorries is far from being close to the government, senior government ministers have been slow to criticise the increasing attacks on abortion clinics or the cuts in funding to advisors.