While Europe increasingly questions the practice of circumcising boys, US paediatricians are about to say that the medical case for it is getting stronger. Most US adult men are circumcised, but the number of newborns having the op is falling, and is now below 50% in some states - intensifying the dilemma for parents.

Stephen Box - like most American men - is circumcised.

Seven months ago, as a new father, he had to decide whether to circumcise his newborn son. It was not a straightforward decision.

"I was uncomfortable he would be different from me," he begins.

Stephen Box is part of a generation in the US for whom circumcision was almost universal - so much so that an uncircumcised boy would stand out in the locker room, his most private part an object of curiosity, perhaps even ridicule.

To bring a knife to your eight-day-old baby is not an easy thing to do Kimberly Birbrower, Jewish mother

"Little boys can be ruthless on little boys who are different," he says.

But Stephen and his wife decided not to circumcise their son. They felt they could only justify the operation if they could find a good reason for doing it - and they didn't.

"Just because that's the way we were raised, doesn't make it correct," Stephen says.

"There was no strong argument for doing it, and there was room for hesitation.

"It's tools-in-hands on the special part of a little boy."

Image caption To cut or not to cut: Stephen Box decided against

At the end of June, Germany was shaken by a court ruling that circumcision of minors was harmful, and a violation of a child's rights.

Jews and Muslims were outraged, seeing the ruling as an attack on one of the fundamental parts of their faith.

The German controversy Cologne court rules in June that circumcision of male minors for religious reasons causes "bodily harm" and violates "bodily integrity"

Court says neither religious freedom nor rights of parents are justification for it

Outrage among Jews and Muslims and the government steps in offering assurances that circumcisions will be allowed to continue

Many doctors now refuse, fearful of prosecution Germany divided over circumcision ban

Editorials and opinion pieces in major US newspapers expressed similar outrage and 20 representatives in Congress wrote a letter to the German ambassador in Washington, expressing "deep concern".

Unlike in Europe - where rates are low, and circumcision is mostly confined to the Jewish and Muslim communities - circumcision is one of the most common operations in the US.

Three-quarters of American adult men are circumcised. There are over one million procedures each year, or around one every 30 seconds.

But rates are falling, as parents - like Stephen Box and his wife - are opting to break with tradition, and alongside this, an increasingly vocal anti-circumcision movement has emerged.

Figures from the Centers for Disease Control and Prevention (CDC) show that 55-57% of newborn boys in the US are now circumcised in hospital, and the numbers are dropping by around 1% each year.

Having your baby boy circumcised was, for many years, the "default position", says Dr Douglas Diekema, professor of paediatrics at the University of Washington.

Circumcision was thought to be as normal as a vaccination. Until the end of the 1970s doctors would say "When would you like your baby circumcised?", now they are more likely to say "Would you like your baby circumcised?" says Diekema.

A key turning point came in 1999 when guidelines said the medical case for circumcision (a reduced risk of urinary tract infections and penile cancer) was not strong enough to either recommend routine circumcision of newborn boys, or discourage it.

Parents, the guidelines said, should be the ones to decide.

What is male circumcision? Removal of foreskin from penis - the fold of skin that covers the tip

About 30% of men globally are circumcised

One of oldest surgical operations, dating back more than 4,000 years

"You are doing a procedure on someone who cannot make a decision for himself - it's a difficult choice for both parents and physicians," says Dr Marvin Wang, co-director of the Newborn Nurseries at Massachusetts General Hospital, who has conducted hundreds of circumcisions.

It is, he says, more a "cultural decision" than a medical one, and therefore, for parents to decide, while he advises on the pros and cons.

Wang says most parents come in with fervent beliefs - and what a doctor says makes little difference.

"The bottom line is... they stick to their guns. They choose the pieces of information that bolster their argument and run with that."

If they opt for circumcision, he invites them to watch and does all he can to reduce pain for the baby, with an injection of local anaesthetic to the area.

One of the most common reasons given for the surgery is that a father wants his son to look the same as him, or is afraid his child will be teased if left uncircumcised, Wang says.

He estimates that in his hospital around six out of 10 newborn boys have the surgery - just higher than the national average, and a rate which has stayed stable in the 15 years he has worked there.

Media playback is unsupported on your device Media caption How is a circumcision actually done? A demonstration on a doll

Circumcision rates vary wildly across the country - from more than 80% of newborns in states including Nebraska, Iowa, Wisconsin and Kentucky, to around 20% on the West Coast, according to some calculations.

"It might be part of a new trend," says Lorran Garrison who lives in Los Angeles, and decided against circumcising her son, now 14 months old.

"In my birthing class, of the five boys, only one got circumcised. It was kind of odd, because when we grew up, everyone was circumcised."

At my baby shower, a bunch of them came over and said 'We can't believe that you are not doing this' Jessica Loveless, LA mother

Explaining her decision not to circumcise her son, she says simply: "It doesn't seem medically necessary. If it's not broken, don't fix it."

But she says there was "an assumption" she would, and her mother was unhappy with her decision.

"She really wanted her grandson circumcised… She thinks my son could be traumatised by teasing and that it could get infected."

Jessica Loveless, another mother in LA, also found herself having to justify her decision not to circumcise her son - in her case, to her husband's family.

"At my baby shower, a bunch of them came over and said 'We can't believe that you are not doing this.'"

She worries that her friends may also question her decision, and has avoided raising the subject.

For Jessica, it was an emotional decision. "I do feel somewhat passionately about it," she says. "It just looks so painful."

Male circumcision is almost universal in many places with predominately Jewish or Muslim populations - like Saudi Arabia, Jordan, Afghanistan, Israel and the Palestinian territories.

In some African countries it is seen as a a rite of passage for a boy into adulthood.

Circumcision and religion Image caption The circumcision of Jesus is a common subject in Christian art Male circumcision is compulsory for Jews and is conducted on the eighth day of a child's life - regarded a sign of covenant with God

It is commonly practised among Muslims, but at no fixed age

Jesus was circumcised (see above) and there was debate among early Christians as to whether it should be part of Christian faith - but the church decided against it More from BBC Ethics

In the US, the popularity of circumcision dates back 140 years to Dr Lewis Sayre, one of the founders of the American Medical Association, says David Gollaher author of Circumcision: A History of the World's Most Controversial Surgery.

We think of scientists as very objective, but scientists are people Brian Earp, Medical ethicist

Sayre believed that many medical conditions had their root in a dysfunction in the genital area, and that circumcision could be used to treat a startling array of problems, from depression to mental health issues, syphilis and epilepsy.

Circumcision was also promoted as a way of discouraging masturbation, and was regarded as clean and hygienic. It was particularly popular among the higher classes, and was seen as a sign of being well-off enough to afford a birth at hospital rather than at home.

Sayre's theories were later debunked, but not before being widely picked up in other English-speaking countries, in particular in the UK, Canada, Australia and New Zealand, Gollaher says.

US troops also took male circumcision to South Korea after WWII, where it remains extremely popular.

In the UK, around one-third of men were circumcised just before the introduction of the National Health Service in 1948. But the newly-created NHS ruled that circumcision was not medically necessary, and therefore would not be covered. Rates plummeted after that, says Gollaher.

About 9% of men in the UK are now circumcised according to WHO figures (other estimates are slightly higher).

Meanwhile in the US, circumcision came to be so widespread, "it became part of how people viewed the normal body," says Gollaher.

It had become a cultural norm, he says, transferred from generation to generation, from father to son, and from doctor to trainee - but it is a norm that is increasingly being challenged.

One reason for this is the greater emphasis worldwide given to the rights of the child, manifested most obviously in the UN Convention on the Rights of the Child, which came into force in 1990.

European challenges A state in Austria and two hospitals in Switzerland temporarily suspended circumcisions in response to the German ruling, but have now resumed operations

and two hospitals in temporarily suspended circumcisions in response to the German ruling, but have now resumed operations Norway 's ombudsman for children's rights proposed Jews and Muslims replace circumcision with a symbolic ritual, while some MPs have called for minimum age of 18

's ombudsman for children's rights proposed Jews and Muslims replace circumcision with a symbolic ritual, while some MPs have called for minimum age of 18 In the Netherlands , the Royal Dutch Medical Association recommends a "policy of deterrence" on male circumcision

, the Royal Dutch Medical Association recommends a "policy of deterrence" on male circumcision In Sweden, all circumcisions must be done within the first two months of a child's life, under anaesthetic, and by a registered physician or nurse

The German court ruling in June was framed in terms of children's rights, as was a ruling in 2010 by the Royal Dutch Medical Association, which argued that circumcision of boys "conflicts with a child's right to autonomy and physical integrity".

It said there was a good case for banning the practice, but stopped short of this, recommending instead a "powerful policy of deterrence".

In Norway too, the children's rights ombudsman is now recommending Jews and Muslims conduct a symbolic ritual, instead of a circumcision, and some MPs want a minimum age of 18.

In the US (which has not ratified the UN Convention on Rights of the Child) the anti-circumcision movement - or genital autonomy movement as it sometimes called - has "mushroomed" in the last few years, says Steven Svoboda, founder and executive director of Attorneys for the Rights of the Child, based in California.

This group has so far persuaded 18 US states to stop providing male circumcision as part of Medicaid, the health programme which covers the poor.

"This is very significant," Svoboda says. "We are talking hundreds of thousands of boys who won't be circumcised as a result."

Last year campaigners calling themselves "intactivists", tried to get male circumcision banned in San Francisco, gathering over 12,000 signatures - more than enough to put the question on a public ballot - but the attempt was thwarted when a judge ruled that the city did not have the authority to regulate medical procedures.

Those who oppose male circumcision argue that it is not medically necessary (except in rare cases) and involves the irreversible removal of healthy flesh from a child, who is not able to give consent.

I've often wondered if I have the right to do that to my child Kamal Nawash, Free Muslims Coalition

Opponents also argue that circumcision may affect a man's sexual experience. The foreskin is not "a useless flap of skin", says Lauren Jenks founder and president of The Whole Network, one of a crop a US-based campaign groups lobbying against the practice.

"It is one of the most sexually sensitive parts of a male's body, with thousands of specialised nerve-endings," she says.

But against this background of scepticism in Europe, and among some in the US, the influential American Academy of Pediatrics is set to issue new guidelines on 27 August saying the medical case for circumcision has become stronger.

"Data on harm has not changed much, but the data on benefits has," says Dr Douglas Diekema, who helped draft the new advice.

This data is research that links male circumcision with a lower rate of HIV infection in heterosexual men. On the basis of the same work, the World Health Organization (WHO) is encouraging circumcisions as part of its overall HIV-reduction strategy in Africa (though it is not without its critics).

The new guidelines, says Diekema, will be tweaked to include this data on HIV, and will remain broadly similar to current advice, with the emphasis - as it is now - on parental choice.

But how can the US paediatricians come to such different conclusions from their Dutch counterparts?

Diekema acknowledges that circumcision policy is a minefield: "Quite frankly, with this sort of procedure, there will always be a huge values component."

"We think of scientists as very objective, but scientists are people," says Brian Earp, an American research associate with the Uehiro Centre for Practical Ethics at Oxford University.

"It ends up being something of a political choice," adds David Gollaher - who points out that US physicians themselves are divided.

An organisation called Doctors Opposing Circumcision has around 500 active members in the US, and thousands worldwide, but does not disclose their identities.

WHO on the risks When conducted on newborns in a clinical setting, complications are rare and usually minor

In adults, the operation is more complex. Under optimal conditions, complication rates are about 0.2-0.4%, principally bleeding, haematoma and sepsis

Circumcisions conducted in unhygienic conditions, by inexperienced providers with inadequate instruments, or with poor aftercare, can result in serious complications and even death WHO Male Circumcision report

The group's executive director, John V Geisheker, says many working doctors are afraid to come out against circumcision, fearful that they might lose referrals, the respect of their colleagues, or - and this is a major concern, he says - be accused of anti-Semitism.

For medical ethicists the question of circumcision has also shot up the agenda in recent years, says Raanan Gillon, former editor of the Journal of Medical Ethics.

Any decision on the rights and wrongs of child circumcision has to balance the rights of the child, with the rights of the parents and the right to religious freedom - and the US puts considerable emphasis on the second and third of these.

Gillon, who favours the model of giving parents the choice, emphasises that the impact of restricting circumcision on the Jewish and Muslim faiths would be huge.

"How much harm would arise if you start conflicting with people's religious cultures? If it became forbidden, this would have a pretty major effect on two major world religions," he says.

But some argue that religion has acted as a cloak, making male circumcision a no-go area for debate - just as for many years, Westerners were reluctant to condemn female circumcision in countries where it was a cultural tradition.

Genital mutilation? Activists often compare male circumcision with female genital mutilation (FGM) - sometimes using the term "male genital mutilation", or "MGM"

"The severity is different," says Soraya Mire, author of The Girl with Three Legs, about her own brutal circumcision in Somalia when she was 13 years old - but, she says, "that first cry, that first cut, it is like removing a child's rights"

But many find any comparison between male circumcision and FGM extremely offensive - especially those for whom circumcision is done for religious reasons

Far from causing harm, they regard circumcision as a sign of one's relationship with God

"There are many traditions that are thousands of years old that we've sort of woken up to and said, 'Maybe these are not justifiable any more?'" says the Oxford medical ethicist, Brian Earp.

"As we evolve morally as a species we need to ask, 'Do they still make sense today?'"

Religious traditions should not be exempt from such scrutiny, he argues.

Even within both the Jewish and Muslim communities, there are some who question male circumcision, for example the group Jews Against Circumcision.

It is a very complex issue, says Kamal Nawash, a Washington DC lawyer and president of the Free Muslims Coalition.

Nawash has successfully fought for female circumcision to be considered a form of persecution in US courts, and regards the German court ruling on male circumcision as sound in its reasoning. But he's not entirely clear where he stands.

"I was circumcised," he says. "Chances are, if I have a son, I will have him circumcised as a matter of tradition."

But he muses: "I've often wondered if I have the right to do that to my child - to cause him that much pain."

Image caption Many Jews, like Kimberly Birbrower, feel one of the basic tenets of their religion is under threat

Some parents who opt in favour of circumcision now feel they are swimming against the tide of public opinion - like Kimberly Birbrower, a Jewish mother who lives in LA, where rates are among the lowest in the country.

"Just as with any parenting trend... once the tide turns, it turns," she says, adding this has created a difficult atmosphere for people like herself.

"To bring a knife to your eight-day-old baby is not an easy thing to do."

"I found it very scary," she says, recalling the day two years ago when her son was circumcised.

But it was, she says, "very beautiful" and "very spiritual".

She says the issue has become "highly charged", giving the example of an internet chat room discussion. When she said she had circumcised her son, "the women just went ballistic on me", she says.

"It's the kind of vitriol you hear from homophobic people talking about gay marriage.

"I feel the conversation around it has become very anti-Semitic. I find it very painful, and very surprising."

Take the most private part of the male body, add parenting rights, children's rights, disputed science, history, tradition and a dollop of religion, and you have the recipe for a controversy that will run and run.