Is Pope Francis' contraception hint just a puff of smoke?

Pope Francis made headlines this week when he hinted that contraception may be acceptable in cases of Zika virus risk. But the BBC's Rome correspondent David Willey, who has written several books about the Vatican, does not believe it is a significant change of stance.

Time was when popes of the Catholic Church spoke confidently and, some believed, "infallibly" to their flock only from Rome, the centre of their worldwide religious domain.

Then came papal jet travel, and the possibility of holding informal news conferences with journalists in an Airbus at 36,000 feet, as the Pope flies away and back to Rome on his pilgrimages all over the world.

The transcontinental journeys of Popes Paul VI, John Paul II, Benedict XVI and Francis cancelled for ever the historical image of the pope as "prisoner of the Vatican".

It has been my privilege to accompany the last three popes on many of their journeys.

Most memorable were those with Pope, now Saint, John Paul, on dozens of his more than 100 foreign trips which took us over the Atlantic, Pacific and Indian oceans to countries as far away as Australia, Brazil, Japan, Kenya and the Seychelles..

First there came informal chats in seven different languages as the pope wandered back through the aisles in the economy class cabin, which sometimes led to chaotic scenes of cameramen scrambling over seats, and us straining our ears to overhear what he was saying and note it down or record it.

Then the news sessions gradually became more organised, with the pope's voice linked into the plane's intercom system.

Today, Pope Francis simply stands with a microphone in his hand by a bulkhead in his chartered Airbus to field questions from selected journalists.

He makes instant news when his Q&A sessions, neatly taped and edited for TV and transcribed for the written press, are released amid a flood of tweets soon after he lands.

What everyone was bursting to know in the light of the outbreak of the Zika virus in Central and South America: Will there be any change in the Catholic Church's teaching, particularly its 1968 ban on artificial contraception? It will soon be half a century since Pope Paul VI issued his controversial encyclical Humanae Vitae which in effect put a clamp on all future discussions on the subject.

Given government health service advice to women in some South American countries to postpone pregnancies because of the risk of birth defects among their future babies, should the Catholic Church relax its ban on abortion and artificial contraception?

Abortion, never, said Francis. It is a crime. But contraception, under certain emergency conditions, well, perhaps. Such as in the civil wars in the then Belgian colony of Congo during the 1960s when nuns who risked rape as war victims were authorised by Pope Paul VI to take the pill.

Was this a real chink in the curtain which came down in 1968?

The weakness of the Catholic Church's position on artificial contraception is that most Catholic women in most parts of the world have openly and steadily disobeyed papal teaching. Over 95% of sexually active Catholic women in the United States ignore the ban, according to independent opinion polls.

Flying over the United States on his return from his latest foreign trip to Mexico, Pope Francis put forward the ethical "lesser evil" argument, hinting that perhaps the use of contraceptives might be allowed to prevent the potential infection of a new-born with Zika.