Your article on my alleged thoughts about the pill began with the sentence: "Roman Catholic leaders have pounced on a 'confession' by one of the inventors of the birth control pill who has said the contraceptive he helped create was responsible for a 'demographic catastrophe'" (Church grabs chance to attack birth control, 7 January).

Let me pounce back on this statement, which in the meantime has escalated throughout the Catholic press in the US, Italy and elsewhere under such headlines as "Pill inventor slams pill" and "Co-inventor of birth control pill now calls it a catastrophe".

This calumny was prompted by a long article I published in the Austrian newspaper Der Standard on 13 December, where I decried the dramatic shift to the right in Catholic Austria's recent election and its startlingly xenophobic overtones. Given that this happened on the 70th anniversary of the Anschluss, I as a former refugee from Austria - a country that has recently placed my face on a postage stamp - felt obliged to speak out.

Contraception, birth control, abortion, or the pill were nowhere mentioned in my article. I accused the disturbingly large xenophobic segment of Austrian voters (notably young ones) of assuming that their small country was not situated in the middle of Europe but rather on an island where God permits them to live independently to enjoy their schnitzels.

I warned against an impending demographic catastrophe. Without immigration, a country requires 2.1 children per family to maintain its population level; so those xenophobic Austrians would have to have at least three children (which I considered totally unlikely) in order to raise the small size of most of their compatriots' families to a national average of 2.1.

I drew attention to Bulgaria, a country to which I fled in 1938 from Nazi Austria, and which possesses roughly the same current population, age distribution and average family size (1.4 children) as Austria. Nobody these days wants to emigrate to Bulgaria, in contrast to Austria or other western European countries. As a result, demographic estimates predict a 35% drop in Bulgaria's current population by 2050.

I also indicated that Germany's family size (1.3 children) requires an annual immigration of 200,000 just to maintain the current population. Consequently, I emphasised the need in Austria for continuing immigration.

To assume that I attributed the decline in Austria's family size (matched by all-Catholic Italy and Spain) to the pill is absurd. People don't have smaller families because of the availability of birth control, but for personal, economic, cultural and other reasons, of which the changes in the status and lifestyles of women during the last 50 years is the most important. Japan has an even worse demographic problem than western Europe, yet the pill was only legalised there in 1999 and is still not used widely.

One only needs to read my 2001 memoir, This Man's Pill: Reflections on the 50th Anniversary of the Pill, to find my personal views on contraception, the pill, and the de facto separation of sex and reproduction - which sooner or later the Catholic church must face realistically and humanely.

• Carl Djerassi is an author and playwright and is emeritus professor of chemistry at Stanford University. His most recent book (2008) is Sex in an Age of Technological Reproduction
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