More than 60,000 civil partnerships have taken place in the UK since the legislation first came into force, figures from the Office for National Statistics (ONS) show.
The average age of men forming a civil partnership in 2012 was 40, while for women the average age was 37.6.
The average age at which heterosexual men get married is 30.8 years, while heterosexual women are typically aged 28.9 years when they tie the knot.
Over the eight-year period between civil partnership legislation coming into force in December 2005 and the end of December 2012, 60,454 civil partnerships were formed in the UK, equivalent to 120,908 civil partners.
The figure compares with a government estimate in 2004 suggesting a likely take-up of between 11,000 and 22,000 people in civil partnerships in Britain by 2010.
Dissolutions of civil partnerships have increased 20% to 794 from 663 in 2011.
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Civil partnerships in Ireland have only been legal since 2011.
In May, ahead of Royal Assent of the same-sex marriage act, the government announced a review on the future of civil partnerships, designed to start this autumn.
The Department for Culture, Media & Sport (DCMS) told Pink News.co.uk that the review was needed in order to assess the potential impact of the Marriage (Same Sex Couples) Act on civil partnerships.
It is possible the 2014 arrival of same-sex marriage in England and Wales could mean gay couples eventually no longer opt for civil partnerships.
Three Tory MPs – Tim Loughton, Charlotte Leslie and Rob Wilson – pushed for civil partnerships to be an option for heterosexual couples in an amendment as part third reading of the marriage act in May.
The government has so far resisted calls by equality campaigners to extend civil partnerships to heterosexuals.