LONDON - Opposite-sex Marriages in Britain have fallen to their lowest number on record, the Office for National Statistics (ONS) said in an annual report Wednesday.

An analysis of marriages in England and Wales for 2015, the last full year reviewed, show that there were 239,020 marriages between men and women, a fall of 3.4 percent compared to the previous year. It was the first full calendar year during which same sex marriage was allowed.

The number of marriages in 2014 was higher than the previous year but ONS said this could have been couples delaying marrying in 2013 to avoid the number 13, considered by many to be unlucky.

Marriage rates for opposite-sex couples in 2015 were the lowest on records that date back to 1862, with 21.7 marriages per thousand unmarried men and 19.8 marriages per thousand unmarried women, said ONS.

In the same year the number of couples opting for religious marriage services fell by 8 percent, compared with 2014.

In 1900, religious ceremonies accounted for 85 percent of all marriages, by 1980 this had fallen to 50 percent. Since 1992, civil marriages have increasingly outnumbered religious marriages every year, added ONS.

Changes in Britain's matrimony laws mean ceremonies can now be performed in historic buildings, hotels and other venues.

Among opposite-sex couples, more women than men married at ages under 30 while over the age of 30 more men married. This pattern, said reflects that on average men tend to form relationships with women younger than themselves.

In 2015 there were 6,493 marriages between same-sex couples, 56 percent of them between female couples. A further 9,156 same-sex couples converted civil partnerships into a marriage.

There were only 44 religious marriage ceremonies of same-sex couples, accounting for 0.7 percent of all marriages of same-sex couples, added ONS.

ONS statistician Nicola Haines said: "This is the first full year for which marriages were available for same-sex couples and they accounted for 2.6 percent of all marriages."

Numbers marrying during World War II before steadily climbing in the post-war era. But it had never reached the 1940 peak when there were 470,000 weddings. The last peak was in 1972 when 429,000 couples married, and since there has been a steady decline.