The word ‘marriage’ has vanished from Government statistics on conceptions.
The official figures instead lump marriages and civil partnerships together under the label “legal partnership”.
The new figures show there were around 900,000 conceptions in England and Wales in 2009. Background notes reveal that only 218 of those were attributed to someone in a civil partnership.
The Office for National Statistics (ONS), which released the information, said for birth and conception statistics it “does not distinguish between civil partnerships and marriages”.
The move is likely to concern those who point to evidence of the benefits of the institution of marriage.
The controversial Human Fertilisation and Embryology Act 2008 allowed homosexual couples to be jointly named on birth certificates.
The change came into force for any children conceived by someone in a homosexual relationship after 1 April 2009.
In 2003 Labour ministers said they wanted to see the word “marriage” no longer used on official documents, claiming it led to discrimination against homosexuals.
Last month Iain Duncan Smith, Secretary of State for Work and Pensions, said his department would reintroduce references to marriage on official forms and pieces of research.
In April last year two lesbians became the nation’s first homosexual couple to jointly sign a child’s birth certificate as parents.
Natalie Woods and Elizabeth Knowles jointly signed the birth certificate at Brighton Register Office after Miss Woods conceived via a sperm donor.
Critics expressed alarm at birth certificates being tailored in such a way.
Baroness Deech, the chair of the Bar Standards Board, which regulates barristers in England and Wales, warned that such birth certificates could undermine the child’s right to understand their identity.
Speaking in March 2010 Lady Deech insisted: “There is an issue of principle here, which is the truth”.
She added: “It puts the demands of the adults ahead of the rights of children to know and benefit from both sides of their genetic makeup.
“This is not a moral issue; it is about disguising true facts, and it is about confusing biological parenthood, legal and social parenthood.”
And Josephine Quintavalle, from the campaign group Comment on Reproductive Ethics, said: “Birth certificates should reflect how a baby is generated.
“In a culture that is obsessed with genetics, it is strange that when it comes to birth certificates we are prepared to forget all that.
“As much as you try to play around with the terminology, the biology reflects what has happened and one day the child will ask about their father.”