Same-sex couples will be given the same rights as heterosexual couples under guidance issued by the National Institute for Health and Clinical Excellence.
The NHS will also extend the upper age limit for IVF by three years to 42, following advice that suggests many women in their late 30s and early 40s could conceive after treatment.
The move will see thousands of women a year given the chance to become mothers without having to pay up to £8,000 to private clinics.
Fertility experts also questioned whether health authorities could afford to widen eligibility criteria, when only a quarter currently fund three cycles of IVF for infertile couples, as recommended by Nice.
[Related article: Top foods for enhancing fertility]
Gedis Grudzinskas, emeritus professor of obstetrics and gynaecology at Barts and the Royal London Hospital, said that while the new guidance reflects "social changes" there were questions over whether NHS trusts could afford it.
"How do we reconcile the changes in society and equality of access to healthcare, with the economic predicament?" he said.
The new guidelines call on health authorities in England and Wales to fund fertility treatment known as intra-uterine insemination (IUI), using donor sperm, for people in same-sex relationships.
If they fail to conceive after six cycles of IUI, they should be considered for in-vitro fertilisation (IVF), which is much more costly and involved.
The move follows a relaxation in the law, made under Labour in 2008, to put same-sex parenting on an equal legal footing.
The recommendation follows implementation of the Human Fertilisation and Embryology Act 2008. It abolished requirement for fertility clinics to take into account a child’s need for a father or a male role model before agreeing to treatment. Gay couples or single women now need only show they can provide "supportive parenting".
Demand from gay couples paying privately for fertility services has subsequently boomed, say clinics.
Official figures show the number of lesbian couples undergoing IVF rose from 178 in 2007 to 417 in 2010.
One cycle of IVF can cost up to £8,000 privately. Because success rates are low - typically 20 per cent for a 38-year-old - couples can spend tens of thousands on treatment.
Gay rights campaigners welcomed the proposal, saying many same-sex couples receive "outright discrimination" from health authorities, but others said it amounted to a Government-backed attempt to "rewrite biology"
Josephine Quintavalle, founder of Comment on Reproductive Ethics, described the same-sex move as "absurd".
She said: "We are not prepared to accept what constitutes fertility from a biological perspective.
"Fertility treatment is very important but in this case what we are trying to do is rewrite biology."
Under the Nice guidelines, women aged 40 to 42 deemed to have no chance of conceiving naturally should be offered one full IVF cycle. In this age group one in eight will give birth after one cycle.
Adam Balen, professor of reproductive medicine at Leeds Teaching Hospitals, and a senior member of the British Fertility Society, said it would increase demand for NHS-funded fertility services, although not by much in the short term.
He said same-sex couples were "still a relatively small proportion of patients in clinics such as mine".
Ruth Hunt, director of public affairs at Stonewall, the gay rights charity, welcomed the consultation as "explicit acknowledgements of the issues same-sex couples face".
Sir Andrew Dillon, chief executive of Nice, told BBC Radio 4’s Today Programme he believed it was important for the NHS to do the “right thing” in supporting older women who need IVF to conceive.
He said: “It’s really important we know what the right thing to do it. The NHS needs a national point of reference when it's making decisions, especially regarding treatments which we know that in some areas is not treated as a priority.
“The focus of the guidelines has been to encourage the NHS to do more. Providing more information and extending the range of circumstances where it is appropriate for the NHS to help will continue that trend.
“The NHS has made a commitment to support people having difficulties conceiving. It’s important we know what the right thing is to do.”
He told the programme he agreed it was right for people who want to undergo IVF to have access to it through the NHS, and that lifestyle choices should only be taken into account if they had a proven impact on the success of treatment.
“I believe it’s right for the NHS to provide these services when the cause is medical and it’s clearly possible for us to do something and it could be effective,” he said.
“I think lifestyle is only appropriate in circumstances where that has material impact on the likelihood of success. We should start with what’s right.”
The programme also heard from Justine Bold, a woman who's spent more than £33,000 on fertility treatment at 43, who said there was still a “postcode lottery” for treatment.
She said: “Unfortunately the changes would not help me but I hope they will help other women. It’s still a postcode lottery.
“It’s been a long journey. It’s very hard, socially isolating and financially it’s very stressful as well.
“At the moment it’s just guidelines. It doesn’t mean there’s an obligation for commissioners or PCTs to fund treatment.
“You come across the attitude that infertility is not life-threatening and should not be treated, especially during times of austerity, which I think is ridiculous.”