A 61-year-old United States woman who carried a baby for her son and his husband said that serving as a surrogate was a "gift" to the gay couple.

Key points: Doctors carefully checked Cecile Eledge's health before approving the surrogacy

Doctors carefully checked Cecile Eledge's health before approving the surrogacy The 61-year-old gave birth to her healthy baby granddaughter, Uma, two weeks ago

The 61-year-old gave birth to her healthy baby granddaughter, Uma, two weeks ago Uma was conceived using in vitro fertilisation

Cecile Eledge and her family did not think doctors in her Nebraska hometown would allow her to act as a surrogate because of her age.

But two weeks ago she gave birth to Uma Louise Dougherty at the Nebraska Medical Centre in Omaha in a natural delivery.

"I wanted to do it as a gift from a mother to her son," Ms Eledge said.

The circumstances of Uma's birth are a testament to changing social mores as well as the dramatic advances in senior health made by modern medicine and healthy lifestyles.

Ms Eledge volunteered to be the surrogate mother to her grandchild, conceived with sperm from Mr Eledge and an egg from Mr Dougherty's sister, Lea Yribe. ( AP: Ariel Panowicz )

On social media, the family was inundated with messages, most of which were positive but some were extremely angry and negative, Cecile's son Matthew Eledge said.

"People from all around the world have been reaching out," he said. "They want to help in any way that they can."

The family is trying to ignore the negative reactions, such as the people who wrongly think that Mr Eledge had sex with his own mother to produce the baby, or who leave homophobic remarks.

When they set out to start their family, Mr Eledge and Elliott Dougherty believed they would be denied permission to adopt a baby in their conservative home state so decided to try in vitro fertilisation using a donated egg and a surrogate to carry the foetus.

Mr Dougherty's sister, Lea Yribe, offered to donate her eggs. The eggs were fertilised with sperm from Mr Eledge, giving Uma genetic material from both sides of the family.

The men jokingly told their IVF doctor that Mr Eledge's mother had offered to be the surrogate, even though she was at that point 59 and had gone through menopause.

Doctors in Nebraska say they were not deterred by the politics of helping the grandmother act as a surrogate for a gay couple. ( AP: Ariel Panowicz )

"Matt would comically say, 'Well my mom keeps offering but we know that's not an option,'" Ms Eledge said.

Among possible complications for older mothers are gestational diabetes and high blood pressure, and the medical team monitored the high-risk pregnancy carefully.

Carl Smith, a specialist in maternal and foetal medicine at the medical centre, said Ms Eledge was healthy and fit, and looked years younger than her age.

Ms Eledge took estrogen supplements for the first part of the pregnancy, Dr Smith said, until the placenta holding Uma was able to make hormones of its own.

The politics of helping a gay couple and the unusual choice of a grandmother for a surrogate did not deter the team, Dr Smith said.

"We never gave that a second thought," Dr Smith said. "She was pregnant and the circumstances of how she got pregnant are between her and her family."

Reuters