Later in the day, mother and daughter were expected to be reunited for the first time since Sunday's birth.
Adriana Iliescu, who was artificially inseminated using sperm and egg from anonymous donors, delivered her daughter Eliza Maria by Cesarean section, doctors at the Giulesti Maternity Hospital in Bucharest said. The child's twin sister was stillborn, they said.
"The child is eating a bit of glucose," hospital spokeswoman Mirela Ranga said Monday. "Mrs. Iliescu is still in intensive care, but she is moving around. She is expected to go see her daughter a bit later."
News of the birth has sparked debate in Romania over the ethics of women beyond the age of fertility having babies. One church official said it was shocking.
Iliescu sat up in her hospital bed Monday and told Associated Press Television News she was "more than happy" to have given birth. She had undergone nine years of fertility treatments before being inseminated, said Dr. Bogdan Marinescu, who runs the hospital.
AP video of Eliza Maria showed her squirming in an incubator. She was dressed in a pink and white bodysuit with a pale pink woolen hat. Doctors said she was breathing on her own.
The child was born more than six weeks short of a full 40-week pregnancy, the hospital said. She weighed just 3.19 pounds, less than half the weight of an average newborn and was in the intensive care unit.
Doctors performed the Cesarean section after the smaller of Iliescu's twins died in the womb, Ranga said. That child weighed just 1.54 pounds, she said.
Marinescu said Iliescu was successfully inseminated on the first attempt, and that she initially was carrying triplets but lost the third fetus after nine to 10 weeks.
Marinescu has declined to comment on ethical questions regarding the pregnancy, but said he was impressed by Iliescu's faith in God and her determination to have a child.
"She was in the right condition to carry a pregnancy," he said.
Bishop Ciprian Campineanul, a member of the Orthodox Church's bioethics committee, said clerics disagreed in principle with in vitro fertilization whatever the woman's age.
"This case has shocked us all," he said. "This was a selfish act."
Daniel Muresan, a gynecologist and university professor in the northwestern city of Cluj called Iliescu and her doctors brave but said he would not encourage similar births.
"It should remain an exception. It is at the limit of ethical guidelines because it is at the limit of nature. ... We all get old. Healthwise, it is risky for both the mother and the child who deserves to have parents to raise her," Muresan said.
The Health Ministry said in a statement Monday it would offer its full support to the mother and the baby but would not encourage artificial insemination of women who are no longer fertile.
There is no law in Romania stipulating a maximum age for artificial insemination. A draft law awaiting approval in parliament bans fertility treatment for women who are above the normal reproductive age.