Susie Kozisek of Ventura, Iowa recently gave birth to her daughter’s twins.
Pregnancy would be dangerous for Ashley Larkin, Kozisek’s daughter, because she has a heart condition called pulmonary hypertension.

Pulmonary hypertension is a heart condition that also affects the arteries in the lungs. The Mayo Clinic describes this condition here .

"I just felt really privileged and honored to be able to help," Kozisek told local news source Sioux City Journal. . "I think everybody would do whatever they can do for their children."

This is the second time that Susie has carried a baby for her daughter. Susie gave birth to a granddaughter named Harper in 2011.

"It's usual for a mother to act as a gestational carrier for her own child and she was at the older end of the spectrum for pregnancy," Dr. Jani Jensen told ABC News . "But she [Kozisek] was a good candidate because she'd carried previous pregnancies successfully and was in excellent health."

Koziesk was a gestational carrier, not a surrogate, for both pregnancies because doctors used Ashley’s eggs in both times.

"Patients who have medical conditions that make pregnancy risky or impossible need gestational carriers, and very few are fortunate enough to have family willing to do so," Dr Jensen told the New York Daily News . "Usually it's the sister or sister-in-law."