Conjoined twins Amelia and Allison Tucker have spent all eight months of their little lives inside the Children's Hospital of Philadelphia. And now, after enduring a complex, seven-hour procedure that required 40 surgeons, the twins — who were joined at the lower chest and abdomen and shared their chest wall, diaphragm, pericardium, and liver — have been successfully separated and may soon be able to leave the hospital and go on with their lives. Conjoined twins are exceptionally rare, occurring in 1 out of every 200,000 live births. Surviving a surgical separation is also highly unlikely, with hospitals seeing a success rate between 5 and 25 percent. But there is hope for the Tucker twins yet, as formerly conjoined brothers and sisters from all over the world have prospered after their dramatic operations. Here, a look at other miracle babies who beat the odds: 

1. Rital and Ritag Gaboura
The Sudan-born twin girls were joined at the head, a defect that occurs in about 1 in 2.5 million births, which posed a particular surgical challenge. Because Ritag's heart provided most of the blood for both her and her sister, the girls were given "10 million-to-one" odds of survival. The surgery took place in four stages in mid-2011; the girls underwent two operations in May and, one month later, tissue expanders, which would help to stretch the babies' skin over their heads, were inserted. In August, the final separation occurred and the 1-year-old girls showed no adverse reactions. They have since been outfitted with special helmets that will help to shape their heads as they grow.

2. Joshua and Jacob Spates
The 8-month-old boys may had always been joined together, but neither had laid eyes on the other, as they were fused together back-to-back at the pelvis and lower spine. Before their scheduled operation, a team of 34 doctors, nurses, and technicians planned for weeks, including practicing on two sewn-together Cabbage Patch Kids. Finally, on August 29, 2011, after a 13-hour operation, the two Memphis-born brothers emerged healthy, happy, and separated. Although it's still unclear if the boys will ever be able to walk on their own, and while they have a long road ahead — male conjoined twins have even less of a chance of survival than their female counterparts — doctors say the boys' future is bright and they are already learning to crawl.

3. Angelica and Angelina Sabuco
The Philippine-born twin sisters were joined at the chest and abdomen and shared livers and diaphragms. On November 1, 2011, the 2-year-olds, who now live with their parents and 10-year-old brother in San Jose, Calif., endured a nearly 10-hour surgery by a team of 20 doctors who both separated and reconstructed the area where the girls had been fused. After the surgery, the girls flourished and within two weeks had normally functioning livers, were off pain medication, and were able to leave the hospital at Stanford University in Palo Alto to begin outpatient therapy. "Balance is the biggest challenge," said their physical therapist who is helping the girls learn how to walk forward and backward with small, supported steps.

4. Trishna and Krishna 
The odds seemed completely against these Bangladeshi-born girls. With only months, if weeks, to live, the twins, who were born joined at the head, were saved from a Bangladeshi orphanage five years ago by their guardian Moira Kelly. In 2009, at almost three years of age, the twins underwent a 27-hour operation performed by up to 16 surgeons at the Royal Children's Hospital in Melbourne, Australia. While the girls were given just a 25 percent chance of making it through the surgery alive, they showed signs of health soon after. And today the twins, who live with their guardians in Melbourne, continue to grow and thrive. While Krishna is developing slightly slower than her sister — she has to be fed through a tube — she is also enrolled in a swimming program, physiotherapy, and speech lessons. Trishna is already looking forward to starting school next year.

5. Hassan and Hussein Benhaffaf
The Irish boys, who were joined from the pelvis to the chest, were given only a 2 percent chance of survival after their birth in December 2009. While the twins each had their own heart, the organs shared the same safety "sac," making the separation all the more dangerous. In addition, the boys, who have only two legs between them, had to have their liver, gut, and blatter separated as well. But in April 2009 a team of 20 medics, including four surgeons and four anesthetists working in shifts, operated on the infants for 14 hours. While Hassan and Hussein were expected to spend up to four months in the hospital, the boys were discharged in less than seven weeks. And now, thanks to replacement limbs created by the world's leading prosthetist, the boys are learning to walk on their own. "Every time I see them raising their legs," said their mom, "it's like watching someone win the Olympics."

6. Eustocia and Eaustina Bosin
The 15-year-old twins from Papua New Guinea lead such normal lives that they never even knew they were anything but separate, identical sisters. It was only in 2011 that the girls, who traveled to Australia where their initial surgery took place, were finally told that they had been conjoined as babies. At just 16 days old, Eusotocia and Eaustina, who were fused from the chest to the navel, with livers attached, were flown to Royal Children's Hospital in Melbourne and separated. Their parents said they decided not to tell their daughters they were conjoined to give them as normal a childhood as possible. Upon their 2011 return to Melbourne, the healthy teenagers had an emotional reunion with their now-retired surgeon, Alex Auldist, who showed them a video of their life-changing surgery.

7. Amelia and Allison Tucker
Considering the successes of the aforementioned twins, Amelia and Allison Tucker seem to have plenty to look forward to. On top of that, their surgery at the Children's Hospital of Philadelphia was the 21st time surgeons there had separated a pair of conjoined twins. "We expect that, with this complex surgery behind them, Allison and Amelia will receive the care, therapy, and support to allow them to live full, healthy, and independent lives," said Dr. Holly L. Hedrick, the pediatric surgeon who led the 40-person team that operated on the girls.