Conjoined twins are two babies that are born connected to each other. Typically, this happens when the cells of identical twins fail to completely separate in the womb, and two babies develop while they’re still fused together. After a Minnesota mother received a wave of media attention for the tragic loss of one of her two conjoined girls after an agonizing 5-hour surgery, a closer look at the life and struggles of conjoined twins is indeed warranted.

According to the Mayo Clinic, conjoined twins can come in all types and configurations. Some of them share internal organs, while others are connected simply by skin and muscle tissues. Most commonly, conjoined twins are connected at the chest, pelvis, or buttocks.

Conjoined twins are extremely rare, occurring in roughly one out of every 60,000 pregnancies. As such, there is little scientific data available outlining the risks faced by conjoined twins. Despite this lack of data, empirical evidence suggests that a slew of complications can arise for twins that share internal organs and sections of the nervous system.

The majority of conjoined twins are stillborn, but on rare occasions they make it out of the womb alive. Sadly, of the conjoined twins that survive, fewer than half live long enough before they can be considered for separation surgery.

For the rare few conjoined twins that survive separation, life can be tough. Since there are so few other conjoined twins in the world, these people often report feelings of isolation and being misunderstood. Parents must deal with the stress of being uncertain about their children’s health, and the grief that follows losing a child must be unimaginable.

In the case of Amber McCullough, the Minnesota mom that recently lost a daughter to separation surgery, the twins shared too many internal organs for both of them to survive. McCullough opted to give her surviving daughter the best chance at a normal life as possible.