The Tiny Baby Collaborative is an international group established by physicians trying to better understand how to best care for premature infants under 24 weeks of gestation and their families. The Collaborative has two goals: To share experiences among hospitals with expertise in treating preterm infants. To find better ways to care for the most premature babies and their families.

The Tiny Baby Collaborative works to improve outcomes for extremely preterm babies and their families by sharing knowledge among its members and, more broadly, with other hospitals and clinical teams who are interested in improving care for their patients.

The term micropremie is not an official medical term but is sometimes used to describe small premature babies. Small and preterm infants are classified by birth weight or gestational age. Extremely low birth weight infants are infants weighing less than 1,000 grams (2 pounds 3 ounces) at birth. Extremely preterm refers to babies born at less than 28 weeks (usual pregnancy duration is around 40 weeks). These terms were defined in the 1970s, when neonatal medicine was not as advanced as it is today. The Tiny Baby Collaborative focuses on the unique needs of babies born at or before 23 weeks of gestation. There is no official term to describe this group of patients. Until recently, many hospitals around the world did not report survival of babies born this early. However, some hospitals now report that a majority of these patients can survive with specialized care. Further research is needed to better understand how to provide the safest and most effective care for families with babies born this early.

Premature birth has many different causes, but can be grouped into three broad categories: The first, and most common, is when labor starts early. This could be from an infection, premature dilation of the cervix, and many other causes. In many cases, the reason is not known. Second, sometimes an obstetrician recommends early delivery for the mother's health (for example, when her blood pressure is too high and cannot be controlled). Third, sometimes the baby is delivered early because he or she is not thriving and the medical team thinks that, despite prematurity, the baby will have a better chance of surviving outside of the womb. Premature birth for this reason is rare below 24 weeks of gestation.

The more premature a baby is at birth, the smaller the baby and the more immature the function of every body organ. The baby’s small size means the nurses and doctors will have to use smaller breathing tubes, feeding tubes, IVs, and even diapers. In general, the smallest details of care matter most for the smallest babies. In babies born at ≤23 weeks, immature body organs that affect medical treatment compared to babies born just a few weeks later include the developing lungs and the thin, translucent skin. Because of the less mature lungs, doctors may use different ventilators (breathing machines) or operate them differently than babies born a few weeks later. Because of the immature skin, doctors have to take extra care in keeping the babies warm and giving them enough fluid to avoid dehydration. Special care must be taken to avoid damaging the fragile skin.

Survival varies by gestational age and varies by where the baby is born. Also, survival of the most premature babies is gradually increasing over time. No survivors have been described at 20 weeks of gestation. A few babies are known to have survived at 21 weeks. Several hospitals in the Tiny Baby Collaborative report survival >50% for babies of 22 weeks and >70% for infants of 23 weeks. But survival varies widely and, in other hospitals, is generally lower. In low-resource countries, infants born this early are not expected to survive at all. There is very little information available on the long-term health of people born before 24 weeks of gestation. Limited studies indicate that, at some hospitals, about two-thirds of survivors will be free of severe disability at 2-3 years. It is reported that they can talk, walk, and attend regular school. Based on clinical experience, many children are considered to be doing well.

Babies born at ≤23 weeks of gestation are at risk of several serious complications involving the brain, lungs, intestines, eyes, and heart during the weeks and months that they stay in the neonatal intensive care unit before going home. Fortunately, many of these complications are treatable, but some can lead to long-term health problems and even death. After discharge from the hospital, babies born at ≤23 weeks of gestation can face delays in development, problems with strength and coordination, need for oxygen or medicines, and require additional support at school. They should be cared for by clinicians who can provide developmental monitoring and have experience in caring for patients born this early.

The plan for follow-up care depends on each baby’s needs. Some babies need only routine pediatric care and monitoring for normal development. Others need to be followed by multiple specialists and therapists. Generally, babies born at 22 or 23 weeks have had impaired lung development and are more likely to get sick, and to be more severely sick, with common respiratory viruses in early childhood.