A micro preemie is a baby who is born weighing less than 750 grams, or before 26 weeks gestation. Since micro preemies are born months before their due dates, they face long stays in the neonatal intensive care unit (NICU). Although many extremely premature babies grow up with no long-term effects of premature birth, some face severe health problems throughout life.

Premature Baby vs. Micro Preemie

Any baby who is born before 37 weeks gestation is considered to be premature (also known as preterm). The World Health Organization (WHO) defines prematurity based on when a baby is born. Babies born before 28 weeks are considered “extremely preterm.” Those born between 28 and 32 weeks are considered “very preterm.” Babies are considered “moderate” to “late preterm” if they are born between 32 and 37 weeks.

Micro preemies are the most premature babies of all, born on or before 26 weeks. Many people are surprised by how small micro preemies are. Their skin is thin, with visible veins, and it may look sticky or gelatinous. If you are visiting a micro preemie in the NICU, you can expect to see the following:

  • Respiratory support: Micro preemies usually have endotracheal tubes (ET tubes) coming from their mouths. The tube is attached to a ventilator that helps the baby breathe. Some micro preemies can breathe on their own and will be on continuous positive airway pressure (CPAP) instead. These babies will have CPAP masks strapped over their noses.
  • Intravenous lines (IVs): If a micro preemie’s digestive system is too immature to absorb nutrition, they will be fed intravenously. Most will have lines in their umbilical cord stumps (called umbilical lines) for the first week or two of life, and a PICC line or peripheral IV later.
  • Monitoring equipment: All NICU patients are closely monitored. Micro preemies may have wired stickers on their chests, feet, wrists, arms, and legs. These are used to check blood pressure, breathing rates, and oxygen levels in the blood.
  • NG/OG tube: Because micro preemies are too immature to eat from a bottle or from the breast, a tube will go from their mouths (OG tube) or noses (NG tube) into the stomach.

Micro Preemie Health Concerns

When a baby is born very prematurely, they are at risk for a number of health conditions. Some are short-term, while others may impact them for the rest of their lives.

Short-Term Health Concerns

Immediately after birth and during a micro preemie’s NICU stay, doctors and nurses watch closely for several serious medical conditions, such as these.

  • Intraventricular hemorrhage (IVH): IVH is bleeding into parts of the brain. Micro preemies have fragile blood vessels in their brains, and these vessels can rupture easily. About a quarter of micro preemies have serious IVH. Most cases of IVH resolve on their own, but some babies may need surgery to help drain the extra fluid.
  • Necrotizing enterocolitis (NEC): Since micro preemies have immature digestive systems, their intestines are susceptible to infection. In NEC, the linings of the bowels become infected and begin to die. In micro preemies, the condition can be extremely serious. NEC is treated with IV fluids and medication. Surgery may be required.
  • Patent ductus arteriosus (PDA): A PDA is a persistent connection between the large blood vessels near the heart. The connection is normal for a fetus but should close when a baby is born and begins to breathe. PDAs are treated with medication or surgery.
  • Respiratory distress syndrome (RDS): Most micro preemies have difficulty breathing after birth. This syndrome is treated with respiratory support and medication.
  • Retinopathy of prematurity (ROP): The blood vessels in a micro preemie’s eyes are not fully formed at birth. When the vessels develop, they may grow so rapidly that they damage the retina. While some cases resolve on their own, surgery may be required in severe cases.
  • Sepsis: Premature babies are prone to infection for several reasons. Micro preemies have immature immune systems and face many invasive procedures in the NICU, each of which can allow bacteria to enter the body.

Long-Term Health Concerns

Many micro preemies show no long-term effects of prematurity. However, other micro preemies may have lifelong health issues.

  • Cerebral palsy: A portion of micro preemies have moderate to severe cerebral palsy.
  • Chronic lung disease: Many micro preemies need oxygen at NICU discharge. Micro preemies may also have asthma or other respiratory problems, including bronchopulmonary dysplasia, or BPD.
  • Cognitive problems: Developmental delays, trouble in school, and other cognitive problems are common effects of prematurity.
  • Digestive problems: Micro preemies are prone to digestive problems such as gastroesophageal reflux disease (GERD), food refusal, or poor feeding.
  • Vision or hearing loss: A small percentage of micro preemies have permanent vision or hearing problems due to complications of prematurity.

Survival Rate for Micro Preemies

Micro preemies are very fragile, and every day that they can spend inside the womb increases their chance of survival.

Improve Your Baby’s Chances

Although micro premies may face serious health problems, there are many things that you can do as a parent to give your baby the best possible start.

  • Get early prenatal care: When you become pregnant, talk to your doctor early about how to minimize your risk of premature birth. Early prenatal care can help you avoid early delivery.

  • Have your baby in a hospital with a NICU: If you know that your baby will be premature, delivering in a hospital with a level 3 NICU with 24-hour neonatology coverage can give your baby the best possible start.

  • Learn the signs of preterm labor: While you’re pregnant, make sure that you understand the signs of preterm labor, and seek medical care immediately if you develop any of them.

  • Seek early intervention: Babies born early may qualify for state-run early intervention programs. Starting these programs as soon as possible can help minimize any cognitive effects of prematurity.

  • University of Washington. Extremely Low Birth Weight NICU Graduate Supplement to the Critical Elements of Care for the Low Birth Weight Neonatal Intensive Care Graduate (CEC-LBW).

  • World Health Organization. Preterm birth.

  • Nemours KidsHealth. When your baby’s in the NICU (for parents).

  • Stanford Children’s Health. Intraventricular hemorrhage in babies.

  • Nemours KidsHealth. Necrotizing enterocolitis (for parents).

  • Cleveland Clinic. Patent ductus arteriosus (PDA): What is it, symptoms & treatments.

  • National Eye Institute. Retinopathy of prematurity.

  • Sepsis Alliance. Children.

  • Vincer MJ, Allen AC, Allen VM, Baskett TF, O’Connell CM. Trends in the prevalence of cerebral palsy among very preterm infants (<31 weeks’ gestational age). Paediatr Child Health. 2014;19(4):185-189. doi:10.1093/pch/19.4.185

  • Allotey J, Zamora J, Cheong-See F, et al. Cognitive, motor, behavioural and academic performances of children born preterm: a meta-analysis and systematic review involving 64 061 children. BJOG. 2018;125(1):16-25. doi:10.1111/1471-0528.14832

By Cheryl Bird, RN, BSN

Cheryl Bird, RN, BSN, is a registered nurse in a tertiary level neonatal intensive care unit at Mary Washington Hospital in Fredericksburg, Virginia.