Prematurity is a significant burden for the affected babies, families, and society. In 2018, over 25 thousand babies were born in the USA at less than 28 weeks of gestational age. This article will concentrate on newborns born at 27 and 28 weeks. I will talk about their short-term and long-term outcomes, including physical characteristics and survival rates.
Please treat information here only for educational purposes, as medical knowledge changes quickly, and your situation as a parent may require individualized counseling.
What are the survival rates for babies born at 27 and 28 weeks?
The authors of a study from 25 US hospitals that provided neonatal care to over 115000 women between 2008 and 2011 stated that the survival rate for newborns born at 27 and 28 weeks was 91.8% and 98% (Reference 1). Another set of data covering the years 2008 to 2012 cited the survival rates as 91% for babies born at 27 weeks and 93% for newborns born at 28 weeks (Reference 2).
There are a few things to keep in mind. First, the data comes from major American hospitals and may not be transferable to other countries. In addition, other countries’ populations, economic structures, and health systems may differ significantly from America’s.
Also, those are just average numbers. Suppose you are pregnant and about to deliver a baby prematurely. Your risks may be much higher or lower than known from the cited studies above. That’s why it is so important always to have a conversation with your obstetrician or neonatologist about your specific risks and chances for your baby’s survival.
Physical appearance and measurements for babies born at 27 and 28 weeks of gestational age
Tables 1 and 2 provide expected average measurements for babies born at 27 and 28 weeks. I want to point out that boys tend to be heavier and longer than girls. However, girls are usually better at fighting their health conditions, and their outcomes in terms of survival tend to be more favorable than boys’ (Reference).
Table 1: Measurements in girls born at 27 and 28 weeks and at their due date at 40 weeks for comparison.
| Weeks at birth | Weight in kg | Weight in lb | Height in cm | Height in Inch |
|---|---|---|---|---|
| 27 weeks | 0.9 kg | 1 lb 15.7 oz | 34.5 cm | 13.6 inch |
| 28 weeks | 1.0 kg | 2 lb 3.2 oz | 36.0 cm | 14.2 inch |
| 40 weeks | 3.4 kg | 7 lb 7.9 oz | 50.5 cm | 19.9 inch |
Table 2: Measurements in boys born at 27 and 28 weeks and at their due date at 40 weeks for comparison.
| Weeks at birth | Weight in kg | Weight in lb | Height in cm | Height in inch |
|---|---|---|---|---|
| 27 weeks | 0.95 kg | 2 lb 1.5 oz | 35.0 cm | 13.8 inch |
| 28 weeks | 1.10 kg | 2 lb 6.8 oz | 36.5 cm | 14.4 inch |
| 40 weeks | 3.60 kg | 7 lb 14.9 oz | 51.0 cm | 20.1 inch |
What are health problems encountered by babies born at 27 and 28 weeks in NICU?
Babies born at 27 and 28 weeks missed 12 to 13 weeks of the maturation process that should have occurred in a friendly environment of their mothers’ bodies. So I am sure it is no surprise that all of them have to be admitted to the NICU due to the need for lengthy treatments.
Twenty-seven-weekers usually need to stay in the NICU for 68 days, and 28-weekers require 58 days. In other words, they need to stay in the hospital until they reach the corrected age of 37 weeks. They receive diagnostic evaluations and treatments for different health conditions found in very premature babies during that time.
Below, I will provide information about those ailments, their incidence, severity, and outcomes. The majority of statistical data cited here comes from the following two articles: reference article 1 and reference article 2.
Respiratory Distress Syndrome (RDS)
Respiratory Distress Syndrome (RDS) is the most frequent pathology among premature babies who develop breathing problems right after birth. It is due to their lungs’ anatomical, functional, and chemical immaturity. Premature lungs have fewer alveoli (smallest aerated parts of the lungs) and lack an adequate amount of Surfactant. Surfactant is a substance built of some lipids and proteins that keeps alveoli and lungs from collapsing at the end of exhalation.
We treat RDS with different forms of respiratory support, including the flow of air with oxygen (by nasal cannula) or placing babies on CPAP and ventilator machines. CPAP machines provide extra pressure to babies while they continue breathing independently. In some cases, we can avoid putting a baby on ventilators thanks to that therapy. In other situations, we use CPAP therapy after taking the baby off a ventilator.
According to data, most babies born at 27 and 28 weeks receive CPAP support (over 80%).
Ventilators are capable of doing all breathing work for the babies if it is needed. However, it is the most aggressive form of therapy and involves breathing tube placement into their mouth and lungs. Approximately 81% of 27-weekers and 71% of 28-weekers are placed on ventilators during their NICU stay.
While we have a breathing tube placed, we can also administer to some babies medication called Surfactant (the same substance that premature babies lack in sufficient amounts in their lungs). In a population of babies from 2008-to 2012, 73% of 27-weekers and 65% of 28-weekers received Surfactant treatment.
We can treat RDS successfully in most premature babies; however, in some, this condition evolves into another chronic disease of the lungs called Chronic Lung Disease or Bronchopulmonary Dysplasia.
Bronchopulmonary Dysplasia (BPD) in babies born at 27 and 28 weeks
According to the data, 36% of 27-weekers and 24% of 28-weekers develop chronic lung disease, also called BPD. There are controversies about how to define what BPD actually is. However, the simplified definition is the statement that babies will be diagnosed with BPD if they require supplementary oxygen to keep their oxygenation levels within normal limits at the corrected postconceptual age of 36 weeks.
BPD may be mild when the baby needs “just” some additional oxygen flow delivered by a plastic nasal cannula for a few extra weeks.
Treating a baby with BPD using a ventilator or home oxygen therapy would be rare for these gestational ages (27 and 28 weeks).
Jaundice of prematurity – Hyperbilirubinemia
Jaundice is a condition characterized by yellowish skin and elevated bilirubin levels. I will not focus on this condition here as it is relatively benign for most babies, and I have already written several articles that you can find on my website: article 1 and article 2.
However, you should know that almost all premature babies born at 27 and 28 weeks will have some degree of jaundice, and the vast majority will receive phototherapy for that (light therapy).
Anemia
Anemia is a condition in which a patient has an abnormally low number of red blood cells. Red blood cells are a crucial component of our blood responsible for carrying oxygen to all tissues from the lungs.
Premature babies born at 27 and 28 weeks have only a total blood volume of about 2.3 oz. There are two significant factors contributing to anemia in these babies. The most important probably is the need to subject those babies to frequent blood draws to monitor their wellbeing. The second factor is that their bone marrows are not very good or efficient at producing new red blood cells.
Ultimately, some babies who develop severe anemia need blood transfusions and receive supplemental iron in their nutrition to treat it.
Apnea of Prematurity
A baby suffers from apnea when they stop breathing for 15-20 seconds or shorter duration if that episode is associated with a drop in their heart rate or oxygenation levels. Apnea may be a sign of other medical conditions such as infection, anemia, reflux, or bleeding in the brain.
When other conditions are ruled out as a cause of apnea, we say that baby has apnea of prematurity. This is because babies have irregular breathing patterns due to their brain immaturity and small airways, which are prone to obstruction.
The majority of babies born at 27 and 28 weeks will have some degree of apnea of prematurity. As a result, many of them will be treated with medication that stimulates their breathing called Caffeine. However, if apnea does not respond well to Caffeine treatment, sometimes we have to use different forms of respiratory support (nasal cannula, CPAP, or ventilator) even if a baby does not have any lung disease anymore.
Fortunately, almost in all cases, apnea resolves by 36 weeks of corrected postconception age.
Necrotizing Enterocolitis (NEC)
Necrotizing Enterocolitis (NEC) is a pathologic condition of the intestines, mainly occurring in premature babies. It often involves inflammation, infection, and death (necrosis) of the intestinal wall. It may lead to intestinal perforation, generalized sepsis, and even death in the most severe forms.
Approximately 9% of babies born at 27 and 28 weeks will develop NEC during their NICU hospitalization. After NEC is diagnosed, we have to stop feedings for at least 7-10 days, give long courses of antibiotics, and in more severe cases, doctors perform abdominal surgery to resect dead intestines or repair perforated bowels. You will find more details about NEC in my article here.
Immature Feeding Skills
All premature babies born at 28 weeks or earlier will lack effective oral feeding skills. They usually can suck on a pacifier, but they can never eat by mouth right after birth. Simply, their suck is weak, and they do not know how to coordinate sucking, swallowing, and breathing, so they would not aspirate milk into their lungs.
During the first few days when they are unstable, we provide all necessary nutrition with intravenous fluids. Later we use feeding tubes to deliver breastmilk or specialized formula directly into their stomach.
The feeding skills start maturing around 32 weeks. At that time, we will begin transitioning from tube feedings to oral feedings. It is always a process, and it may take until 35 or 36 weeks before the baby can take adequate volumes of milk by mouth. Of course, every baby is different, and timelines may vary.
Retinopathy of Prematurity
Retinopathy of prematurity (ROP) is an eye condition that occurs due to abnormal blood vessel growth in the light-sensing eye membrane (retina). It may lead to visual acuity impairment or even blindness in severe forms.
There are five stages of the disease. Stages 1 and 2 are milder forms. Stages 3-5 are moderate to severe conditions. Stage 5 is characterized by retina detachment and will result in partial or complete blindness.
According to statistical data, about 44% of 27-weekers and 33% of 28-weekers will have ROP. However, the more severe stages, such as stage 3 or higher, occur only in 4% of 27-weekers and 1% of 28-weekers.
All premature babies born at 27 and 28 weeks receive regular eye exams to diagnose ROP early. Management of ROP includes close observation and, for certain indications, treatment with medicine injected directly into the eye or laser surgery. Even babies who resolved ROP successfully, will require close follow up after discharge to look for such eye problems as myopia or strabismus.
Intraventricular Hemorrhage (IVH)
Brains of babies born before 32 weeks of gestation are prone to bleeding. The hemorrhages inside their brains occur due to immature and brittle blood vessels and sudden blood pressure changes in sick babies. There are four stages of IVH, with stages 3 and 4 being the most severe and consequential for the future neurodevelopment of babies. It is estimated that about 6% of 27-weekers and 3% of 28-weekers may develop grade 3 or 4 IVH during their hospitalization in NICU.
Doctors diagnose IVH by performing intracranial ultrasounds (head ultrasound – HUS). We usually do HUS on all babies born before 32 weeks within seven days after birth. The study can be performed at bedside, and results are available immediately. If IVH is present, we repeat HUS periodically to follow its resolution or progression to hydrocephalus.
Hydrocephalus may require surgery to treat. IVH is not that common among babies born at 27 and 28 weeks; however, its diagnosis is essential as it can be associated with less favorable future development in affected children.
Sepsis or Infections
Premature babies are at risk for infections (generalized infection is also called sepsis). The chances of infections are elevated due to the following factors:
- Mothers provide antibodies (antibodies = chemicals that fight infections) to their babies during the last three months of pregnancy. Since 28 and 27-weekers are born 12-13 weeks earlier, they do not receive that benefit.
- Often, maternal infections are the reason for early birth. Therefore, maternal infections may be passed to the babies endangering them.
- Premature babies require aggressive forms of treatment, which involve placing various tubes, needles, and catheters in their bodies. Unfortunately, those ‘foreign instruments” pose a tremendous risk for infections.
- Newborns in NICU are attended by numerous medical specialists, nurses, and family members who themselves may carry and pass infections to little patients.
Our approach to infections in premature babies is to do lab tests if you suspect an infectious disease and treat it right away without waiting for confirmation. This is because it takes time for any test to prove an infection, and it would be too dangerous for tinny babies to remain untreated during the wait time.
Infections can kill tiny babies quickly. As a result, we give at least one course of antibiotics to most sick premature babies. At the same time, data tells us that “only” about 17% of 27-weekers and 13% of 28-weekers develop proven infection (by culture test) during their hospitalization in NICU.
What is the long-term development of babies born at 27 or 28 weeks of gestational age?
Parents of premature babies usually have three fundamental questions for their doctors soon after delivery. 1. Will my baby survive? 2. When will my baby be able to go home? And how is my baby going to do in the future?
Let’s try to answer the last question here. The closest data set that reflects our babies of interest (27 and 28-weekers) comes from the article published by Veronique Pierrat. The study covers over 5500 babies born in France in 2011 at a gestational age between 22 and 34 weeks.
We will look more closely at the subgroup of babies born between 27 and 31 weeks. For that subset of babies, researchers reported a 4.3% rate of cerebral palsy. In addition, about 90% of babies survived without any significant neurodevelopmental or sensory (blindness, deafness) disabilities. One note of caution here. Since this particular data pools together babies born at 27-31 weeks, if we want to find out only the values of these outcomes for younger babies (27 and 28-weekers), we need to extrapolate these numbers a little to a less favorable tail (Reference).
If you are a parent of a premature baby born at less than 32 weeks and your baby is in NICU right now, you may also be interested to read my book: “Babies Born Early.”
Conclusions:
In summary, I want to emphasize that babies born at 27 and 28 weeks are immature at birth and will have to undergo two months of treatment in the NICU. However, their survival in developed countries is at least 90% or better, and despite many complications encountered in NICU, the majority of them will do quite well as children and adults.
Disclaimer:
This article is only for general information purposes. It should not be viewed as any medical advice. In addition, there is always a chance that the information here may be inaccurate. Therefore, it would be best for you to always discuss health-related matters with your doctor before making any decisions that may affect your or your family member’s health.