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Prematurity: Diagnosis and Related Conditions

Prematurity: Diagnosis and Related Conditions
Rhonda Mattingly, EdD, CCC-SLP
May 7, 2018

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Rhonda: It is good to be here today. If you were with me for the first webinar in this series, we discussed the many aspects of typical feeding development. As we concluded, I shared some of those diagnoses and conditions that can disrupt typical feeding progression. One of the diagnoses that I mentioned is prematurity. Prematurity, as a diagnosis itself, can influence developmental outcomes, but it is also related to many other conditions that co-exist that can also impact the child and the family. My intention today is to provide you with current and accurate information about prematurity and the conditions that are associated with it. I will do that by sharing facts about some of the diagnoses and sharing some research about each of the diagnoses and how they impact the child and family.

At-Risk Populations

Let's look at the at-risk populations for prematurity. Who is more likely to have a premature infant?

  • Low income
  • Women of color
  • Women younger than 20; older than 40
  • Women who were born prematurely
  • Women with a history of a previous premature delivery
  • Women with multiple pregnancies
  • Women with uterine/cervical abnormalities

At risk populations include low income, women of color, women younger than 20 and older than 40, women who were themselves born prematurely, women who have had a history of previous premature delivery, multiple pregnancies, and uterine and cervical abnormalities.

Additional Risk Factors for Prematurity

  • Smoking, alcohol, substance use
  • Infection
  • Stress
  • Trauma
  • Unintended pregnancy
  • Chronic health conditions
  • In-vitro conception
  • H/o repeated miscarriages/spontaneous abortions

Medical technology is making it possible now for so many more infants to be born through fertility enhancement. Through fertility drugs and the different procedures, they are now able to help a lot of folks have a baby, but that does not necessarily mean that the uterine environment is ideal. This might have something to do with the higher prematurity rates. This is not terribly well-understood, but I think that is something to bring up. There is also a history of repeated miscarriages and spontaneous abortions. The other piece to this is that a lot of premature infants are surviving that maybe historically would not have. These might be infants with congenital heart defects or some other diagnoses that might not have survived without advances in medical technology.

Incidence of Prematurity

Let's now talk about the incidence of prematurity. It is estimated to be about 11% of births worldwide. That translates to about 15 million preterm infants born each year. To give you an idea of how they break down in terms of age, about 84% of them are 32 to 36-weekers, with term being 37 to 40 weeks. Ten percent are between 28 weeks and less than 32 weeks, and then 5% is less than 28 weeks, so that is 12 weeks early.

Additional Statistics

  • Associated with approximately 1/3 infant deaths in the U.S.
  • Accounts for ~ 45 % of children diagnosed with CP
  • Accounts for ~ 35 % of children with vision impairment
  • Accounts for ~ 25% of children with cognitive & hearing problem

It is associated with approximately a third of the infant deaths in the U.S., 45% of children diagnosed with CP, 35% of children with vision impairment, and 25% of children with cognitive and hearing impairment.

Classification

Looking at classification, research has shown us that the earlier an infant is born, the more short and long-term problems they are likely to have. Those problems can span across all domains, impact lots of physiological functions, and that, of course, is what we are talking about today. I will point out though that more research over the last decade or two has brought to light that even late preterm infants can have considerable trouble. We need to be very cognizant of that. Just because an infant was late preterm does not mean they cannot have problems as well. 

Gestational Age

  • Late Preterm Birth – Between 34 (0/7) and 36 (6/7) Weeks GA
  • Very Preterm Birth – Less than 32 Weeks GA
  • Extremely Preterm Birth – At or Below 28 Weeks

A late preterm infant is between 34 0/7 and 36 6/7 weeks gestational age. Once they hit 37 weeks, they are considered term up to 40 weeks which is full term. Very preterm is less than 32 weeks gestational age, and extremely preterm is at or below 28 weeks. This is just one way of classifying preemies.

Birth Weight

You can also classify them from a birth weight standpoint.

  • Low Birth Weight – birth weight is less than 2500 g
  • Very Low Birth Weight – birth weight is less than 1500 g
  • Extremely Low Birth Weight – birth weight less than 1000 g

The lowest birth rate is the population that has the most trouble. A birth weight of fewer than 1000 grams is about 2 pounds, this is comparable to a can of tomatoes. A very low birth weight infant is less than 1500 grams and that infant would weigh about three pounds. A low birth weight infant is less than 2500 grams, which is about 5 pounds. This is the same as a bag of flour. Other issues can cause lower birth weight, like smoking, so keep in mind that birth weight is not always prematurity. It does have implications in other conditions.

Survival Rates

Due to advances in medical care, more infants are surviving now as compared to previous generations.

  • 22 weeks 6% (1993) to 9% (2012)
  • 23 weeks 28% (1993) to 33% (2012)
  • 24 weeks 52% (1993) to 65% (2012)
  • 25 weeks 68% (1993) to 81% (2012)
  • 26 weeks 83% (1993) to 87% (2012)
  • 27 weeks 84% (1993) to 94% (2012)
  • 28 weeks 91% (1993) to 94% (2012) (Journal of American Medical Association)

In 1993, about 68% of 25-weekers survived, but that shot up to 81% in 2012. If you look at 27-weekers, in 1993 they saved about 84%, but in 2012 they saved 94%. Both of these are nice big jumps. Late preterm infants increased from 7.5% in 1990 to 17.3% in 2006. Advancements are helping these babies survive at a much higher rate than they used to survive, but the outcomes are not really any better at this point. They are able to save them, but we still see a lot of these outcomes that we need to treat.

Adjusting for Prematurity

It is important to consider how prematurity impacts our expectations for a child's development. This is done in some early intervention programs in some states, but it is not done in all. 

  • Determine gestational age in weeks
  • Subtract the gestational age from 40 weeks
  • Subtract the weeks of prematurity

To adjust for prematurity, you can determine the person's gestational age in weeks. You subtract that gestational age from the full term amount of 40 weeks, and then you can see the weeks of prematurity. Let's take a look at this example.

  • Example:
    • Olivia – born at 30 weeks gestation
    • 40 weeks-30 weeks=10 weeks premature
    • Olivia – currently 16 weeks chronologically
    • 16 weeks (chronological age) – 10 weeks premature = 6 weeks adjusted

Baby Olivia is born at 30 weeks gestation, so she is 10 weeks early. Forty weeks minus 30 weeks equals 10 weeks premature. Currently, Olivia is 16 weeks chronologically, meaning she left the womb 16 weeks ago, but we know she is really not supposed to be here yet. She is 16 weeks since she came out of mom's womb, minus the 10 weeks that she should have stayed in there, so she is six weeks of age-adjusted. She came early, but that does not mean that she developed early. She needed 10 extra weeks to develop all of her systems. She not only is not able to develop in that quiet womb-like environment, she is now out in the world trying to do multiple things that she is simply not ready to do.

Associated Diagnoses

There are a number of diagnoses that are associated with prematurity. We are going to talk about some of them, and tie them back to how they impact the child.

Short-Term Complications

  • Hypothermia
  • Respiratory complications
  • Cardiovascular abnormalities
  • Intraventricular hemorrhage (IVH)
  • Necrotizing enterocolitis (NEC)
  • Infection
  • Retinopathy of prematurity (RoP)

Hypothermia. Preterm infants are notorious for having issues with hypothermia. This is because they do not have the stored body fat as a term infant. They have rapid heat loss and cannot generate enough heat to counter what is lost through the surface of their bodies. They have to use energy to stay warm which decreases what they get from their nutrition. This also increases their metabolism, It can be associated with increased mortality, intraventricular hemorrhage, and pulmonary insufficiency.

Respiratory complications. We also see a ton of respiratory complications with preterm infants. Respiratory distress syndrome is a lack of surfactant in the lungs. Surfactant is a liquid that coats the lungs and helps them stay open rather than collapsing. They do have artificial surfactant now which is one of the reasons that there is such an increase in premature deliveries that survive.

Bronchopulmonary dysplasia is also something that we can talk about as a multi-factorial etiology. If an infant has respiratory distress, they may have a prolonged time on the vent, high concentrations of O2, some infection, and many different things that can go on. There are 30 criteria to diagnose bronchopulmonary dysplasia. It essentially alters normal lung development and is synonymous with chronic lung disease.

Then, we have apnea of prematurity, and that is reflecting the immaturity of their respiratory control. Apnea is defined as cessation of breathing for 20 seconds or longer, can be shorter, but if it is accompanied with a slowing of the heart rate, such as bradycardia, that is considered an apneic event. It typically resolves by 36 to 37 post-menstrual age for infants born over 28 weeks gestation. Infants born under 28 weeks gestation can have apnea of prematurity for much longer.

All of these things are very stressful to the infant, and stress, as you will see later in the talk, can have detrimental effects long-term. Here is some of the evidence found with respiratory complications. Lin and colleagues looked at 83 preterm infants with BPD, 89 preterm infants that did not have bronchopulmonary dysplasia, and 98 healthy infants. The followed them for a span of four years and collected data. They found that infants with BPD had higher incidents of adverse neurodevelopmental outcomes when they assessed them at 9 to 12 months than both the regular preemie population and the term population (Lin, et al., 2017). Also in this population, there are very well-documented feeding difficulties (Mizuno, et al., 2007). In this second study, those folks looked at 20 premature infants with varying levels of BPD and noted that severity played a huge role. The infants with the most severe BPD had higher respiratory rates, the biggest O2 desaturations, and lots more documented feeding difficulties. In this last article, Barlow supported the fact that research with infants and respiratory complications is showing that there are greater problems with sucking and maintaining healthy respirations (Barlow, 2009). This is certainly something to think about as you see these children later.

Cardiovascular anomalies. Cardiovascular anomalies are another thing that can happen with prematurity. One thing I want to point out is patent ductus arteriosus or PDA. Before birth, the aorta and the pulmonary artery are connected, and they are connected by a blood vessel called the ductus arteriosus. This is essential for fetal blood circulation. It is supposed to close within minutes or at least within days after birth, and sometimes it does not. When that happens, O2-rich blood from the aorta mixes with that poorer oxygenated blood in the pulmonary artery. It puts a huge strain on the heart, increases blood pressure in the lung arteries, and causes problems. It typically can be managed pretty easily, but there are a few children where it is kept open on purpose depending on if they have other cardiac anomalies. This is something to keep in your mind. They can also have systemic hypotension and blood pressure issues. Lastly, they are two times more likely to present with congenital heart defects than any other population (Laas, et al., 2012). This could be because they are born earlier and are at a higher risk.

As far as research about this, Sterken and colleagues looked at 107 individuals with congenital heart disease and compared them with 77 healthy individuals (Sterken, et al., 2016). They looked for deficits in visual-motor integration and psychosocial functioning. They looked at them at age four and found many more deficits in those two areas with the research group. Another group of researchers looked at heart disease to see if children have a higher incidence of delays across the board. They found that one in five with congenital heart defects had delays in multiple domains and poorer developmental outcomes (Mussatto, et al, 2015). They also found poorer linear growth, feeding problems, longer hospital stays, and so on. Finally, this study supported the idea that kids with cardiovascular diagnoses have increased the risk of neurodevelopmental impairments (Massaro, et al., 2008), but this particular group also found that intelligence appeared to be within normal limits.

Intraventricular hemorrhage. This is the most common neuropathological lesion of the preterm infant. We know it rarely occurs at birth, but it is typically going to occur within the first three days of life. It occurs more frequently in infants born before 32 weeks estimated gestational age. Again, those younger babies are at greater risk. Here is the grading system that we have for intraventricular hemorrhage.

  • Grade I (Mild) Bleeding confined to germinal matrix
  • Grade II (Moderate) IVH occupies 50 percent or less of lateral ventricle volume
  • Grade III (Severe) IVH occupies more than 50 percent of lateral ventricle volume
  • Grade IV (Severe) Hemorrhagic infarction in periventricular white matter ipsilateral to large IVH

You can see Grade I up to Grade IV, which is Mild to Severe. Grade I and II infants will do extremely well. They usually have a resolution of symptoms. For Grade III and IV, this is a different picture. They have more severe IVH with delays and problems.

Klebermass-Schrehof and colleagues said that an IVH diagnosis is associated with significantly lower psychomotor and mental development scores, and there was an increased incidence of CP and visual impairment in this population (Klebermass-Schrehof, et al., 2012). They also noted that an IVH diagnosis, in infants born less than 28 weeks, had poorer outcomes than those who were born later. There are so many reasons for that including the immaturity of the overall system and what they have to go through. Outcomes are of course worse as the grade of IVH increases. Finally, they found that lower grades of IVH, although usually considered to be not nearly as serious, still had higher percentages of negative outcomes as compared to controls without IVH.

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rhonda mattingly

Rhonda Mattingly, EdD, CCC-SLP

Dr. Rhonda Mattingly is an Associate Professor and the Director of Clinical Education in the Department of Otolaryngology, Head and Neck Surgery, and Communication Disorders at the University of Louisville. She has been a practicing speech-language pathologist since 1989 and has spent most of her career working with infants and children with feeding disorders. Dr. Mattingly has provided servics in the early intervention, outpatient, and inpatient settings. She worked at Norton Children's swallowing evaluations on preterm infants, term babies, children, and adolescents. She has provided ongoing treatment and parent/staff education both at Kosair and at other facilities. In addition to other classes, Dr. Mattingly teaches a full semester graduate course in pediatric feeding and swallowing and has taught continuing education courses on the topic in over fifty cities in the U.S and Madrid, Spain. She is currently working with adults and children with swallowing disorders in her practice at the University of Louisville Physicians and is performing pediatric fiberoptic endoscopic swallowing evaluations in the Louisville area.



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