Primary Care of the Premature Infant

Background & Objectives

Infants who are discharged from the NICU need ongoing comprehensive clinical care and subspecialty care, which is typically coordinated by PCPs. Through a case discussion, we will discuss special considerations for primary care of premature infants, focusing on

Feeding and nutrition
Respiratory concerns and immunizations
Cardiovascular considerations
Neurodevelopmental concerns
Social issues

The NICU graduate and the late pre-term infant discharged home from the normal newborn nursery share some concerns; this post focuses on infants born premature.

Case

A 90 day-old ex-27 week infant delivered after preterm labor of unclear cause, now corrected to 40 weeks and out of the NICU for 2 days, comes for their first well child check. He is on room air, had no surgeries while admitted, and takes all feeds by mouth. His newborn screen was normal.

What do you want to know before starting your visit? What concerns do you have that might be different from the 3 day-old ex-40 weeker you are seeing right after this baby?

Feeding & Nutrition

This baby was born at <1500g and was transitioned to all PO feeding prior to discharge from the NICU. Mom reports he is doing great and chugging down bottles of 24 kcal/oz formula every 3 hours. She wonders when she can switch him back to “regular” formula since he seems to be doing so well and the NICU told her that his mild constipation is related to the fortified formula.

General Recommendations

Continue fortified feeds until adequate catch-up growth is achieved OR 6 months of chronological age
Usually this means a “transitional” formula, then “regular” infant formula from 6 months to 1 year of chronological age
Recommended growth is a weight gain of 20-25 grams/day
Even when transitioned to WHO growth chart, use corrected gestational age for weight until 24 months, stature until 40 months, and head circumference until 18 months of chronological age
Check weight every week to two weeks until growth trajectory is well established, then space to usual well child checks based on chronological age (or every 1-2 months)

Growth charts galore…

Corrections for gestational age should be made for weight through 24 months of age, for stature through 40 months of age, and for head circumference through 18 months of age. The Fenton preterm infant growth chart is recommended until the infant is 44 to 48 weeks corrected age, at which point the WHO growth curves for term infants can be utilized.

Growth & Neurodevelopment

A 2011 study in Pediatrics found that, in preterm infants, greater weight and BMI gain to term were associated with better neurodevelopmental outcomes. After term, greater weight gain was also associated with better outcomes, but increasing weight out of proportion to length did not confer additional benefit.

Feeding Problems?

If weight is slowing down, remember that GER(D) and oral feeding issues are more common in premature infants!

A 2019 study in the Journal of Pediatric Gastroenterology & Nutrition found that, compared to children born full-term, preterm children demonstrated greater symptoms of feeding problems regardless of their current age, suggesting children born preterm may require more careful monitoring of feeding throughout childhood.

Prematurity, Low Birth Weight, and Obesity

Many studies link low birth weight to obesity in childhood and, increasingly, even cardiovascular disease in later life. There are many proposed mechanisms, and issues with later obesity could be different in preterm babies versus term babies who are low birth weight.

Nutrition & Bone Health

Premature infants are at risk of osteopenia and even rickets (especially ELBW/VLBW babies, who are at highest risk). These infants should have alkaline phosphatase (AP) checked in the NICU around a weight of 2000 g. Those with elevated AP may need further monitoring or to stay on special formula longer.

There is no need for mineral supplementation except vitamin D if on formula; premature and transitional formulas have additional calcium and phosphorous for this purpose.

Breastfed infants should have iron and vitamin D supplementation.

Respiratory Issues

Remember our case: a 90 day-old ex-27 week infant delivered after preterm labor of unclear cause, now corrected to 40 weeks and out of the NICU for 2 days, coming in for their first well child check. He is on room air, had no surgeries while admitted, and takes all feeds by mouth. His newborn screen was normal.

Does it matter if you see this baby in November (versus seeing them in April)?

RSV is a Really Serious Virus

Palivizumab (Synagis) is a monoclonal antibody indicated for the prevention of serious lower respiratory tract disease caused by RSV in certain pediatric patients.

Synagis has been shown to modestly (but significantly) reduce hospitalizations caused by RSV in high-risk patients, but there is no measurable effect on mortality.

Synagis is not a vaccine and does not provide long-lasting immunity. It is administered as a monthly injection (max 5 doses), providing antibodies that last for 28-30 days at a time. Monthly prophylaxis should be discontinued in anyone hospitalized with RSV.

AAP indications for Synagis prophylaxis:

Infants 29 weeks and 0 days gestation or less, and less than 1 year old as of the designated start date for prophylaxis.
Infants less than 32 weeks and 0 days gestation with chronic lung disease (greater than 21% inspired oxygen for at least 28 days after birth) and less than 1 year old at start date.
Infants less than 32 weeks and 0 days gestation with chronic lung disease (greater than 21% oxygen for at least 28 days after birth) and between 1 and 2 years old at start date who require ongoing medical treatment for chronic lung disease (supplemental oxygen, diuretic or steroid therapy).
Infants under 1 year old at start date with hemodynamically significant congenital heart disease (consultation with a cardiologist is recommended).
Infants with pulmonary abnormalities or neuromuscular disease that compromises respiratory secretions.
Infants under 2 years of age with profound immunocompromise.

Wheezing

Infants born more prematurely are at increased risk of wheezing with illnesses, and increased risk of reactive airway disease / asthma. This issues is thought to be related to lung development (though risk is irrespective of BPD diagnosis).

A 2013 article in BMC Pediatrics found that laboratory-confirmed medically-attended RSV infection, prematurity, and neonatal exposure to supplemental oxygen have independent associations with development of recurrent wheezing in the fifth year of life.

BPD

Bronchopulmonary dysplasia is defined by the need for supplemental oxygen at specific concentrations and specific chronologic ages based on gestational age (somewhat complex).

Some patients are discharged on oxygen, and will have multidisciplinary follow-up care. Major PCP points include collaborating with consultants, monitoring respiratory status, and minimizing risk (e.g., secondhand smoke exposure.)

Immunizations

Does being premature change the vaccination schedule? No, it does not!*

Preterm infants should receive all vaccinations by the usual schedule based on their chronological age (not PMA) and started in the NICU
*The one caveat is that Hepatitis B vaccination (for babies of Hep B negative parents) is delayed to time of hospital discharge or 30 days of age for infants < 2kg

Cardiovascular Considerations

A 9-month-old boy is seen for a routine health supervision visit. His parents report no concerns. He is eating well, has appropriate weight gain, and is meeting appropriate developmental milestones. His past medical history is significant for premature birth at 34 weeks’ gestation and a ventricular septal defect, status post repair. He has no residual cardiopulmonary disease. He required only short-term nutritional support and did not require vascular access in the neonatal intensive care unit. His family history is negative for early myocardial infarction, hypertension, or renovascular disease. His physical examination findings are normal. The office does not routinely measure blood pressure in very young children. The physician reviews the discharge summary for recommendations regarding blood pressure monitoring for this child.

Should this child have their BP checked? If so, why?

Infants born at <32 weeks gestation should have BP monitored at al health supervision visits, even before age 3 (which is when the last APP guideline recommends starting BP monitoring for most children.)

Children with congenital heart disease (repaired on unrepaired, regardless of current status) also should have BP checked starting before age 3.

Neurodevelopmental Concerns

Premature infants are at increased risk of

ADHD
ASD
Developmental Delay (all subtypes)
Cognitive and Learning Impairment
Depression
Anxiety
OCD
ODD
Hearing or Vision Loss
Occurring in 35%+ of premature infants!

In determining milestones, remember to use corrected age (not chronological age)!

Social Issues

Being a caregiver of a NICU infant is hard.

“The hospitalization may challenge the normal attachment process and parents’ confidence as caregivers”
“Despite positive effects of rooming-in, [there are] some negative effects, e.g. less sleep and lack of privacy”
“When their baby stays in the NICU, they feel powerless and helpless”
“Have to leave their regular routines and spend many hours in the NICU, where they continue to experience the infants’ fragility and mortality”

Some contextual numbers according to a 2021 study in the Journal of Clinical Medicine:

86.8% of parents were afraid for their baby
During hospital stay, 94.3% of the parents had to modify their routines
69.8% suffered from sleep disturbances
84.9% changed their eating habits
88.5% referred to loss of time for themselves
84.9% neglected their personal appearance and more than half had to give up or reduce their working hours
Time to recover to their family normality ranged from 4 to 11 months

Postpartum depression rate is 28-70% in NICU mothers, compared to 16% for general population!

15% of NICU parents had “moderate-to-severe” PTSD based on a validated civilian questionnaire.

Take-Home Points!

Nutrition is super important! Better nutrition = better neurodevelopmental outcomes
Supplement babies until 6 months OR catch-up growth is achieved
RSV is even more severe among premature babies – find out if your patient needs Synagis!
Premature infants are more likely to wheeze with illnesses (regardless of BPD)
Many premature infants need BP monitoring
Premature infants are at elevated risk of many NDI
Being a NICU parent is hard, and PTSD is common!