What is the Difference Between Preterm and Small for Gestational Age

The key difference between preterm and small for gestational age is that preterm is a term used to describe a baby when a baby is born too early before completing 37 weeks of pregnancy, while small for gestational age is a term used to describe a baby who is smaller than the usual amount for the number of weeks of pregnancy.

Preterm and small for gestational age infants have increased the rates of prenatal morbidity and mortality. Many a time, stressful events such as economic collapse have been suggested as potential contributors to preterm birth and low birth weight. Therefore, the management of preterm and small for gestational age infants at birth are two extremely important events for the better future of the world.

CONTENTS

1. Overview and Key Difference
2. What is Preterm  
3. What is Small for Gestational Age (SGA)
4. Similarities – Preterm and Small for Gestational Age
5. Preterm vs Small for Gestational Age in Tabular Form
6. Summary – Preterm vs Small for Gestational Age

What is Preterm?

Preterm is a term used to describe a baby when the baby is born too early before completing 37 weeks of pregnancy. Very early preterm birth occurs before 32 weeks, early preterm birth occurs between 32-36 weeks, and later preterm birth occurs between 34-36 weeks. These babies are also known as premature babies, preemies, or premmies. The baby may have mild symptoms due to preterm birth: small size and disproportionately large head, sharper-looking and less rounded features, fine hair covering much of the body, low body temperature, laboured breathing, lack of reflexes for sucking and swallowing that lead to feeding difficulties. Sometimes, preterm babies may have complications such as breathing problems, brain problems, heart problems, temperature control problems, gastrointestinal problems, blood problems, metabolism problems, immune system problems, cerebral palsy, impaired learning, vision and hearing problems, dental problems, behavioral and psychological problems, and chronic health issues.

Preterm birth can be diagnosed through tests like placental alpha microglobulin-1 test, fetal fibronectin test, and ultrasound. Moreover, complications may be diagnosed through specific tests such as breathing and heart rate monitor, fluid input and output test, blood test, echocardiogram, ultrasound scan, and eye exam.

Furthermore, preterm birth babies that have complications can be treated through supportive care, medications (surfactants to respiratory distress syndrome, IV medication to strengthen breathing and heart, antibiotics to infections, diuretics to remove excess fluid, medication to prevent retinopathy in the eye, medicines that help close the heart defect known as patent ductus arteriosus), and surgery.

What is Small for Gestational Age?

Small for gestational age (SGA) is a term used to describe a baby who is smaller than the usual amount for the number of weeks of pregnancy. SGA babies may appear physically and neurologically mature, but they may be proportionately small, or they may be of normal length and size but have lower weight and body mass. SGA babies are preterm (born before 37 weeks), full-term (born between 37 to 41 weeks), or post-term (born after 42 weeks). The causes of this condition can be genetics and fetal growth problems that occur during pregnancy, such as intrauterine growth restriction (IUGR).

SGA babies have symptoms such as decreased oxygen level, low Apgar score (an assessment that helps to identify babies with difficulty adapting after delivery), meconium aspiration, hypoglycemia, difficulty maintaining body temperature, and polycythemia. Babies with SGA can be diagnosed through physical examination, ultrasound, Doppler flow, mother’s weight gain, and gestational assessment. Furthermore, treatments for SCA babies may include temperature-controlled bed or incubators, tube feeding, checking and treating for hypoglycemia (dextrose infusion, glucagon), oxygen therapy for low oxygen level, treating feeding issues by occupational therapists and behaviorists, treating enlarged adenoids or tonsils by ear, nose or throat doctor.

What are the Similarities Between Preterm and Small for Gestational Age?

• Preterm and small for gestational age are two terms used to describe babies that differ from normal birth babies.
• Both preterm and small for gestational age babies may have a preterm birth.
• These babies may have low birth weight.
• Moreover, these babies can have temperature control problems.
• They can be managed through supportive care and other treatments.

What is the Difference Between Preterm and Small for Gestational Age?

Preterm is a term used to describe a baby when that baby is born too early before completing 37 weeks of pregnancy, while small for gestational age is a term used to describe a baby who is smaller than the usual amount for the number of weeks of pregnancy. Thus, this is the key difference between preterm and small for gestational age. Furthermore, a preterm baby can be born between 32 to 36 weeks, while a small for gestational age baby can be born between 37 to 42 weeks.

The below infographic presents the differences between preterm and small for gestational age in tabular form for side by side comparison.

Summary – Preterm vs Small for Gestational Age

Preterm and small for gestational age are two terms used to describe babies differing from normal birth babies. Preterm is a term used to describe a baby when a baby is born too early before completing 37 weeks of pregnancy. Small for gestational age is a term used to describe a baby who is smaller than the usual amount for the number of weeks of pregnancy. So, this is the key difference between preterm and small for gestational age.

Reference:

1. “Preterm Birth.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention.
2. “Small for Gestational Age.” Children’s Hospital of Philadelphia, The Children’s Hospital of Philadelphia.

Image Courtesy:

1. “A premature baby born in Yekatit 12 hospital” By UNICEF Ethiopia (CC BY-NC-ND 2.0) via Flickr
2. “Weight vs gestational Age” By Yehudamalul – Own work (CC BY-SA 3.0) via Commons Wikimedia