Classification of the Newborn, and Gestational Age Assessment

Ultrasound-based methods are the most accurate and widely used techniques for assessing gestational age. They involve measuring specific fetal parameters, such as the:

• Crown-rump length (CRL)
• Biparietal diameter (BPD)
• Femur length (FL)

These measurements are compared to established growth charts to estimate gestational age. The accuracy of ultrasound-based methods is highest when performed during the first trimester and decreases as the pregnancy progresses.

Physical examination involves evaluating certain physical characteristics of the newborn, such as skin texture, lanugo, and plantar creases. The most commonly used physical examination tool for estimating gestational age is the Ballard Score, which assesses 12 physical and neurological characteristics, such as skin texture, ear form, and posture. The score is then compared to a gestational age chart to estimate the newborn's gestational age. The Ballard Score has been shown to be accurate within 1-2 weeks of actual gestational age when performed by experienced healthcare providers.

Ballard Score

The Ballard Score is commonly used when there is uncertainty about the gestational age of a newborn or when ultrasound-based methods are not available.

The Ballard Score consists of 12 different assessments that are scored individually and then added together to provide an overall score. The assessments include:

1. Skin texture: The texture of the newborn's skin is assessed on a scale of sticky, transparent, or peeling.
2. Lanugo: The amount of hair present on the newborn's skin is assessed on a scale of none, scant, or abundant.
3. Plantar surface: The number and depth of creases on the bottom of the newborn's foot are assessed.
4. Breast tissue: The amount of breast tissue present in the newborn is assessed.
5. Eye/ear characteristics: The amount of eye and ear opening, and the presence or absence of ear cartilage, are assessed.
6. Genitalia: The appearance of male or female genitalia is assessed.
7. Posture: The newborn's posture is assessed and scored as either relaxed, some flexion, or well-flexed.
8. Arm recoil: The newborn's arm is extended and then released, and the speed and extent of the arm's return to the body is assessed.
9. Popliteal angle: The angle formed by the newborn's leg and thigh is measured.
10. Scarf sign: The newborn's arm is brought across the body, and the extent to which it can be moved is assessed.
11. Heel to ear extension: The newborn's foot is brought to the ear, and the ease with which this movement is accomplished is assessed.
12. Tone: The newborn's muscle tone is assessed on a scale of flaccid, some flexion, or well-flexed.

Each assessment is given a score of -1, 0, or +1, depending on whether the characteristic is consistent with prematurity, term, or post-term birth. The individual scores are then added together to give an overall score, which corresponds to a gestational age in weeks.

The Ballard Score has been shown to be a reliable and valid method for estimating gestational age, with a mean difference of less than one week between the estimated gestational age and the actual gestational age. However, the accuracy of the score is highly dependent on the experience of the examiner, and inter-rater reliability can vary widely.

Clinical algorithms are another method for assessing gestational age. They use a combination of maternal and newborn factors to estimate gestational age, such as:

• Date of the last menstrual period
• Fundal height
• Birth weight

These algorithms can be useful when ultrasound is not available or when there are concerns about the accuracy of physical examination-based methods.

It is important to note that each of these methods has limitations and potential sources of error. For example, ultrasound-based methods may be less accurate in cases of fetal growth restriction or maternal obesity, and physical examination-based methods may be less accurate when performed by less experienced healthcare providers.

Regardless of the method used, accurate gestational age assessment is critical for guiding appropriate management of newborns. Preterm infants require specialized care to reduce the risk of complications such as respiratory distress syndrome, apnea, and necrotizing enterocolitis. Post-term infants are at increased risk of meconium aspiration syndrome, macrosomia, and birth trauma. Accurate gestational age assessment helps healthcare providers identify infants who may be at risk for these and other complications and provide timely interventions to optimize outcomes.

In conclusion, gestational age assessment is a critical component of newborn care that involves determining the length of a pregnancy. There are several methods for assessing gestational age, including ultrasound-based methods, physical examination, and clinical algorithms. Each method has its limitations, but accurate gestational age assessment is essential for identifying infants who may be at risk for complications and providing appropriate interventions to optimize outcomes.

Gestational age refers to the age of the fetus at the time of delivery.

Gestational age classification is based on the number of completed weeks of gestation. The following are the commonly used classifications of gestational age in a newborn:

1. Preterm: Refers to a newborn who is born before 37 completed weeks of gestation.
2. Late preterm: Refers to a newborn who is born between 34 and 36 completed weeks of gestation.
3. Term: Refers to a newborn who is born between 37 and 41 completed weeks of gestation.
4. Post-term: Refers to a newborn who is born after 42 completed weeks of gestation.

Birth weight refers to the weight of the newborn at the time of delivery.

Birth weight classification is important as it can help identify low birth weight (LBW) and very low birth weight (VLBW) infants who are at increased risk of complications.

The most commonly used classification system is based on birth weight:

1. Normal birth weight: 2,500-4,000 grams
2. LBW: <2,500 grams
3. VLBW: <1,500 grams
4. Extremely low birth weight (ELBW): <1,000 grams
5. High birth weight (HBW): Refers to a newborn who weighs more than 4,000 grams

The Apgar score is a measure of a newborn's physical condition immediately after birth. The five parameters assessed in the Apgar score are:

1. Activity/Muscle tone: The newborn's muscle tone is assessed by evaluating their activity and degree of flexion.
   • A score of 2 is given for active movements and normal flexion.
   • A score of 1 is given for some flexion or resistance to movement.
   • A score of 0 is given for no movement or limpness.
2. Pulse/Heart rate: The newborn's heart rate is assessed using a stethoscope or a pulse oximeter.
   • A score of 2 is given for a heart rate of 100 or more beats per minute.
   • A score of 1 is given for a heart rate of less than 100 beats per minute.
   • A score of 0 is given for no heartbeat.
3. Grimace/Reflex irritability: The newborn's reflex irritability is evaluated by assessing their response to stimulation, such as a gentle pinch or a suction catheter.
   • A score of 2 is given for a prompt response and a vigorous cry.
   • A score of 1 is given for a grimace or weak cry.
   • A score of 0 is given for no response.
4. Appearance/Skin color: The newborn's skin color is assessed by observing their overall appearance and color, including their extremities, trunk, and lips.
   • A score of 2 is given for a normal pink color.
   • A score of 1 is given for a pale or blue color in the extremities.
   • A score of 0 is given for a completely blue or pale appearance.
5. Respiratory effort: The newborn's respiratory effort is evaluated by observing their breathing, chest movement, and cry.
   • A score of 2 is given for strong and regular breathing.
   • A score of 1 is given for slow or irregular breathing.
   • A score of 0 is given for no breathing.

Each parameter is scored from 0-2, and the scores are added together to obtain a total score. A total score of 7-10 indicates a healthy newborn, while a score of 4-6 indicates moderate depression, and a score of <4 indicates severe depression.

Clinical classification is based on the newborn's physical examination and the presence or absence of certain conditions or complications. Examples of clinical classifications include:

1. Well newborn (appropriate for gestational age): Refers to a newborn who is born at term (37 to 42 weeks gestation), has a birth weight appropriate for gestational age, and shows no signs of medical conditions or complications. A well newborn is typically discharged from the hospital within 24 to 48 hours after birth.
2. Small for gestational age (SGA) newborn: Refers to a newborn who has a birth weight below the 10th percentile for their gestational age. SGA newborns may be preterm or born at term but may have growth restrictions due to various factors such as maternal health conditions, placental insufficiency, or genetic factors.
3. Large for gestational age (LGA) newborn: Refers to a newborn who has a birth weight above the 90th percentile for their gestational age. LGA newborns may be born at term or preterm and may have an increased risk of complications such as birth injury, hypoglycemia, and cesarean delivery.