The newborn infant

Infants are usually born at term between 37 and 42 weeks of gestation. This time period can be further divided into early term (37 to 38 weeks), full term (39 to 40 weeks), and late term (41 weeks) deliveries. After 42 weeks of gestation, birth is considered postterm. Approximately 10% of births are preterm, occurring prior to 37 completed weeks of pregnancy. Most infants born at term require very little medical attention in order to successfully adapt to extrauterine life. Routine management of a newborn infant immediately after birth consists of removing airway secretions, drying the newborn, and providing him or her with warmth. Health care providers also clamp and cut the umbilical cord. The Apgar score is typically used to gauge the clinical status of newborn infants at one and five minutes after birth using the following parameters: heart rate, respiratory effort, muscle tone, reflex irritability to tactile stimulation, and skin color. Infants who are born at term or late preterm and are breathing and moving satisfactorily should immediately be given to their mother for skin-to-skin contact and initiation of breastfeeding. Infants who are born prematurely, lack muscle tone, or are not breathing or crying may require supplemental oxygen or neonatal resuscitation.

Preventive medicine measures in the delivery room include the administration of ophthalmic antibiotics and vitamin K. Within 24 hours of birth, a detailed assessment of the newborn should take place. This typically includes a history of the pregnancy and a physical exam from head to toe, as well as measurements of length and weight.

General

• Infant: a child under 1 year of age ^[1]
• Newborn: a child under 28 days of age ^[2]
• Perinatal period: the period from the 22^nd week of gestation to the 7^th day after birth ^[3]
• Postpartum period: first 6–8 weeks after birth
• Live birth: postnatal presence of vital signs (e.g., respiration, pulse, umbilical cord pulse) ^[4]

Timing of birth ^[5]

• Term birth: umbrella term for live births between 37 and 42 weeks of gestation
  • Early term infant: live birth between 37 0/7 weeks and 38 6/7 weeks of gestation
  • Full term infant: live birth between 39 0/7 weeks and 40 6/7 weeks of gestation
  • Late term infant: live birth between 41 0/7 weeks and 41 6/7 weeks of gestation
• Preterm infant: live birth between 20 0/7 weeks and 36 6/7 weeks of gestation ^[6]
• Postterm infant: live birth after the 42^nd week of gestation

Evaluation of birth weight

• Appropriate-for-gestational-age infant (AGA): birth weight 10^th–90^th percentile for gestational age
• Small-for-gestational-age infant (SGA): birth weight < 10^th percentile for gestational age ^[7]
• Large-for-gestational-age infant (LGA): birth weight > 90^th percentile for gestational age
• Low birth weight ^[8]
  • Birth weight < 2,500 g regardless of the gestational age
  • Occurs in early term infants and infants with intrauterine growth restriction
  • Associated with increased mortality, particularly due to sudden infant death syndrome
  • Very low birth weight: birthweight between 1,000–1,499 g regardless of the gestational age
  • Extremely low birth weight: birthweight < 1,000 g regardless of the gestational age

Pregnancy loss

• Miscarriage (spontaneous abortion)
  • Absence of vital signs
  • Pregnancy loss before the 20^th week of gestation
  • Fetal weight less than 500 g
• Stillbirth (fetal death)
  • Absence of vital signs
  • Most US states report fetal death if pregnancy loss occurs during or after the 20^th week of gestation
  • Fetal weight more than 500 g

Immediate care of the newborn

• Wipe the newborn's mouth and nose to clear airway secretions, use suction only if necessary.
• Dry and stimulate the newborn.
• Provide warmth.
• Skin-to-skin contact with mother and initiation of breastfeeding
• Clamp and cut the umbilical cord.
• Apgar score assessment at 1 and 5 minutes after birth
• Begin resuscitation if onset of respirations has not yet occurred within 30–60 seconds

Apgar score ^[9]

• Used for standardized clinical assessment of newborns at 1 and 5 minutes after birth
  • Five components: skin color, heart rate, reflex irritability to tactile stimulation, muscle tone, respiratory effort
  • Each component is given 0–2 points, depending on the status of the newborn.
  • The total Apgar score is the sum of all five components.
• Assessing the need for and beginning neonatal resuscitation should be done independently of and before the Apgar score is determined
• Assessment of the Apgar score at 5 minutes: infants with scores < 7 may require further intervention
  • Reassuring: 7–10
  • Moderately abnormal: 4–6
  • Low: 0–3
• In infants with a score below 7, the Apgar assessment is performed at 5–minute intervals for an additional 20 minutes.
• Persistently low Apgar scores are associated with long-term neurologic sequelae.

APGAR: Appearance, Pulse, Grimace, Activity, Respirations

The Apgar score is useful for evaluating the status of a newborn infant, but it should not be used to draw conclusions about individual neonatal morbidity or mortality and it should not be used as a long-term prognostic tool.

Neonatal resuscitation ^[10][11]

• High-risk deliveries: should have a team of health care providers experienced in neonatal resuscitation on hand
  • Maternal factors: very advanced maternal age or very young maternal age, diabetes or hypertension, substance abuse, previous fetal loss
  • Fetal factors: prematurity, postmaturity, congenital anomalies, multiple gestations
  • Complications of pregnancy and delivery: placental anomalies, oligohydramnios/polyhydramnios, transverse/breech delivery, chorioamnionitis, meconium-stained amniotic fluid, abnormal fetal heart rate, delivery with forceps/vacuum/cesarean
• Resuscitation steps
  • Preductal pulse oximetry
  • Positive pressure ventilation (bag-mask ventilation) at a rate of 40–60/minute.
    • Indicated if there is inadequate respiratory effort (e.g., gasping, apnea) or a heart rate < 100 bpm
    • Intubation if pressure ventilation is ineffective or compressions are required
    • Restrictive use of supplementary oxygen guided by pulse oximetry ^[10][12]
      • At birth, ventilation should be provided with room air for infants ≥ 35 weeks gestation.
      • Premature infants < 35 weeks gestation can receive FiO₂ 21– 30% initially, titrated to SpO2.
  • Chest compressions
    • Indicated if heart rate is < 60 bpm despite adequate ventilation for 30 seconds
    • Preferably use the two thumb-encircling hands technique if two health care providers are present.
    • Use the two finger technique if only one health care provider is present.
    • 3 chest compressions followed by 1 inflation
  • IV epinephrine if heart rate < 60 bpm despite adequate ventilation and chest compressions for at least 30–60 seconds
  • If there is no evidence of ROSC within 20 minutes, consider termination of resuscitation. ^[10]

Preventive measures directly after birth

• Ophthalmic antibiotics: to prevent gonococcal conjunctivitis (erythromycin ophthalmic ointment)
• Vitamin K: to prevent vitamin K deficiency bleeding of the newborn (VKDB)

Measurement and a detailed examination of the newborn should take place within the first 24 hours of life. See “Clinical relevance” for examples of pathological findings of a newborn examination.

• Measurements ^[13]
  • Normal range (10^th to 90^thpercentile at 40 weeks gestation)
  • Length: ∼ 50 cm (48– 53 cm)
  • Weight: ∼ 7½ lb (6 lb, 6 oz to 8 lb, 9 oz (2.9–3.9 kg))
    • Boys: 6 lb, 6 oz to 8 lb, 9 oz (2.9–3.9 kg)
    • Girls: 6 lb, 2 oz to 8 lb, 6 oz (2.8–3.8 kg)
  • Head circumference: ∼ 35 cm (33–37 cm)
• Vital signs ^[14]
  • Respiratory rate: 40–60 breaths per minute
  • Heart rate: 120–160 beats per minute
• Bilirubin: see ”Neonatal jaundice”
• pH: ≥ 7.2 (slightly more acidic than adults) ^[15]
• Urine and meconium ^[16]
  • First passage of urine within 24 hours of birth
  • First passage of meconium; (a black-green, tarry substance that forms the newborn's feces) within 48 hours after birth
• Feeding: encourage and provide counseling regarding breastfeeding
• Losing weight after birth ^[17]
  • Loss of up to 7% of birth weight in first five days of life is normal and no specific treatment is required.
  • Newborns normally regain their birth weight by the time they are 10–14 days old.
  • For causes of small-for-gestational-age infants, see “Intrauterine growth restriction.”
• Consequences of intrauterine estrogen exposure
  • Breast bud development is normal in newborns, independent of sex.
  • Newborn girls may have bloody mucoid vaginal discharge.

The physiological respiratory rate and heart rate of newborns are substantially higher than in adults and older pediatric patients.

Healthy newborns normally lose up to 7% of their original birth weight in the first 5 days of life. This weight is then gained back through drinking breast milk and/formula by age 10–14 days. No treatment is necessary.

External signs of maturity

Gestational age is estimated at birth with the Ballard score, which combines neuromuscular assessment with the following physical signs of maturity: ^[18]

• Skin color and texture: rosy
• Body hair: lanugo may be present, thinning, or mostly absent
• Eyes: open
• Ears: well-formed pinna (auricular cartilage) that instantly recoils
• Breast: clearly discernible areola
• Testicles: descended
• Labia: labia minora covered by labia majora
• Plantar creases: cover the entire soles of the feet

Examination for abnormalities

For an overview of potential examination findings, see “Clinically relevant neonatal conditions.”

Face and head ^[18]

• Look for dysmorphic facial features.
• Check head shape (including cranial sutures and fontanelles).
• Perform an eye examination including the Bruckner test for red reflex. ^[19]
• Visualize and palpate the oral palate for cleft palate.
• Check the tongue for ankyloglossia.
• Check for ear abnormalities; low-set ears are often associated with genetic disorders.
• Assess hearing function (see “Newborn hearing screening”).

Intermittent strabismus is a normal finding in children < 4 months of age. ^[20]

Spine and nervous system ^[21]

• Assess the neck.
  • Look for webbing, cysts, pits, masses, and branchial clefts.
  • Ensure there is full range of movement.
• Examine the spine.
• Perform a full neurological examination including assessment of tone.

Thorax ^[18][21]

• Palpate clavicles to exclude neonatal clavicle fracture.
• Look for skeletal deformities (e.g., pectus excavatum) and check for neonatal gynecomastia.
• Look for symmetric movement, and auscultate the chest to detect neonatal pneumothorax.
• Assess for congenital cardiac defects (see also “Newborn screening”).
  • Auscultate for heart sounds.
  • Perform pulse oximetry to exclude cyanotic cardiac defects.
  • Palpate the brachial and femoral pulses to evaluate for coarctation of the aorta. ^[22]

Abdomen ^[21]

• Check that the abdomen is not distended or scaphoid.
• Palpate the abdomen for masses and organomegaly.
• Auscultate for bowel sounds.
• Check the umbilical cord.
  • Ensure there are two arteries and one vein; a single umbilical artery can be associated with other congenital abnormalities.
  • Look for signs of bleeding/infection.

Genitourinary examination ^[21]

• Assess for an imperforate anus.
• Check the inguinal region for hernias.
• In males infants: Rule out cryptorchidism, congenital hydrocele, and hypospadias.
• In female infants: Assess for labial adhesions and abnormalities of the hymen.

Extremities ^[21]

• Check the fingers and toes for supernumerary, absent, or deformed digits.
• Assess the range of motion of all extremities.
• Examine the hips using the Barlow maneuver and Ortolani maneuver to rule out developmental dysplasia of the hip.
• Look for signs of neonatal brachial plexus injury.

Skin ^[21]

• Look for signs of neonatal jaundice.
• Carefully inspect all of the skin for neonatal skin lesions (including birthmarks).

• Before leaving the hospital, newborns should be screened for serious and life-threatening conditions.
• The optimal time for screening is 24–48 hours after birth. ^[23]
• Screening usually involves assessment for:
  • Critical congenital cardiac defects
  • Hyperbilirubinemia
  • Congenital deafness
  • Various genetic disorders, e.g., endocrine, metabolic, and hematological disorders

Which genetic disorders to screen for varies according to national and state law; check local guidelines.

Overview of screening for newborns ^[24][25]

Examples of commonly screened genetic conditions

• Endocrine conditions
  • Congenital hypothyroidism
  • Congenital adrenal hyperplasia
• Metabolic conditions
  • Disorders of fatty acid metabolism
  • Disorders of organic acid metabolism (e.g., isovaleric acidemia, methylmalonic acidemia, propionic acidemia)
  • Disorders of amino acid metabolism; (e.g., phenylketonuria, homocystinuria, maple syrup urine disease, citrullinemia type I)
• Hemoglobinopathies (e.g., sickle cell disease, beta thalassemia)
• Other conditions
  • Cystic fibrosis
  • Classical galactosemia
  • Severe combined immunodeficiencies (SCID)
  • Glycogen storage disease type II (Pompe disease)
  • Mucopolysaccharidosis type I
  • X-linked adrenoleukodystrophy
  • Spinal muscular atrophy
  • Biotinidase deficiency
    • Etiology: metabolic disorder that leads to biotin deficiency
    • Clinical features: dermatitis, CNS damage
    • Treatment: biotin substitution

Skin

• Neonatal skin lesions

Head

• Head molding
• Caput succedaneum
• Cephalohematoma
• Subgaleal hemorrhage
• Bulging fontanelles as a sign of increased intracranial pressure
• Facial nerve palsy due to birth trauma

Eyes

• Retinopathy of prematurity
• Newborn conjunctivitis
• Leukocoria (may indicate retinoblastoma)

Ear, nose, and mouth

• Cleft lip or cleft palate
• Choanal atresia

Neck and clavicles

• Birth-related clavicle fracture
• Infant torticollis

Circulatory system

• Neonatal respiratory distress syndrome
• Cyanotic and acyanotic congenital heart defects

Gastrointestinal tract

• Hirschsprung disease
• Necrotizing enterocolitis
• Vitamin K deficiency bleeding of the newborn

Urogenital system

• Congenital adrenal hyperplasia
• Neonatal acute kidney injury

Trunk, spine, and extremities

• Infantile hypotonia
• Neural tube defects
• Foot deformities (e.g., club foot, metatarsus adductus)
• Hip dysplasia
• Brachial plexus injuries

Endocrine organs

• Neonatal hypocalcemia
• Congenital hypothyroidism
• Congenital hyperinsulinism
• Neonatal diabetes
• Congenital hypopituitarism

Hematological system

• Physiologic anemia of infancy
• Neonatal polycythemia

Erythema toxicum neonatorum

• Definition: : a benign, self-limiting rash that appears within the first week of life
• Etiology: unknown (probable contributing factors: immature sebaceous glands and/or hair follicles)
• Clinical features
  • Small, red macules and papules that progress to pustules with surrounding erythema
  • Located on trunk and proximal extremities
  • Spares the palms of hands and soles of feet
• Diagnostics
  • Based on clinical appearance of rash
  • Biopsy or smear of pustula (rarely necessary): ↑ eosinophils
• Treatment: observation only
• Prognosis: : typically resolves without complications within 7–14 days

Congenital dermal melanocytosis (Mongolian spot)

• Definition: benign blue-gray pigmented skin lesion of newborns
• Neonatal prevalence ^[28]
  • Asian and Native American: 85–100%
  • African American: > 60%
  • Hispanic: 46–70%
  • White: < 10%
• Pathophysiology: melanocytes migrating from the neural crest to the epidermis during development become entrapped in the dermis
• Clinical features
  • Blue-gray pigmented macule (may also be green or brown)
  • Location: most common on the back, also seen on the buttocks, flanks, and shoulders
  • Diameter: typically < 5 cm, may be > 10 cm
• Diagnostics
  • Based on clinical appearance
  • It is important to document the diagnosis of Mongolian spots, as they may resemble bruises and lead to false suspicions of child abuse.
• Prognosis: : usually resolves spontaneously during childhood (typically by the age of 10 years) ^[29]

Congenital melanocytic nevus

• Definition: a congenital skin lesion caused by the proliferation of melanocytes
• Epidemiology: 1/20,000 births ^[30]
• Clinical features ; ^[30]
  • Light to darkly pigmented, well-circumscribed macule or patch
  • Often with increased hair growth
  • Vary in size: < 1.5 cm to > 20 cm
  • A nevus larger than 20 cm in size is referred to as a giant congenital melanocytic nevus
• Treatment: surgical excision or laser ablation (depending on type and size of lesion)
• Prognosis: large nevi are at risk of degeneration → frequent follow-up

Infantile hemangioma (strawberry hemangioma)

• Definition: benign capillary vascular tumor of infancy
• Epidemiology
  • Occurs in 3–10% of infants ^[31]
  • More commonly affects girls
• Pathophysiology
  • Abnormal development of vascular endothelial cells
  • Rapid proliferation followed by subsequent spontaneous slow involution (occurring at the age of 5–8 years) ^[32]
• Clinical features
  • Manifests during the first few days to months of life
  • Progressive presentation; : blanching of skin → fine telangiectasias → red painless papule or macule (strawberry appearance)
  • Most commonly on head and neck
  • Usually solitary lesions
• Diagnostics
  • Based on clinical findings
  • The differential diagnosis of cherry angioma is found mostly in adults.
• Treatment
  • Active nonintervention (monitoring, parental education)
  • Systemic therapy with propranolol in complicated cases
    • Rapidly growing cutaneous hemangiomas
    • Periorbital hemangioma: vascular anomaly in the periorbital region, most commonly the upper eyelid
    • Hemangiomas in the airways, gastrointestinal tract, or liver
    • Hemangiomas with high risk of complications
  • If unresponsive to medication
    • Cryotherapy
    • Laser therapy
    • Resection if necessary
• Complications
  • Ulceration
  • Disfigurement
• Prognosis
  • Usually good prognosis
  • Spontaneous resolution is common
  • Visual impairment if periorbital hemangioma is left untreated

Others

• Milia neonatorum
  • Definition: tiny epidermal papules caused by the buildup of keratin and sebaceous secretions
  • Clinical features: pinhead-sized lesions located on the face/trunk
  • Treatment: not necessary
  • Prognosis: benign skin lesion, spontaneous resolution without scarring
• Capillary malformations (naevus flammeus, port-wine stain, firemark)
  • Definition: congenital, benign vascular malformations of the small vessels in the dermis
  • Epidemiology: may occur in association with a neurocutaneous disorder such as Sturge-Weber syndrome
  • Clinical features: typically unilateral, blanchable, pink-red patches that grow and become thicker and darker with age
  • Treatment: cosmetic laser treatment if desired (not necessary)
  • Prognosis: benign skin lesion
• Transient neonatal pustular melanosis (TNPM)
  • Definition: a benign, transient, idiopathic neonatal skin condition
  • Epidemiology ^[33]
    • Incidence: ∼ 2%
    • Most commonly occurs in African American infants (5 %)
  • Clinical features
    • Solitary or clustered pustules and vesicles on a nonerythematous base
    • Hyperpigmented, erythematous macules and collarettes of fine scale
    • Most commonly affects the forehead, anterior neck, and lower back
  • Treatment: reassurance
  • Prognosis: benign, self-limiting skin lesion
• Nevus anemicus
  • Definition: a pale patch of skin that does not create erythema in response to trauma, heat, or cold
  • Etiology: caused by a vascular anomaly (increased sensitivity of cutaneous blood vessels to naturally occurring catecholamines)
  • Treatment: not required
• LEOPARD Syndrome (Noonan syndrome with multiple lentigines)
  • Lentigines: lenticular hyperpigmentation (dark macules)
  • Electrocardiographic conduction abnormalities
  • Ocular hypertelorism
  • Pulmonary stenosis
  • Abnormalities of genitalia
  • Retardation of growth
  • Deafness
  • See “Noonan syndrome” in “Rare inherited syndromes.”
• Neonatal acne
• Blueberry muffin syndrome
  • A descriptive term for neonates born with multiple bluish, purple marks in the skin, which can be due to extramedullary erythropoiesis, purpura, or metastases.
  • The differential includes various cancers (e.g., rhabdomyoscarcoma), blood disorders (e.g., hemolytic disease of the new born), and congenital viral infections (e.g., rubella)

Some congenital infections may manifest with rashes or other skin conditions and should be differentiated from benign skin lesions in the newborn.

• Definition: a physiologic decrease in RBC production that typically appears at 8–12 weeks of age in term infants and 4–8 weeks of age in preterm infants
• Pathophysiology ^[34]
  • Increase in oxygenation → ↑ in tissue oxygen levels → ↓ production of erythropoietin
  • Shorter lifespan of erythrocytes (60–90 days in term infants and 35–50 days in preterm infants)
• Clinical features
  • Term infants: typically asymptomatic
  • Preterm infants: rapid decline of HB that may be more severe, often manifesting with pallor, apnea, lethargy, and/or poor feeding
• Diagnostics: screening for anemia should be performed at 12 months of age via measurement of Hb levels. ^[35]
• Differential diagnoses
  • Blood loss (e.g., due to frequent sampling)
  • Increased RBC destruction (e.g., due to immune hemolytic anemia, hereditary spherocytosis)
  • Decreased RBC production (e.g., due to congenital hypoplastic anemia)
• Treatment ^[34]
  • Term infants: physiologic anemia is typically well tolerated; no treatment is necessary.
  • Preterm infants: Treatment is indicated if Hb levels are < 7 g/dL.
    • Optimization of feeding with iron supplementation
    • Blood transfusion may be considered in symptomatic patients with reticulocytopenia.

• Definition: venous hematocrit (HCT) greatly exceeding normal values for gestational and postnatal age
• Epidemiology: 1–5% of newborns ^[36]
• Risk factors
  • SGA
  • LGA
  • Infants of diabetic mothers
  • Delayed umbilical cord clamping
  • Intrauterine hypoxia (e.g., maternal tobacco use)
  • Twin-to-twin transfusion syndrome (recipient)
  • Chromosomal abnormalities
• Pathophysiology
  • Maternal hyperglycemia → chronic fetal hyperglycemia → ↑ metabolic effects and oxygen demand → fetal hypoxemia → ↑ erythropoietin concentrations
  • Delayed umbilical cord clamping → erythrocyte transfusion → ↑ circulating red blood mass (HCT)
  • Placental insufficiency or chronic intrauterine hypoxia → increased intrauterine erythropoiesis → ↑ circulating red blood mass (HCT)
• Clinical features
  • Respiratory distress, cyanosis, apnea
  • Poor feeding, vomiting
  • Hypoglycemia
  • Plethora
  • Lethargy and irritability
  • Tremors or seizures
• Diagnostics
  • Venous HCT > 65%
  • Hemoglobin > 22 g/dL
• Treatment (if symptomatic)
  • Monitoring
  • IV hydration
  • Partial exchange transfusion: a procedure in which part of the blood is replaced with an isotonic fluid to lower the hematocrit
    • Indicated in asymptomatic patients with high hematocrit (> 75%) or symptomatic patients with hematocrit > 65% ^[37]
    • Increased risk of NEC ^[38]
• Complications
  • Hypoglycemia
  • Hyperbilirubinemia
  • Hyperviscosity syndrome
  • Low iron stores
  • NEC

• Definition: low blood glucose in a newborn
• Subtypes
  • Transitional neonatal hypoglycemia: a normal physiological drop in a newborn's plasma glucose levels within the first 2 hours of life that typically resolves within 72 hours of birth
  • Persistent neonatal hypoglycemia: low plasma glucose levels (< 50 mg/dL) in a newborn that persist beyond the first 48 hours of life
    Risk factors ^[39][40]
    • Persistent hyperinsulinemic hypoglycemia (e.g., due to gestational diabetes)
    • Prematurity
    • Intrauterine growth restriction
    • Small for gestational age
    • Large for gestational age
    • Persistent hypoglycemia
      • Perinatal stress (e.g., sepsis, maternal preeclampsia or eclampsia)
      • Congenital syndromes (e.g., Beckwith-Wiedemann syndrome)
      • Congenital hyperinsulinism or hypopituitarism
      • Postterm infants
• Pathophysiology
  • Inadequate glycogen stores and/or impaired glucose production
  • Increased glucose utilization
    • Maternal hyperglycemia → fetal hyperglycemia → beta cells hypertrophy and hyperfunctioning → fetal and neonatal hyperinsulinemia → delivery → ↓ maternal glucose supply → transient hypoglycemia
    • Insufficient glycogen stores and hyperinsulinemia → impaired hepatic glycogen mobilization → transient hypoglycemia
• Clinical features
  • Usually asymptomatic
  • Autonomic symptoms (e.g., tachycardia, sweating, tremors)
  • Neurological symptoms (e.g., hypotonia, irritability, poor feeding, lethargy, seizures)
• Diagnostics: Glucose levels should be obtained for symptomatic infants and/or those with known risk factors. ^[40][41][42]
  • Asymptomatic infants: blood sugar levels < 45 mg/dL within 24–48 hours or < 50mg/dL thereafter
  • Symptomatic infants: blood sugar levels < 40 mg/dL within the first 48 hours or < 50mg/dL thereafter
• Treatment ^[39]
  • Close glucose level monitoring for the first 24–48 hours
  • Oral or IV glucose supplementation, if necessary.
• Prognosis ^[40]
  • Transient hypoglycemia: glucose levels typically increase and stabilize between 45 and 80 mg/dL by the first 72 hours
  • Persistent hypoglycemia: prognosis depends on the underlying etiology.

• Definition: a fetus that is > 4000 g (8 lbs 13 oz), regardless of gestational age
• Etiology ^[43]
  • Diabetes mellitus in pregnancy
  • Previous macrosomic fetus
  • Multiparity
  • Maternal obesity
  • Excessive gestational weight gain
  • Maternal birth weight (> 4,000 g or 8 lbs 13 oz)
  • Postterm pregnancy
  • Genetic and congenital disorders (e.g., Beckwith-Wiedemann syndrome)
• Pathophysiology ^[43]
  • Maternal hyperglycemia → fetal hyperglycemia → stimulation of fetal pancreas → fetal hyperinsulinemia → ↑ insulin, insulin-like growth factors, growth hormone, and other growth factors → ↑ fetal growth, fat deposition, hepatic glucose uptake, and glycogen synthesis → ↑ delivery to insulin-sensitive tissues (e.g., heart, liver, skeletal muscle)
  • ↑ Maternal lipid levels → ↑ supply of fatty acids to the fetus and fetal hyperinsulinemia → incorporation of fatty acids into fetal adipocytes → ↑ fetal adiposity
• Diagnostics: > 4000 g (8 lbs 13 oz), as estimated by ultrasound measurements (e.g., fetal abdominal circumference)
• Complications
  • Fetal
    • Birth injuries (e.g., shoulder dystocia, brachial plexus injury)
    • Acute respiratory distress, transient tachypnea of the newborn
    • Neonatal hyperbilirubinemia
    • Neonatal polycythemia
    • Neonatal hypoglycemia
    • Metabolic acidosis
    • Stillbirth
    • Long-term complications (e.g., insulin resistance, obesity)
  • Maternal
    • Genital tract lacerations
    • Postpartum hemorrhage
    • Uterine rupture
    • Protracted or arrested labor
• Prevention
  • Individuals with diabetes mellitus in pregnancy should achieve adequate glycemic control.
  • All pregnant individuals should avoid excessive weight gain.