normal neonatal changes pathogenesis and clinical findings

Normal Neonatal Changes: Physiology and Clinical Findings The neonatal period is between infants’ time of birth and 4 weeks gestational age.
This slide focuses only on changes that are part of the normal growth and development of neonates born at full term (38-42 weeks).
Authors: Erin Auld, Dasha Mori Reviewers: Kayla Feragen Mao Ding Danielle Nelson* *MD at time of publication
Birth weight: Loss of birth weight up to 10%; should be re-gained within 10-14 days (30 g/day)
Stool: transitions from meconium (first stool of neonate that is black, tarry and sticky) to normal (green/brown or yellow mustard) within 2-3 days
Meconium passage: within 24 hours of birth
• Height: 2.5 cm/month
• Head Circumference: Average 1 cm/month in the first year with greatest growth in the first month • Weight: 20-30 g/day for the first 3 months
Urination: within the first 24 hours
Mother receives intravenous fluids during delivery
Colostrum (first milk secretion that contains antibodies) produced in first 2-3 days of lactation post-partum (Lactogenesis I)
GI tract maturation
Adequate dietary intake
Maturation of urinary tract
Adequate fluid intake
↑ maternal blood volume
Fluid moves between fetus and mother through placenta
Fetus’s fluid volume ↑
Infant’s urine output ↑ in first 24 hours post-partum
Low breast milk intake in first 2-3 days
↓ progesterone, ↑ prolactin in mother at birth
Infant ingests colostrum
Mostly water loss, some fat loss
↑ Breast Milk Production (Lactogenesis II)
Stomach stretches
↑ in gastrointestinal tract motility (gastrocolic reflex)
Ingestion of milk post-partum further stimulates GI maturation
110-120 kilocalories/kg/day
Gastrointestinal tract formation begins when the fetus is 4 weeks old. Maturation continues into infancy.
Normal gestational age (38-42 weeks)
Fetus ingests amniotic fluid in utero
Stimulates structural changes, enzymatic activity, and metabolic activity of GI tract
Mature detrusor sphincter complex, appropriate bladder capacity, proper renal perfusion, and regular arousal of the neonate
Breast milk: Feeding when infant demands it, approximately every 2-3 hours Formula: Feeding when infant demands it, approximately every 4 hours
Sign/Symptom/Lab Finding
Published Oct 24, 2015, updated Sept 28, 2023 on