The first twenty-eight days of a baby's life — the neonatal period — involve the most dramatic physiological transitions the human body undergoes at any point after birth. In the span of minutes to days, the baby must shift from a liquid-filled, placenta-dependent existence to breathing air independently, maintaining its own temperature, and feeding to sustain itself. Understanding what this period involves — what is normal, what to expect, and what is screened for — helps parents navigate the newborn weeks with greater confidence.
Healthbooq supports parents with clear, evidence-based guidance on newborn health and care, including the routine checks and screenings that are offered in the first month.
The Transition at Birth
In the first minutes after birth, several critical transitions must occur. Before birth, the lungs are fluid-filled and not used for gas exchange; oxygenation occurs through the placenta. At birth, the fluid is absorbed or expelled, and the lungs must begin functioning as the organ of gas exchange for the first time. The first breath requires a substantial pressure effort to inflate previously collapsed alveoli.
The circulatory system undergoes major restructuring: the foramen ovale (a hole between the heart's upper chambers) and the ductus arteriosus (a vessel connecting the pulmonary artery to the aorta, bypassing the lungs) must close as blood is rerouted through the lungs. These closures occur over the first hours to days after birth.
The newborn must also begin thermoregulation independently — maintaining body temperature without the constant environment of the womb. Newborns are particularly vulnerable to heat loss because of their high surface area to volume ratio and limited subcutaneous fat; skin-to-skin contact with a caregiver, warm wraps, and a warm environment are important supports in the first hours.
Routine Neonatal Screening
The NHS offers several routine screening procedures in the neonatal period. The Newborn and Infant Physical Examination (NIPE) is offered to all babies within seventy-two hours of birth and again at six to eight weeks. It includes examination of the eyes (for cataracts), heart (for congenital heart conditions), hips (for developmental dysplasia), and testes in boys. The NIPE is carried out by a doctor, midwife, or advanced nurse practitioner.
The newborn blood spot screen (heel prick test) is offered at five days of age. A few drops of blood are taken from the baby's heel and tested for nine conditions: phenylketonuria (PKU), congenital hypothyroidism, cystic fibrosis, sickle cell disease, and five rare but treatable inherited metabolic conditions. The results are typically available within six to eight weeks; no news is good news, though abnormal results are communicated promptly.
Newborn hearing screening is offered before hospital discharge or within a few weeks of birth. It uses an automated test (otoacoustic emissions or automated auditory brainstem response) and takes a few minutes. It screens for significant hearing loss that would benefit from early intervention.
What Is Normal in the First Month
Several features of the newborn period are normal but may concern unfamiliar parents. Physiological weight loss — typically up to 7% of birth weight in the first days — is normal as the baby sheds excess fluid and meconium before milk comes in; birth weight should be regained by ten to fourteen days. Physiological jaundice (yellow skin and eyes) is normal in the first days, reflecting the breakdown of foetal haemoglobin; it typically peaks at day three to five and resolves by ten to fourteen days. Meconium (dark, tarry first stools) transitions to yellow, seedy stools as the baby begins receiving mature breast milk or formula.
Midwifery Contacts in the First Month
Midwifery care is provided from birth until at least day ten (and up to twenty-eight days if needed). Visits typically occur at day one, three to five, and ten, with additional contacts arranged according to need. The health visitor takes over care at around day ten to fourteen.
Key Takeaways
The neonatal period — the first twenty-eight days of life — is a period of rapid physiological adaptation as the newborn transitions from intrauterine to extrauterine life. Multiple body systems undergo dramatic changes: the respiratory system begins functioning, the circulatory system restructures, thermoregulation is established, and feeding begins. UK healthcare provides a framework of newborn checks and contacts across this period to screen for and monitor common neonatal conditions, including the Newborn and Infant Physical Examination (NIPE) within seventy-two hours, heel prick blood spot screening at five days, and regular midwifery visits. Understanding what is normal versus what requires attention in the first month helps parents navigate this period with confidence.
