NORMAL NEONATE

This refers to a baby born at term or as near term as possible after 37 weeks of gestation and has no complications.

Upon birth the infant has to undergo physiological changes in order to adapt to life outside the uterus to have independent existence.

PHYSIOLOGICAL CHANGES AT BIRTH

1. Respiration occurs due to:

· Low oxygen and high carbon- dioxide stimulates respiratory center and respiration begins

· Compression of the chest wall during second stage creates a vaccum and aid respiration

· External stimuli e.g handling the baby, cold extra uterine environment makes the baby gasp and respiration starts

· Baby is encourage to cry initially by flicking the sole of the foot for it allows complete aeration of the lungs

· Presence of surfactant factor aids expansion of the lungs (lecithin:sphingomyelin =2:1 and is an indicator of lung maturity detectable on amniocentesis)

The normal respiration rate at birth is 40-50/ min

Irregular breathing may be due to the following factors:

ü Prematurity (inadequate surfactant factor)

ü Depression of the respiratory centre by drugs e.gpethedine or strong uterine contractions

ü Excessive carbondioxide (hyperpnoea)

ü Lack of oxygen (hypoxia)

2. Circulatory system

· Extrauterine circulation is established and the baby is able to divert deoxygenated blood to the lung for deoxygenation. This accounts for the pink colour of an infant.

· In utero the Hb is high 18-20g/dl and high RBC to transport sufficient oxygen to the foetus. After birth the Hb drops to 14g/dl and some of the RBC are broken down by the liver cells to bilirubin and may lead to physiological jaundice.

· Normal heart rate inutero is 120 -160 beats per minute but upon birth it drops to 100 -120 beats /min

 

3. Temperature regulation

· Temperature in utero is 38*C but the baby’s rectal temperature is 37*C. The temperature drops due to evaporation, conduction, convection and radiation.

· Temperature is not adequately regulated due to low metabolic rate and insufficient heat regulating center in the hypothalamus. They are at risk of overheating as well as chilling.

· They have thin subcutaneous layer which provides poor insulation and heat is lost. They have brown adipose tissue to mobilize heat resources.

4. Digestive system

· Sucking and swallowing reflexes are present and they feed on colostrums and pass meconium (initially green then turns yellow)

· They open bowels 3-4 times a day.

5. Liver

· Stars functioning in utero although negligible. Its function remains depressed for a few days yet it has to handle excess Hb thus there is accumulation of bilirubin leading to physiological jaundice.

6. Urinary system

· A kidney start functioning in utero and the foetus passes urine but has no ability to concentrate urine thus excretes chlorides and phosphates.

· The baby should pass urine within the first 48 hours of birth.

7. Weight

· Average birth weight is 2.5 -3.5 kgs but is affected by factors such as period of gestation, placental function, nutritional status of the mother, size of the parents, type of pregnancy i.e. single or multiple and sex of the baby.

· In the first three days the baby looses 1/10 of its weight (physiological weight loss) due to limited intake, loss of meconium and loss of tissue fluid. The weight is gained within 7-10 days then it gains 250-500g weekly.