In the first trimester of pregnancy, amniotic fluid is produced from maternal plasma where there is a rapid bi-directional diffusion across the foetal skin. At 10 weeks the volume is about 25ml. By 16th weeks of gestation the foetal kidneys make urine that contributes to the increasing volume of amniotic fluid, along with nasal secretions. At 20 weeks, the level is 400ml and increases to 800ml at 28weeks, after which it reduces to 600ml at term.

Shoulder dystocia occurs when the fetal anterior shoulder impacts against the maternal symphysis following delivery of the vertex. Less commonly, shoulder dystocia results from impaction of the posterior shoulder on the sacral promontory. Risk Factors for Shoulder DystociaMaternalAbnormal pelvic anatomyGestational diabetesPost-dates pregnancyPrevious shoulder dystociaShort statureFetalSuspected macrosomiaLabour relatedAssisted vaginal delivery (forceps or vacuum)Protracted active phase of first-stage labourProtracted second-stage labour

Polycythaemia is a commonly occurring neonatal disorder, which is characterized by a venous haematocrit ≥ 65%. It increases the blood viscosity and causes microcirculatory flow impairment in the end-organs. Causes of polycythaemia are multi-factorial, but the significant risk factors are maternal diabetes, SGA, LGA or post-term birth, infants with chromosomal abnormalities, and delayed clamping of the cord. Jaundice is not a recognized risk factor for polycythaemia.

Spontaneous intestinal perforation (SIP) of the new-born, also referred to as isolated perforation or focal intestinal perforation (FIP) of the new-born, is a single intestinal perforation that is typically found at the terminal ileum. SIP occurs primarily in preterm infants with very low birth weight (VLBW, birth weight <1500 g) and extremely low birth weight (ELBW, birth weight <1000 g), umbilical catheter placement, maternal drug use and twin-to-twin transfusion syndrome. SIP is a separate clinical entity from necrotizing enterocolitis, the most severe gastrointestinal complication of preterm infants.

The perinatal mortality rate is defined as the number of perinatal deaths per 1000 total births. Perinatal death includes the death of a live-born neonate within 7-days of life (early neonatal death) and the death of a fetus ≥ 22 weeks of gestation (stillbirth). Hence, the perinatal mortality rate is calculated by dividing the number of still births+ the number of early neonatal deaths by 1000 births.

The ductus arteriosus is normally patent during fetal life| it is an important structure in fetal development as it contributes to the flow of blood to the rest of the fetal organs and structure. From the 6th week of fetal life onwards, the ductus is responsible for most of the right ventricular outflow, and it contributes to 60% of the total cardiac output throughout fetal life. Only about 5-10% of its outflow passes through the lungs.This patency is promoted by continual production of prostaglandin E2 (PGE2) by the ductus.In the foetus, the oxygen tension is relatively low, because the pulmonary system is non-functional. Coupled with high levels of circulating prostaglandins, this acts to keep the ductus open. The high levels of prostaglandins result from the little amount of pulmonary circulation and the high levels of production in the placenta.At birth, the placenta is removed, eliminating a major source of prostaglandin production, and the lungs expand, activating the organ in which most prostaglandins are metabolized. In addition, with the onset of normal respiration, oxygen tension in the blood markedly increases. Pulmonary vascular resistance decreases with this activity.Normally, functional closure of the ductus arteriosus occurs by about 15 hours of life in healthy infants born at term. This occurs by abrupt contraction of the muscular wall of the ductus arteriosus, which is associated with increases in the partial pressure of oxygen (PO2) coincident with the first breath. A preferential shift of blood flow occurs| the blood moves away from the ductus and directly from the right ventricle into the lungs. Until functional closure is complete and PVR is lower than SVR, some residual left-to-right flow occurs from the aorta through the ductus and into the pulmonary arteriesA balance of factors that cause relaxation and contraction determine the vascular tone of the ductus. Major factors causing relaxation are the high prostaglandin levels, hypoxemia, and nitric oxide production in the ductus. Factors resulting in contraction include decreased prostaglandin levels, increased PO2, increased endothelin-1, norepinephrine, acetylcholine, bradykinin, and decreased PGE receptors. Increased prostaglandin sensitivity, in conjunction with pulmonary immaturity leading to hypoxia, contributes to the increased frequency of patent ductus arteriosus (PDA) in premature neonates.Although functional closure usually occurs in the first few hours of life, true anatomic closure, in which the ductus loses the ability to reopen, may take several weeks. The second stage of closure related to the fibrous proliferation of the intima is complete in 2-3 weeks.

Benign neonatal sleep myoclonus (BNSM) is a disorder commonly mistaken for seizures during the new-born period. It is characterized by myoclonic lightninglike jerks of the extremities that exclusively occur during sleep| it is not correlated with epilepsy.Causes of neonatal seizures:Hypoxic-ischemic encephalopathy: Hypoxic-ischemic encephalopathy disrupts the ATP-dependent sodium-potassium pump and appears to cause excessive depolarization.Intracranial haemorrhage: occurs more frequently in premature than in term infants. Subarachnoid haemorrhage is more common in term infants. This type of haemorrhage occurs frequently and is not clinically significant. Typically, infants with subarachnoid haemorrhage appear remarkably well. Metabolic disturbances include hypoglycaemia, hypocalcaemia, and hypomagnesemia. Less frequent metabolic disorders, such as inborn errors of metabolism, are seen more commonly in infants who are older than 72 hours. Typically, they may be seen after the infant starts feeding.Intracranial infections (which should be ruled out vigorously) that are important causes of neonatal seizures include meningitis, encephalitis (including herpes encephalitis), toxoplasmosis, and cytomegalovirus (CMV) infections. The common bacterial pathogens include Escherichia coli and Streptococcus pneumoniae.Cerebral malformationsBenign neonatal seizures

Vitamin E deficiency in premature infants has been described as being associated with low haemoglobin levels in the 2nd month of life, haemolytic anaemia associated with thrombocytosis. Recently, low vitamin E concentrations were suspected as being associated with sudden death in infancy.

Germinal matrix/intraventricular haemorrhage (GM/IVH) is a complication of premature delivery that can result in life-long medical and developmental consequences.Loss of autoregulation of cerebral blood flow is a pathophysiologic feature of germinal matrix/intraventricular haemorrhage (GM/IVH). Prematurity itself results in derangements in cerebral autoregulation. In some patients, a history of additional events that result in loss of autoregulation can be obtained. Furthermore, events that can result in beat-to-beat variability of cerebral blood flow may be identified in some patients.There may be no symptoms. The most common symptoms seen in premature infants include:- Breathing pauses (apnoea)- Changes in blood pressure and heart rate- Decreased muscle tone- Decreased reflexes- Excessive sleep- Lethargy- Weak suck- Seizures and other abnormal movements

Erb’s palsy is a paralysis of the arm caused by injury to the brachial plexus, specifically the severing of the upper trunk C5–C6 nerves.The infant with an upper plexus palsy (C5-C7) keeps the arm adducted and internally rotated, with the elbow extended, the forearm pronated, the wrist flexed, and the hand in a fist. In the first hours of life, the hand also may appear flaccid, but strength returns over days to months.The right side is injured in 51% of cases. Left side occurs in 45% of patients and bilateral injuries, in 4%.