LECTURE FOUR
Prematurity :Live infants delivered before 37 wks from the last day of the last menstrual period .
Low birth weight ( weight 2.5 kg or less ) due to prematurity or to poor intrauterine growth or both .Prematurity and IUGR are associated with increased neonatal morbidity and mortality
Very low birth weight infants weigh less than 1.5 kg .and predominantly premature .
Causes of prematurity
Fetal like ( multiple gestation , fetal distress , ).
Placental ( placenta previa , placental dysfunction ).
Uterine ( bicornuate uterus ) .
Maternal ( heart diseases , D .M . ,renal disease , maternal infection ).
Others like premature rupture of membrane ,trauma , polyhydramios .
A premature infant may show these signs soon after birth :
Trouble breathing .
Low weight .
Low body fat .
Inability to maintain a constant body temperature .
Less activity than normal .
Movement and coordination problems .
Complication of prematurity :
Brain hemorrhage .
Pulmonary hemorrhage .
Hypoglycemia .
Infection .
Anemia .
Patent ductus arteriosus .
Respiratory distress syndrome .
Long term outlook for premature infants include :
Hearing and speech problems .
Vision loss or blindness .
Learning disability .
Physical disability .
Delayed growth and poor coordination .
that interfere with the circulation and efficiency of the placenta , with the development or growth of the fetus or with the general health and nutrition of the mother .
Intrauterine growth restriction and small for gestational age :
IUGR represent a deviation from expected growth pattern . the decreased fetal growth associated with IUGR is adaptation to unfavorable intrauterine conditions that result in permanent alteration in metabolism , growth and development .SGA describes an infant who birth weight is statistically less than 10th percentile or two standard deviation below the mean birth weight for gestational age .
Causes of IUGR and SGA :
Maternal causes ( genetic short stature, infections , young age , smoking , poor nutrition black race , chronic diseases like diabetes)
Fetal ( congenital infection , defect in metabolism , multiple gestation , chromosomal abnormalities ) .
Maternal medication ( antimetabollites , lead, mercury , narcotics steroid , warfarin ).
Placental and uterine ( abruption placentae , abnormal implantation)
At birth infants who are mildly to moderately SGA appear smaller than normal with decreased subcutaneous fat .More severely affected may present with a wasted appearance with asymmetrical findings including larger head for size of the body (central nervous system sparing ) widened anterior fontanelles , small abdomen, thin arms and legs, decreased subcutaneous fat, dry skin and meconium stained umbilical cord .
Physical examination should detail the presence of dysmorphic features like abnormal extremities and hepatosplenomegaly . jaundice , skin rash and cataract that may suggest the presence of congenital infection or metabolic defect .
Infants with severe IUGR or SGA may have problems at birth include respiratory acidosis ,metabolic acidosis , asphyxia , hypotension , hypoglycemia , polycythemia , meconium aspiration syndrome .
Management of IUGR and SGA infants is usually symptomatic and supportive . the diagnosis evaluation at birth should be directed the cause if possible . the mortality rate are 5-20 times those of infants who are appropriate for gestational age , postnatal growth and development depend on part on the etiology , the postnatal nutritional intake and the social environment .infants who have IUGR and SGA secondary to congenital infection , chromosomal abnormalities or constitutional syndromes remain small throughout life . infants who have growth inhibited late in gestation because of uterine constraints , placental insufficiency , or poor nutrition have cutch up growth and approach their inherited growth and development potential under optimal environmental conditions .
Post –term infants :
Post term infants are those born after 42 completed weeks of gestation regardless the birth weight .Clinical features may involve skin desquamation , long nail, abundant hair ,pale skin alert face , and loose skin, meconium stained nails and umbilical cord .
Complication include ( perinatal depression . meconium aspiration . persistent pulmonary hypertension , hypoglycemia , hypocalcemia , and polycythemia .
Large –for- gestational – age infants:
Infants with birth weight >the 90th percentile for gestational age are called large for gestational age . neonatal mortality rate decrease with increasing birth weight until approximately 4kg after which they increased . maternal diabetes , obesity and large parental size are predisposing factors .infant have a higher incidence of birth trauma like ( brachial plexus injuries, fractured clavicle cephalhematoma )
Increased risk of hypoglycemia and polycythemia , congenital anomalies ,
Multiple gestation :
Multiple gestation always should be seen as a high risk event owing to its increased association with intra uterine accidents , growth abnormalities , prematurity and problems at the time of delivery like abnormal position and asphyxia .1-Incidence . approximately 1-1.3% of all live birth are the result of twin gestation . the true incidence of twin gestation is probably is slightly higher . the monozygotic twining rate is 3.5-4 in 1000 live births or 35-40 %of all twin who are born .
Etiology :
a-monozygotic twin : maybe viewed as a teratogenic event because it occurs more frequently with increasing maternal age .is associated with more congenital malformation and can be caused by teratogen . a problem of a symmetry in the developing embryo may result in conjoined twins .the incidence of monozygotic twins is unaffected by racial and familial factors .
b-dizygotic twinning :is caused by double ovulation , which may be related to elevated gonadotropin .twin not of the same sex are dizygotic . in twin of the same sex , zygosity should be determined and recorded at birth through careful examination of placenta .
c. incidence increase due to treatment of infertility with overian stimulant and in vitro fertilization .
Prenatal problems :
Death : may be occur because of cord accidents and twin to twin transfusion , which may lead to the death of one fetus , with thromboplastin release and subsequent DIC in the second twin .
Growth disturbances are the rule :
(1)- IUGR there is a decrease potential for growth in twin fetus compared to a single fetus ., probably owing to the limitation of placental area for nutrient transfer .
(2)- twin to twin transfusion , resulting in a large polycythemic twin and a small anemic twin .
c- the incidence of congenital malformation is doubled .
Increased spontaneous apportion .
Preterm delivery is the most common complication of multiple gestation it occurs in up to 50% of twin pregnancies , the incidence is even higher in triplet and quadruplet pregnancy .
Maternal complications include
Pregnancy induced hypertension .
Polyhydramnios .
Hyperemesis and nausea .
Anemia .
Postnatal problems include :
Prematurity and its complications.
Growth retardation.
Perinatal asphyxia .especially of the second twin because the placenta may be separated after birth of the first twin . and in instances of malpresentation or vasa previa may result in long term morbidity and mortality .
Management is aimed at :
Identifying multiple gestation as early as possible .
Managing other medical problems .
Controlling preterm labor .
Identifying ideal route of delivery .
Avoiding asphyxia in the second twin
Maternal diseases affecting the newborn
Idiopathic thrombocytopenia ITP : ITP is immune process in which antibodies are directed against platelets that cross the placenta and cause thrombocytopenia in the fetus and newborn , that increase the risk of intracranial hemorrhage .close maternal and fetal management is vital . infants with hemorrhage may need platelets transfusion or intravenous immunoglobulin .the condition usually resolve within 4-6 wks .
Systemic lupus erythematosus SLE : immune abnormalities in SLE can lead to the production of antibodies that can cross the placenta and injure fetal tissues and the most serious problems in fetus is damage to the cardiac conducting system which result in congenital heart block . neonatal lupus may occur and is characterized by skin lesion thrombocyropenia , autoimmune hemolysis and hepatic involvement . the mortality rate is about 2o% and most surviving infants require pacing .
Neonatal hyperthyroidism : is due to the transplacental passage of thyroid –stimulating antibodies , hyperthyroidism can appear rapidly within the 12 to 48 hrs . symptoms may include IUGR prematurity , goiter exophthalmos , stare , craniosynostosis . flushing, congestive heart failure tachycardia ,arrhythmia , hypertension , hypoglycemia , thrombocytopenia and hepatosplenomegaly .treatment include propylthiouracil , iodine drops and propranolol .the condition usually resolve in 2-4 months .
Antiphospholipid syndrome: is associated with throbophilia and recurrent pregnancy loss . antiphspholipid antibodies are found in 2-5% of the general healthy population . obstetric complications arise from the prothrombotic effects of the antiphospholipid antibodies on the placental function . vasculopathy ,infarction, and thrombosis have been identified in the mothers with antiphospholipid syndrome that manifested by fetal growth impairment , placental insufficiency , maternal preeclampsia and premature birth .
Diabetes mellitus :