3. DEFINITION
A reduction in red cell volume or hemoglobin
concentration below range of values occurring in
healthy newborn with respect to gestational age.
Is there a cut off? Depends on
Post natal age of neonate
Birth weight
Site of sampling (capillary vs. venous)
Term infant at birth, venous sample 14-20g/dl..
Average 17g/dl
Few clinical disturbances occur till Hb 7-8g/dl ??
2/8/2024
4. Normal Hb Levels
What shall we say then,
cord blood levels <13g/dl in term & premature (<36 wks
gestation) should be interpreted as abnormal
In very premature infants < 26wks gestation, values as
low as 12g/dl may be acceptable
If anemia is confirmed, a prompt and careful search for
the cause should be initiated.
2/8/2024
5. Development of
erythropoiesis
Hematopoiesis in embryo and fetus
Hepatic -chief site 3-6mo in utero
Myeloid – takes over 6 mo
First cells produced in embryo are red cells
2/8/2024
6. Erthropoiesis after birth
In the bone marrow
Rate of Hb synthesis and red cell production
dramatically decreases(nadir 2nd wk, then increase to
max at 3/12 2ml packed cells/day
Sudden decrease is initiated by equal sudden increase in
tissue [oxygen ]at birth
At birth 55-95% is HbF , thereafter HbA more
2/8/2024
8. Control of Erythropoiesis
Erythropoiesis is controlled by a negative feedback loop
involving erythropoietin (EPO) .
↓ RBC mass - ↑ EPO which drives erythropoiesis to ↑RBC
mass which in turn reduces EPO production
2/8/2024
10. Blood loss
Prenatal or at birth
Laboratory sampling
Occult hemorrhage before birth-fetal to maternal
hemorrhage, twin to twin transfusion.
Obstetric accidents-umbilical cord rupture in
precipitous labour, unusually short, entangled around
neck, traction with forceps, arterial aneurysm. APH
Inadvertent incision during CS
2/8/2024
16. Physiologic anaemia of
prematurity
The Hb of normal term infants usually decreases over
first few weeks of life (physiologic anaemia of
infancy).nadir 11-12g/dl, 8-12wks.
Physiologic process , asymptomatic, requires no
treatment.
Preterms have an exaggerated decrease (physiologic
anaemia of preterms). nadir 7-8g/dl, 4-8wks,more
immature, lower nadir.
2/8/2024
17. 2/8/2024
The physiological phenomenon is due to:-
Increase in tissue oxygenation at birth (placenta to lungs)
Rapid body growth
Shortened rbc lifespan 80d vs 120d
Low blood erythropoietin due inadequate production and bunted
EPO response to decreasing Hb.
Decrease in hematopoietic activity.
Editor's Notes
Preterms 1-2g/dl lower
Site of sampling will see later.
HbA production starts in utero, after 34-36 week the % of HbA increases while HbF reduces.
At birth the proportions of HbF to HbA are 53-95%
What are the advantages of HbF over A : it has higher affinity for oxygen, thus gives the developing fetus better access to maternal oxygen.
HbF decreases after birth by approx 3%/week to <2 to 3 % by 6 mo..
Hereditary persistence of fetal hb, thal B..can be 100% HbF, SCD max 20%
Item 6 switch delayed in infants of DM mothers, Brochopulm dysplasia, those with inability to metabolise propionic acid
The expected correlation between EPO and oxygen delivery (eg Hb, venous oxyen tension) can be detected in premature infants providing evidence that the feedback loop exists
Velamentous placenta-umbilical vessels attach to the fetal membranes between chorion and amnion. No protection with whartons jelly, liable to rupture
Sub aponeurotic bogginess from front to occiput, for each increase in HC beyond expected 35mls of blood.
Several cases of homozygous SCD have been seen clinically in neonates, a B chain, HBS usually <20%.
A thal causing anaemia in newborn invariably is homozygous a thall(microcytosis), HbBarts gamma tetramer.
Mention En passant..
Diamond blackfan syndrome-microcephaly,eye anomalies,web neck,thumb deformities;bifid or triphallangeal thumb, cleft palate
