howMed Know Yourself
n Dizygotic/Fraternal twins (womb- mates)
– 7-11 / 1000 births
– By fertilization of two oocytes shed simultaneously
– Hereditary tendency
– Incidence increases with maternal age
– Sex may be same or opposite
– Resemblance like brothers and sisters
– Placenta may fuse
– Separate amnion and chorionic sac
n Monozygotic twins (identical twins)
– Develop from single fertilized ovum
– 3-4/1000 births
– Genetically identical
– Result from splitting of zygote at an early stage
– Closely resemble in blood groups, fingerprints, sex and external appearance such as eye and hair color
TWIN DEFECTS
n Erythrocyte mosaicism: Anastomosis b/w blood vessels of fused placenta of DZ; RBCs of two different types.
n Twin transfusion syndrome: Shunting of arterial blood from one twin through AV anastomosis into venous circulation of other twin. Donar twin is anemic while the recipient twin is polycythemic.
n Fetus papyraceous: Death and resorption of one fetus
PRETERM BIRTH:
(Delivery before 34 weeks)
Causes:
n Premature rupture of membranes
n Premature onset of labor
n Pregnancy complications requiring premature delivery
n Maternal hypertension
n Maternal Diabetes
n Maternal vaginal infections
