FETAL MEMBRANES IN TWINS and PRETERM BIRTH

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