Multiple Pregnancy

Multiple Pregnancy

·        Causes of large uterus for dates (in order of occurrence):

o   Incorrect date for LMP

o   Distended bladder

o   Multiple fetuses

o   Polyhydramnios

o   Adnexal mass

o   Large for gestational age fetus

o   Fetal macrosomia (in diabetes)

o   Hydatiform mole

·        Dizygotic twins:

o   Baseline risk: 1in 80 pregnancies.  1 in 40 if primary relative a dizygotic twin

o  Siblings that happen to share the uterus as the same time: separate placentas, amnions, and chorions

o  2/3 of twins

o  7 – 11 per 1000 births

o  Risk factors: > 35 years, high parity, ethnicity and assisted conception

·        Monozygotic twins:

o  Family history has minimal risk for monozygotic

o  Splitting at two cell stage (< 5 days) gives separate placenta, amnion and chorion 

o  Splitting at inner cell mass (5 – 10 days) gives common placenta and chorionic sac, but separate amnions (most common – 70%) 

o  Splitting of inner cell mass at later, bilaminar disc stage gives common placenta, amnion and chorion

·        Problems: 

o  Cord entanglement: highest risk < 30 wks ® occlusion and fetal death

o  Conjoined twins (1% of monozygotes): incomplete splitting of primitive node

o  Twin reversed arterial perfusion syndrome: one twin develops at the expense of the other

o  Fetus Papyraceus/Vanishing twin – death and subsequent reabsorption of one fetus

·        Complications:  all complication rates are increased

o  Maternal:

§  Pre-eclampsia: 3* risk

§  APH: 6% (4 – 5% in singleton), PPH: 10% (4 – 6 % in singleton)

§  Preterm labour: on average 3 weeks early

§  Mal-presentation: only 40% present cephalic/cephalic

§  Hypertension

§  Gestational Diabetes

§  Miscarriage

§  Iron and folate deficiency

§  Acute polyhydramnios

o  Fetal:

§  Fetal growth retardation (~500 g less than expected in 25%) 

§  ­Still births and infant mortality

§  ­Congenital malformations, mental retardation and neurological damage

·        Management:

o  More regular monitoring: eg hypertension and diabetes

o  Iron, folate supplementation

o  Introduction to multiple pregnancy support groups

o  Hospital delivery: obstetrician, midwife, 2* paediatrician, etc

o  Aim for vaginal delivery of first twin, syntocinon after delivery of first