Multifetal Pregnancy Radha Venkatakrishnan Clinical Lecturer Warwick Medical School

Incidence : Monozygotic twins - 4/1000 births Dizygotic twins – 2/3rds, race, age, assisted conception Triplets – 1 in 7000 to 10,000 births Quadruplets – 1 in 600,000 births Almost every maternal and obstetric problem occurs more frequently in multiple Pregnancy Perinatal mortality rate in twins is 5 times higher and in triplets 10 times higher than in singletons

Zygosity refers to the type of conception Chorionicity denotes the type of placentation Chorionicity rather than zygosity determines out outcome Zygosity and Chorionicity

Mechanism of dizygotic twinning

Fertilization of a single ovum Similar sex Genetically identical Fertilization of 2 separate ova

Monochorionic twins Within 72 hours (18-32%) 3-8 days later (60-70%)

Monochorionic twins 8-12 days later (1-2%) days later (0.5%)

Maternal responses Cardiac output, GFR and renal blood flow Plasma volume by 1/3 > singletons Red cell mass 300 ml > singletons Hematocrit and hemoglobin Iron stores in 40% of women with twins Multiple pregnancy

Diagnosis Patient profile: Etiological factors: – positive past history and family history specially maternal, race, age – Assisted reproductive technology Early pregnancy: – Hyperemesis, excessive weight gain –  minor complications of pregnancy such as backache, edema, varicose veins, hemorrhoids, striae, etc

Physical signs General: – Pallor, weight gain, excessive pedal edema/ varicose veins –  Pregnancy Induced Hypertension(PIH) and Pre-eclampsia (5-10times more) Abdominal: – Size > Date especially in midpregnancy – Multiple fetal parts – Auscultation of FHS: – 2 different recordings by 2 observers and a difference > 10 bpm

Differential diagnosis Elevation of the uterus by a distended bladder Inaccurate menstrual history Hydramnios Hydatidiform mole Uterine fibroids A closely attached adnexal mass Fetal macrosomia (late in pregnancy)

Ultrasonography Detect multifetal gestation 99% before 26 weeks Confirm fetal number [ 2 sacs or 2fetal heads in 2 perpendicular planes] Diagnose type and presentation and position and relation to each other Exclude congenital abnormalities/ conjoint twin

Maternal complications Symptoms – hyperemesis, aches and pains of pregnancy worsen Hypertensive disease of pregnancy Preterm delivery Premature rupture of membranes Polyhydramnios Placenta praevia Malpresentation Delivery complications (operative delivery, placental abruption, cord accidents) Postpartum hemorrhage, depression

Fetal complications Spontaneous early pregnancy loss Prematurity Intra-uterine growth restriction Cerebral palsy - related to gestational age, 3 times in twins, > 10 times in triplets Intrapartum trauma Monochorionic twins – specific complications

Antenatal care Routine booking investigations Folic acid supplementation anemia – treat immediately Support symptomatically Serial growth scans : Dichorionic :4 weekly from 24 weeks Monochorionic : 2 weekly from 18 weeks - Liquor volume - Doppler study of umbilical artery

Intrapartum management Presence of skilled obstetrician, anesthetist and neonatologist available at delivery Reliable intravenous access Cardiotocograph with dual monitoring capability Portable ultrasound scanner Delivery bed with lithotomy stirrups Obstetric forceps or vacuum apparatus active management of third stage: Uterotonics Immediate availability of blood Facilities and staff for emergency cesarean section

Monochorionic Monoamniotic twins x perinatal mortality 10 x cerebral necrotic lesions 1% of monozygotic twins are monoamnionic Perinatal mortality rate of 30-50%, largely relates to a risk of intrauterine death before 32 weeks Cord entanglement

Twin-Twin Transfusion Syndrome Incidence : % of MC twins It is characterised by an imbalance of blood flow between the twins % of perinatal deaths Untreated, perinatal loss rates in the mid-trimester ( %)

Large volume amnioreduction

Amniotic Septostomy

Fetoscopic Laser Ablation

Delivery by Caesarean section at 34 weeks

Conjoined twins or Siamese twins Anterior (thoracopagus) Posterior (pygopagus) Cephalic (craniopagus) Caudal (ischiopagus)

Single intrauterine demise 2-6% of twins pregnancies Up to 25% in MC twin pregnancy Perinatal morbidity and mortality of the surviving co-twin - 19% perinatal death - 24% having serious long term sequelae

Treatment options No optimal management Prompt delivery -Iatrogenic prematurity risks Conservative treatment -Subsequent handicaps Intrauterine interventions

High order multiples Perinatal risk increases exponentially with increasing number of fetuses Multifetal pregnancy reduction (MFPR) at 10 to 12 weeks should be recommended for quadruplets and higher multiples The situation with triplets is more controversial