8-multiple Pregnancy

Multiple Pregnancy

Multiple Pregnancy • 3% of all pregnancies • Account for 1 in 8 of perinatal deaths mostly as a result of prematurity.

Multiple Pregnancy • Twins • Triplets • Quadriplets

1:100------65% increase 1:10,000 ----500% increase 1:750,000---- 500 % increase

Etiology of Multiple Fetuses • Dizygotic: Fertilization of two separate ova, (fraternal twins). Two thirds • Monozygotic: Fertilization of a single ovum (identical twins) Triplets or more may have a mixture of both di & monzygotic.

Genesis of Monozygotic Twins

Frequency of Twins • Monozygotic: – 1/250 births, relatively constant worldwide – Independent of race, heredity, age, and parity • Dizygotic: – Doubled following ovulation induction – Influenced remarkably by race, heredity, maternal age, parity, and especially, fertility drugs • Incidence underestimated because of abortions or vanishing twin

Frequency of Twins • Induction of ovulation – Increases both mono & dizygotic twining – Gonadotropins - risk 20-40% – Clomiphine - risk 7% twins, 0.5% triplets, 0.3 quadruplets

Risk Facotrs • Race – Blacks > White – Africans • Heredity – Maternal transmission is stronger than paternal. • Maternal Age & Parity • Maternal size

Determination of Zygosity • Why important? – Assessing obstetrical risks – Guiding management – Inter-twin organ transplantation later in life

Determination of Zygosity • Ultrasound – High resolution ultrasound especially in first trimester – Fetal sex, separate placental sites, and dividing membrane relationships.

Determination of Zygosity • Placental examination – One common amnionic sac or if juxtaposed amnions not separated by chorion the infants are monozygotic.

Determination of Zygosity • Placental examination – If adjacent amnions are separated by chorion, the fetuses may be monozygotic, but more often are dizygotic

Determination of Zygosity • Sex – Twins of opposite sex are almost always dizygotic • Blood group • DNA Zygosity may not determined in 35% of twin sets

Diagnosis of Multiple Fetuses • Suspected if – Large for date uterus – Recent administration of either clomiphene or pituitary gonadotropin – Familial history of twins- weak clue

Diagnosis of Multiple Fetuses • Ultrasound – Detection of two separate fetal echoes with fetal heart activities visualized simultaneously

Other Diagnostic Aids • Unreliable methods: – Palpation of fetal Parts – Fetal Heart Sounds – Level of β hCG – Level of α -fetoprotein

Maternal Adaptation • Blood volume- mean increase amounts to about 50-60% with twins compared to 40-50% in singleton gestations, i.e. 500 mL greater • Cardiac output: Increased: – Increased pulse rate and stroke volume – Increased shortening fraction – Increased contractility

Maternal Adaptation • Uterus may reach a volume of 10 L or more and weigh in excess of 9 K especially if polyhydramnios is present. • Compression and displacement of abdominal viscera as well as the lungs • Obstructive uropathy which may lead to impairment of renal function

Fetal Complications • • • • • • • •

Abortions Malformations Prematurity Low birth weight Growth Discorcance Twin-twin transfusion syndrome Death of one/both fetuses Conjoined and acardiac twin

Morbidity and Mortality in Multiple Gestation Characteristic

Twins

Triplets

Quadruple ts

Average birth weight

g 2,347

g 1,687

g 1,309

Average gestational age at delivery wk 35.3

wk 32.2

wk 29.9

Percentage with growth restriction 25–14

60–50

60–50

Percentage requiring admission to neonatal intensive care unit

25

75

100

Average length of stay in neonatal intensive care unit

days 18

days 30

days 58

Percentage with major handicap

—

20

50

Risk of cerbral palsy

4 times more than 17 times more — singletons than singletons

Risk of death by age 1 year

7 times higher than singletons

times higher 20 than singletons

—

Maternal Complications • • • • • • •

Anemia: Iron & folate deficiency Discomfort Hypertension Cesarean births Placental Abruption Postpartum hemorrhage Hospitalization

Congenital Malformations • • • •

Major- 2% vs. 1% in singleton Minor- 4% vs. 2.5% Aneuploidy Polyhydramnios – usually transient at midgestation – if persistent may indicate risk of anomalies

Low Birth Weight • • • • • • • •

Diminished nurture especially in 3rd trimester Preterm labor Placental insufficiency Vascular anastomoses Related to no. of fetuses More in monozygotes Gender influence Anomalies

ART pregnancies • Preterm delivery • Low birth weight • Perinatal mortality

Prematurity • The major reason for the increased risk of neonatal death and morbidity in twins • Mostly due to spontaneous preterm labour (PTL) • Medically Indicated PTL: HBP, IUGR, abruptio

Unique Complications • • • • • •

Discordant twins Vascular communications between fetuses Death of one fetus Monoamnionic twins Conjoined twins Acardiac twin

Discordant Twins • Incidence 10% • Significant if >25% weight difference, larger twin is the index • Perinatal mortality & morbidity increased • Related to neurological disability later in life • Discordancy in dichorionic twins is due to placental insufficiency • Discordancy in monochorionic twins is due to hemodynamic imbalance of vascular anastomosis.

Vascular Communications • Nearly 100% of monochorial placentas have vascular anastomosis of variable number, size and direction – Artery-to-artery 75% – Vein-to-vein 50% – Artery-to-vein 50%

Vascular Communications • Most shunt are heniodynamically balanced • If unbalanced – Twin-twin transfusion syndrome – Acardiac twining

Twin Twin Transfusion Syndrome (TTTS) • Typically presents in midtrimester • Donor – Anemic – Growth restricted – Oligohydramnios • Recipient – Polycythemic – Circulatory overload (hydrops) – Polyhydramnios

Twin Twin Transfusion Sydnrome (TTTS) • Antenatal complications – Polyhydramnios-olighydramnios – Growth discordance & IUGR – IUFD of one/both twins – Preterm labor and delivery

Twin Twin Transfusion Sydnrome (TTTS) • Postnatal complications – Circulatory overload – Polycythemia – Hyperbilirubinemia and kernicterus – Heart failure – Hypervolemia and hyperviscosity – Occlusive thrombosis – Death

Death of One Fetus • Risk of maternal disseminated intravascular coagulation (consumptive coagulopathy) • Risk of consumptive coagulopathy to a surviving fetus theoretically higher if anastomosis present

Monoamnionic Twins • Rare variety of monozygotic twins (1%) • Extremely high fetal death rate, mostly due to cord interwining • Prophylactic cesarean delivery at 32-33 weeks is controversial

Conjoined Twins • Siamese twins, after Chang and Eng Bunker of Siam (Thailand) • After the embryonic disc and the rudimentary amnionic sac have been formed • Incidence unestablished – 1/60,000 births • Surgical separation may be successful if vital organs not shared

Antepartum Management • Diet – Energy sources increased by another 300 kcal/day. – Iron supplementation of 60 to 100 mg/day – Folic acid, 1 mg/day if inadequate protein intake

Antepartum Management • Antepartum Surveillance – serial sonography is usually employed throughout the third trimester – Nonstress test – Biophysical profile – Doppler study to assess feto-placental perfusion

Antepartum Management • Prevention of Preterm Delivery – Rest. Routine hospitalization is not recommended – Tocolysis: No significant benefit – Antenatal steroids: No proven benefit – Cerclage: No proven benefit • Pulmonary maturation at 32 weeks (34 in singletons): tested by lecithin-sphingomyelin ratio in amniotic fluid

Labor Complications • • • • • •

Preterm labor Uterine dysfunction Abnormal presentations Prolapse of the umbilical cord Premature separation of the placenta Postpartum hemorrhage

Intrapartum Management • • • •

Appropriately trained obstetrical attendant Continuous external/internal electronic fetal monitoring Blood transfusion products should be readily available Intravenous fluid infusion

Intrapartum Management • • • •

Skilled Obstetrician Anesthesiologist Two neonatal team, one skilled in resuscitation Adequate space in delivery area for maternal and infants management • Induction or stimulation of labor can be used with caution

Breech-Breech 5%

Others 8%

Cephalictransverse 18%

Cephalic-cephalic 42%

Cephalic-breech 27%

Intrapartum Management • Mode of delivery – Vaginal for cephalic-cephalic – Controversial for cephalic-non cephalic especially if prematurity is a concern – Increased rate of CS for second twin – Controversial for breech-cephalic because of rare risk of Locked twins

Intrapartum Management • Delivery of the second twin – Interval can be prolonged more than 30 minutes if continuous fetal monitoring is employed – Cesarean delivery rate is increased if interval is > 15 minutes – External cephalic version – Internal podalic version

External Cephalic Version

Internal Podalic Version

Triplets or More • Increased maternal physiological adaptation & complications • Survival improved for triplets (>95%) • Higher risk of prematurity • Risk of vaginal delivery • Cesarean is recommended