Multiple Gestations

Cynthia S. Shellhaas, MD, MPHAssociate Professor – ClinicalObstetrics & GynecologyCynthia.Shellhaas@osumc.edu

Objectives

To understand the epidemiology of multiple gestations

To be able to list and describe the most common maternal complications of multiple gestations

To be able to list and describe the most common fetal complications of multiple gestations

To describe an ante-partum plan for specialized care for multiple gestations

To describe a delivery plan for multiple gestations

Objective

To understand the epidemiology of multiple gestations

Twin Birth Rate—United States: 1980-2006

Twin Birth Rate: Maternal Age and Ethnicity

Objective

To be able to list and describe the most common maternal complications of multiple gestations

Physiologic Changes in Multiple Gestation

Increase in plasma volume related to fetal number (96% in triplets/48% in singletons)

Increased TV, O2 consumption, respiratory alkalosis

Increased placental massincreases in HPL, HCG, AFP, progesterone, estradiol

Increased energy demands

Maternal Complications: Hypertension

2-3 X increase (Twins:Singletons) Presents earlier in gestation Presents w/greater severity (BP elevations,

eclampsia) Increase in HELLP variant Twins more likely than singletons with same

condition to have PTD, LBW, or C/S Incidence does not vary with zygosity Higher order gestations: atypical presentations

more likely

Maternal Complications: GDM

Increased incidence in multiples/Increased HPL 3-6% twins 22-29% triplets Each fetus increases the risk by a factor of 1.8

Decreased incidence after pregnancy reduction Unknown: Ideal calories, optimal weight gain, oral

hypoglycemic agents in PCO patients, best fetal surveillance, or ideal delivery time

Maternal Complications: Other

Acute fatty liver 1 in 10,000 singleton deliveries; 14% of cases occur in

twins; 7% of triplet pregnancies Placental abruption

8.2 X increase (twins:singletons) Pruritic Urticarial Papules & Pustules of Pregnancy

0.2% singletons, 3% twins, 14% triplets Pulmonary Embolism

Increased C/S, bedrest, AMA Post-partum hemorrhage (atony)

Physiologic Change - Quiz

Antepartum Management: Diet

• Increase caloric consumption by 300 kcal/day/fetus over singleton; 600 kcal/day over non-pregnant woman

• Anemia– Iron deficiency anemia 2.4-4X higher– Folate deficiency anemia 8X higher

• Nutritional supplements– Iron (60-100 mg/day)– Folic acid (1 mg/day)

Weight Gain

BMI < 18.5 kg/m2: Insufficient data BMI 18.5-24.9 kg/m2: 37-54 lbs BMI 25-29.9 kg/m2: 31-50 lbs BMI > 30.0 kg/m2: 25-42 lbs

Recommedations for Supplemental Folic Acid

Objective

To be able to list and describe the most common fetal complications of multiple gestations

Relationship between Zygosity & Chorionicity

Gross specimen:  Dichorionic/diamniotic placenta

Ultrasound Assessment of Chorionicity

Twin Zygosity and Corresponding ComplicationsType Incidence IUGR PTD Placental

Vascular Anasomosis

Perinatal Mortality

Dizygotic 80 25 40 0 10-12

Monozygotic

20 40 50 ---- 15-18

Di/Di 6-7 30 40 0 18-20

Di/Mono 13-14 50 60 100 30-40

Mono/Mono < 1 40 60-70 80-90 58-60

Conjoined 0.002-0.008 ---- 70-80 100 70-90

Twin-Twin Transfusion Syndrome

Incidence: 10-15% of monochorionic/diamniotic twins Etiology: Artery-to-vein anastomoses Median GA at dx: 21 weeks Underlying cause of 16% of twin mortality

Twin-Twin Transfusion Syndrome

Williams’ Obstetrics, 22nd edition

Quintero Stages

1—Abnormal AFV levels; Donor has identifiable bladder 2—Collapsed bladder in oliguric donor 3—Abnormal doppler studies 4—Hydrops 5--Death

Monoamniotic Twins

Incidence: 1 in 10,000 pregnancies Twin-twin transfusion syndrome: 1% Monozygotic twins: 1-5% Increased fetal loss: 23%

Cord entanglement: 67%

Congenital anomalies: 26% NTD, abdominal wall, urinary malformations

Monochorionic/Monoamniotic Twins

Conjoined Twins

Ventral (87%) Parapagus (28%) Thoracopagus (19%) Omphalopagus (18%) Ischiopagus (11%) Cephalopagus (11%)

Dorsal (13%) Pygopagus (6%); craniopagus (5%); rachiopagus

(2%)

Ultrasound image:  Conjoined Twins

Conjoined Twins

Conjoined Twins

Twin Reversed Arterial Perfusion (TRAP) Sequence Incidence: 1 in 35,000 deliveries

1% monochorionic gestations Abnormal zygote division at time of twinning

Arterial-arterial anastamoses Donor (“pump”) twin perfuses recipient (“acardiac”) twin “Pump” twin: Heart failure, PTD

Weekly surveillance

Gross specimen:  TRAP Sequence

Division of a monozygote between the 4th & 8th day after fertilization creates which of the following?

A. Conjoined twins B. Diamnionic, dichorionic C. Diamnionic, monochorionic D. Monoamnionic, monochorionic

Monozygote Division

Morbidity/Mortality in Multiple Gestation

Twins Triplets Quadruplets

Avg BW 2,347 grams 1,687 grams 1,309 grams

Avg GA 35.3 wks 32.2 wks 29.9 wks

% IUGR 14-25 50-60 50-60

% NICU 25 75 100

Avg LOS 18 days 30 days 58 days

% HCP ----- 20 50

CP Risk 4X 17X -----

IM Risk 7X 20X -----

Objective

To describe an ante-partum plan for specialized care for multiple gestations

Antepartum Management: Fetal Growth

Similar rate of growth compared to singletons in 1st & 2nd trimesters; start to lag around 30-32 weeks’ Sub-optimal placentation Abnormal umbilical cord morphology/insertion Structural/genetic anomalies Monochorionicity

2006 Preterm Birth Rates: Twins vs. Singletons

Congenital Anomalies

MZ twins have a 2-3X increase compared to singletons/DZ twins Anencephaly Holoprosencephaly VATER association Extrophy of cloaca Sacrococcygeal teratoma Sirenomelia

Antepartum Management: Prenatal Diagnosis Dizygotic twins: independent & additive

aneuploidy risk The risk of having at least one affected fetus is

doubled Twin pregnancy in 33 year old has risk=35

year old with singleton Monozygotic twins: same risk as singletons

Prenatal Diagnosis

Ultrascreen MS-AFP Amniocentesis Chorionic villus sampling

Antepartum Management: Ultrasound

Assessment of chorionicity Level II Ultrasound Growth

Every 4-6 weeks if normal Evaluate interval growth every 10-14 days if

compromise Cervical length

Not before 16 weeks

What are these images?

Ultrasound images:  Cervical Length

Antepartum Management: Fetal Surveillance Increased risk for IUFD compared to singletons Both NST & BPP effective in identification of

compromised twins/triplets Questions

Higher order gestations GA to initiate testing Frequency: Once or twice weekly ? Normally growing dichorionic twins

Twins Questions

Objective

To describe a delivery plan for multiple gestations

Timing of Delivery

Most twins deliver between 35-36 weeks’ gestation Lung maturity Growth velocity Perinatal mortality & morbidity Best delivery time: 37-38 weeks’ gestation

Twins: Intra-Partum Management

Twin A VertexTwin B Vertex

Twin A Non-Vertex

Twin A VertexTwin B Non-Vertex

Vaginal DeliveryCesarean Delivery

CesareanDelivery External

Cephalic Version

BreechExtraction

UnsuccessfulSuccessful

Vaginal DeliveryCesarean Delivery

External Cephalic Version

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