MULTIPLE GESTATIONS

VOLUME 32 • NUMBER 2 • JUNE 2005 v

CONTENTS

Preface xiKeith A. Eddleman and Joanne Stone

Epidemiology and Biology of Multiple Gestations 301Loraine Endres and Isabelle Wilkins

Twins have always aroused interest and have been representedthroughout history. Conjoined twins have caused even more sen-sation, the best-known pair being Chang and Eng Bunker, whowere born in Thailand in 1811 and inspired the term Siamese twins.Recently, higher-order multiples have caused controversy, and therehas been heavy media coverage of large-number deliveries, suchas the McCaughey septuplets. In this article, we review the incidence,types, and causes of multiple gestations.

Assisted Reproductive Technologies and Multiple Gestations 315Ellen E. Wilson

Since the first in vitro fertilization infant was born in England in 1978,the practice of assisted reproductive technology (ART) has steadilyincreased as the technology and success rates have improved. Theincidence of multiple gestations has also increased, primarily owingto the practice of transferring multiple embryos during an ART cycle.Guidelines for infertility clinics have been outlined, along with stra-tegies to limit the number of embryos transferred (depending onthe age of the patient) to achieve a lower risk of multiple births.Since 1997, a decrease has occurred in the number of embryos trans-ferred and the percentage of gestations with three or more fetuses,accompanied by a steady increase in the percentage of live birthsper cycle.

Ultrasound in Multiple Gestations: Twins and Other Multifetal Pregnancies 329Ana Monteagudo and Ashley S. Roman

Ultrasound has an important role not only in assessing amnionicityand chorionicity but also in diagnosing abnormalities and providingfetal surveillance throughout the duration of gestation.

Invasive Procedures in Multifetal Pregnancies 355Meredith Rochon, Keith A. Eddleman, and Joanne Stone

This review discusses the various invasive techniques currentlyperformed in multiple pregnancies.

Down Syndrome Screening in Twins 373Melissa C. Bush and Fergal D. Malone

Available methods for screening for Down syndrome (DS) in twingestations include maternal age, first-trimester nuchal translucency,first-trimester combined screening, second-trimester genetic sonog-raphy, second-trimester quad screening, and combinations of testsacross different gestational ages. Biochemical screening is generallyassociated with detection rates at least 15% less than in singletonpregnancies. Nuchal translucency measurement may help close thatgap, but the best available data (based on modeling) show approxi-mately 75% to 85% detection rates for DS, with a 5% false-positiverate. Patients accepting screening should be aware of all optionsshould a diagnosis of fetal aneuploidy be confirmed, including preg-nancy continuation, termination of the entire pregnancy, and selec-tive termination of an aneuploid fetus.

Management of High-Order Multiple Gestation 387John P. Elliott

High-order multiple gestation presents unique challenges to the cli-nician to obtain the best possible outcome. An aggressive proactiveapproach works best compared with a wait-and-treat strategy whencomplications occur. Frequent ultrasound evaluations, fetal fibro-nectin testing, and contraction monitoring are important diagnostictools. Aggressive weight gain, bed rest, and relaxation techniquesare important interventions. Tocolytic drugs are used to preventpreterm labor, and aggressive dosing of MgS04, terbutaline pumps,and oral agents are advocated to treat preterm labor. Outcome is generally good with high-order multiple gestation with this management protocol.

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Nutrition in Multiple Gestations 403Barbara Luke

Multiple pregnancies represent a state of magnified nutritionalrequirements, resulting in a greater nutrient drain on maternalresources and an accelerated depletion of nutritional reserves.Maternal weight gain to 20 weeks and between 20 and 28 weeks hasthe greatest effect on birthweight in twin and triplet pregnancies,particularly among underweight women. Parity, which most likelyrepresents a higher proportion of body fat, has a positive effect onpregnancy outcome, with an average 7 to 10 days longer gestationfor multiparous versus nulliparous women. In addition to being thenutrients most often lacking in a woman’s diet, calcium, magne-sium, and zinc have been identified as having the most potential forreducing pregnancy complications and improving outcomes.

Maternal Complications of Multifetal Pregnancy 431Cynthia Gyamfi, Joanne Stone, and Keith A. Eddleman

This article reviews the common maternal complications encoun-tered in multifetal gestations.

Antepartum Management of Multifetal Pregnancies 443Alisa B. Modena and Vincenzo Berghella

Correct antepartum management of multifetal gestations is a criti-cal skill for practitioners of obstetrics. This article reviews impor-tant issues surrounding these complicated pregnancies while discussing current management options and recommendations.Topics include antepartum surveillance, preterm labor prediction,diagnosis, and management, and special situations unique to mul-tiple gestations, such as twin-twin transfusion syndrome and deathof one twin in utero. It is the authors’ hope that this article is comprehensive in enhancing the reader’s knowledge of these complex pregnancies.

Intrapartum Management of Twins: Truths and Controversies 455Andrew J. Healy and Sreedhar Gaddipati

Twin gestations pose a challenge in management, and the intra-partum phase of care is not exempt. Despite increasing numbers of twin gestations, the literature does not adequately answer sev-eral basic questions regarding appropriate intrapartum manage-ment. This article provides an overview of the available literaturesupporting appropriate intrapartum actions in twin gestations andhighlights areas that are still awaiting further study, with the even-tual goal of optimizing intrapartum conditions, leading to animproved neonatal outcome.

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Monochorionic Twin Pregnancies 475Thomas Trevett and Anthony Johnson

The monochorionic placenta should be considered a developmentalmalformation and, as such, represents one of the most commonbirth defects. Great strides are being made to unravel the progres-sion of nature’s successful attempt at human cloning through fis-sion. Critical to any strategy to reduce the perinatal morbidity andmortality associated with monochorionic placentas is early detec-tion. Intense surveillance in at risk pregnancies will provide a betterunderstanding of their natural progression, improve the prognosiswith early intervention, and ultimately provide the key to preventmany of the complications unique to the monochorionic placenta.

Long-Term Outcomes in Multiple Gestations 495Larry Rand and Keith A. Eddleman

Children born from a multiple gestation are at increased risk forcerebral palsy, learning disability, and language and neurobehav-ioral deficits. With the increased incidence of multiple pregnanciesand use of assisted reproductive technology (ART), these issues aremore commonly affecting parents. Long-term outcomes are a criti-cal part of preconceptual and early pregnancy counseling for par-ents faced with a multiple gestation or considering ART, and theprovider should be well versed on issues surrounding zygosity,gestational age, higher-order multiples, and the effects of optionssuch as multifetal pregnancy reduction.

Index 515

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