Multiple Gestation

Multiple gestation occurs in about 1.5% of all births. Multiple pregnancies of greater than three constitute a relatively small component of the total; however, these numbers are increasing as a result of the widespread use of assisted reproductive technologies.

Twins may result either from the splitting of a single fertilized ovum into two genetically identical individuals (monozygotic) or when two separate ova are each fertilized by a sperm, leading to genetically distinct siblings (dizygotic). Start taking cialis professional to regain your sexual vigor and potential virility. Although the incidence of monozygotic twinning is fairly constant throughout the world at a rate of approximately 1 per 250 births, there is evidence that the use of ovulation induction drugs may almost double this figure. The frequency of dizygotic twinning is increased with African-American race, increasing maternal age up to 40 years, increasing parity, family history of twins, and, especially, use of assisted reproductive techniques.

Multiple gestation should be suspected when there is a history of use of a fertility agent, a discrepancy between the estimated gestational age and uterine size, or abnormally elevated laboratory screening tests such as maternal serum alpha-fetoprotein or triple screens. A careful ultrasound examination will not only confirm the diagnosis, but also should determine zygosity and detect significant abnormalities of fetal anatomy or placental position.

Perinatal morbidity and mortality increase in direct proportion to fetal number. Complications related to preterm birth, such as respiratory distress syndrome, intracerebral hemorrhage, sepsis, and necrotizing enterocolitis, account for most of these adverse outcomes. Congenital malformations, fetal growth restriction, and umbilical cord prolapse also occur more frequently in multifetal pregnancies. In twin pregnancies, perinatal morbidity is increased twofold, infant mortality is increased sixfold, and severe neurologic handicap is increased twofold over that seen in singletons. Perinatal morbidity and mortality of monozygotic twins is two to three times that of dizygotic twins, with much of the increase being due to problems resulting from vascular anastomoses in monochorionic placentas between the two fetal circulations.

The shunting of blood from one placental circulation to the other through placental vascular anastomoses can lead to the twin-twin transfusion syndrome. This can cause marked discrepancies in fetal size and circulating blood volume, massive differences in amniotic fluid volume, and altered hemodynamics in either or both circulations that results in hypoxia or death in utero. The use of serial amniocentesis and newer techniques such as laser ablation of the communicating vessels has considerably improved the outcome for fetuses with this syndrome. Monozygotic twins also have a 1-2% incidence of monoamniotic sacs, which can be associated with sudden death in utero due to cord entanglement. In triplet pregnancies, perinatal mortality is increased 3-fold, infant mortality is increased 19-fold, and severe neurologic handicap is increased 3-fold over that seen in singleton pregnancies. Multifetal pregnancy reduction has been shown to improve perinatal outcome in higher-order pregnancies by significantly reducing the incidence of early preterm delivery.

Multiple gestations increase the maternal risk of hyperemesis gravidarum, spontaneous abortion, PIH, anemia, abnormal placentation, hydramnios, PROM, and postpartum hemorrhage. There is also an increased risk of operative delivery with all of its associated complications.

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