Facts About Twins

The facts about twins and their formation.
I. Incidence: Approximately 1 in 80 pregnancies. Accounts for 20% of babies born < 1500 grams.

II. Risk Factors:

A. Size greater than dates
B. Elevated maternal serum alpha-fetoprotein
C. Strong maternal family history
D. Fertility Drugs.

III. Diagnosis: Ultrasound required for definitive diagnosis.

IV. Perinatal Morbidity & Mortality:

A. Overall perinatal mortality (PNM) 10 x higher than singletons
B. PNM for dichorionic twins is 9%
C. PNM for monochorionic twins is 26%
D. PNM for nonamniotic twins is 50%
E. Increased morbidity and mortality due to:

1. Prematurity: 50% of twins weigh less than 2500 gm.
2. IUGR: 30-50% incidence

Virtually all obstetric complications (with the notable exception of post-datism) are increased with multiple gestation.

V. Complications:


1. Premature labor
2. Congenital malformations - twice as high as singletons
3. Higher spontaneous abortion rate
4. Higher incidence of IUGR
5. Higher incidence of maternal anemia
6. Twin-to-twin transfusion syndrome
7. Pregnancy induced hypertension
8. Hydramnios


1. Placenta previa
2. Abruptio placenta
3. Vasa previa
4. Dysfunctional or prolonged labor
5. Abnormal fetal presentation
6. Cord prolapse
7. Higher incidence of cesarean section


1. Greater incidence of maternal blood transfusions
2. Postpartum hemorrhage/uterine atony

VI. Antepartum Management:

A. All pregnancies complicated by multiple gestation are Ahigh risk@ and need specialized antepartum, intrapartum, and postpartum care and management.

B. Encourage bed rest beginning at 20 weeks with twins, earlier with triplets.

C. Patients must be instructed as to signs and symptoms of premature labor, premature rupture of membranes and preeclampsia.

D. Screen for diabetes (1 hour glucola) at time of diagnosis and repeat at 26-28 weeks. May screen earlier and more often with positive family history.

E. Serial ultrasounds (q 4 weeks) for fetal growth and to detect discordancy. When suboptimal fetal growth or discordancy is suspected, (> 25% difference in estimated fetal weight) then perform ultrasounds at increased intervals.

F. Antepartum fetal surveillance NST/Biophysical profiles beginning approximately 32 weeks or earlier if indicated by superimposed problems (discordant growth, IUGR, Hydramnios, hypertension, etc).

VII. Intrapartum Management:

A. Delivery should occur at a hospital with the appropriate level of care (Obstetric and Pediatric). In preterm gestations (< 37 weeks) maternal transport to Tertiary Center for delivery should be considered.

B. Two obstetricians should be available for delivery.

C. Anesthesia personnel should be available in the Delivery Room.

D. Appropriate personnel skilled in neonatal resuscitation should be present in the Delivery Room (one pediatrician and one nurse for each neonate).

E. Continuous fetal monitoring must be employed on all fetuses, preferably with an internal catheter, an electrode on Twin A and external monitor (ultrasound) on Twin B or other fetuses.

F. Cesarean section is advisable for all breech-vertex and other abnormal presentations (interlocking twins) and for all pregnancies with three or more fetuses.

G. Be prepared for postpartum hemorrhage, i.e. oxytocin use postpartum, large-bore IV=s in place, blood available for transfusion.

H. Placenta and membranes should be examined and sent to Pathology.


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