Presentation

1. Multifoetal gestation

2. • Multifoetal pregnancies are associated with
increased risk for both mother and child, and
• this risk increases with the number of offspring
• For example, 60 percent of twins, 90 percent of
triplets, and virtually all of quadruplets are born
preterm (Martin, 2012)
• From these observations, it is apparent that
women were not intended to concurrently bear
more than one offspring

3. Burden-US
• 1 in 80 (Corsello, 2010)
• Twinning rate was 32.1 per 1000 live births in 2009 (Martin, 2012)
• The rate of triplets or more was 138 per 100,000 births in 2010
(Martin, 2012)
• About a fourth of VLBW neonates are from multifoetal gestations,
and
• 15 percent infant mortality are from multifoetal pregnancies
(Martin, 2012)
• In 2009, the IMR for multiple births was five times the rate for
singletons (Mathews, 2013)

4. Mechanism of twinning
• Multifoetal pregnancies may result from
• a single fertilization followed by an “erroneous” splitting of
the zygote ie Monozygotic=1 in 250 ie 1/3 or
• two or more fertilization events ie Dizygotic or
fraternal=2/3
• Dizygotic twins are not in a strict sense true twins because
they result from the maturation and fertilization of two ova
during a single ovulatory cycle or
• a combination of both

6. Genesis of monozygotic twinning
• Minor trauma to the blastocyst
• The outcome of the monozygotic twinning process
depends on when division occurs
• If zygotes divide within the first 72 hours after
fertilization,
• two embryos,
• two amnions, and
• two chorions develop,
• and a diamnionic, dichorionic twin pregnancy evolves
• Two distinct placentas or a single, fused placenta may
develop

7. • If division occurs between the fourth and eighth
day, a diamnionic, monochorionic twin pregnancy
results
• By approximately 8 days after fertilization, the
chorion and the amnion have already
differentiated, and division results in two
embryos within a common amnionic sac, that is,
a monoamnionic, monochorionic twin pregnancy
• Conjoined twins result if twinning is initiated later

8. • It has long been accepted that
monochorionicity incontrovertibly indicated
monozygosity
• Rarely, however, monochorionic twins may in
fact be dizygotic (Hack, 2009)
• Mechanisms for this are speculative, but
Ekelund and coworkers (2008) found in their
review of 14 such cases that nearly all have
been conceived after ART procedures

11. Antenatal diagnosis
• Lack of visualization of an intertwin
membrane
• Cord entanglement
• Visualization of one yolk sac with two fetal
poles
• Presence of one placental disk
• Same-sex fetuses

12. • Pseudo-monoamniotic twins — The term
pseudo-monoamnionicity has been used to
describe diamniotic twin pregnancies in which
the intertwin membrane has ruptured
• When this occurs, it is usually a complication
of amniocentesis or other invasive fetal
procedures [11,42-45], although it may occur
spontaneously
Antenatal diagnosis ct

13. Prenatal diagnosis
• The diagnosis should be suspected in first-trimester monoamniotic twin
pregnancies when the embryonic/fetal poles are closely associated and do not
change in position with respect to each other (image 2) [102-104]
• Fusion of fetal organs may be obvious (image 3).
• Other findings, which are not all specific to conjoined twins, include
• juxtaposed embryos with a single midline cardiac motion
• increased nuchal translucency or cystic hygroma
• no sign of separate movement of the twins
• a single umbilical cord with more than three vessels
• fewer limbs than expected
• inseparable fetal parts
• hyperextension of the cervical spines of fetuses who face each other, or
• both heads or breeches consistently at the same level to each other [105,106]
• In the latter half of pregnancy, a detailed anatomy survey can aid in defining the
location and extent of the conjoined area

14. Superfetation and Superfecundation
• In superfetation, an interval as long as or longer than a menstrual
cycle intervenes between fertilizations
• Superfetation requires ovulation and fertilization during the course
of an established pregnancy, which is theoretically possible until the
uterine cavity is obliterated by fusion of the decidua capsularis to
the decidua parietalis
• Although known to occur in mares, superfetation is not known to
occur spontaneously in humans
• Lantieri and colleagues (2010) reported a case after ovarian
hyperstimulation and intrauterine insemination in the presence of
an undiagnosed tubal pregnancy
• Most authorities believe that alleged cases of human superfetation
result from markedly unequal growth and development of twin
fetuses with the same gestational age

15. • Superfecundation refers to fertilization of two ova
within the same menstrual cycle but not at the same
coitus, nor necessarily by sperm from the same male
• An instance of superfecundation or heteropaternity,
was documented by Harris (1982)
• The mother was sexually assaulted on the 10th day of
her menstrual cycle and had intercourse 1 week later
with her husband
• She was delivered of a black neonate whose blood type
was A and a white neonate whose blood type was O
• The blood type of the mother and her husband was O

17. Vanishing twin
• In one analysis of 41 cases of spontaneous reduction, higher values
of pregnancy-associated plasma protein A (PAPP-A) and free β-
human chorionic gonadotropin (β-hCG) were identified (Chasen,
2006)
• Gjerris and colleagues (2009) compared 56 cases of “vanishing
twin” to 897 singletons after ART and did not identify any
differences in first-trimester serum markers as long as the reduction
was identified before 9 weeks
• If diagnosed after 9 weeks, the serum markers were higher and less
precise than in singleton ART gestations
• Therefore, the diagnosis of vanishing twin should be excluded to
avoid confusion during maternal serum screening for Down
syndrome or neural-tube defects (Chap. 14, p. 283)

18. Factors That Influence Twinning
• Increasing maternal age
• ART

19. Timing of delivery
• The optimum time to deliver uncomplicated twin
pregnancies depends on chorionicity and amnionicity
• However, spontaneous or medically indicated
preterm birth complicates over 50 percent of twin
pregnancies; thus, scheduling the timing of delivery
is not at the discretion of the obstetrician in most
cases

20. Timing of delivery ct
• Dichorionic/diamniotic twins – We suggest planning
delivery of uncomplicated dichorionic/diamniotic
twins at 38+0 to 38+6 weeks of gestation (Grade 2C)
• Monochorionic/diamniotic twins – We suggest
planning delivery of uncomplicated
monochorionic/diamniotic twins at 36+0 to 36+6
weeks of gestation (Grade 2C)
• Monochorionic/monoamniotic twins –
Monochorionic/monoamniotic twins are delivered
earlier

21. • Cesarean birth is preferred for
1. monoamniotic twins,
2. diamniotic twins with a noncephalic-presenting twin
3. diamniotic twins with a cephalic-presenting twin
<28/40 and
4. pregnancies with standard obstetric indications for
cesarean birth (eg, placenta previa)
Indications for C/S

22. Choosing the route of delivery in
diamniotic twins

23. Route of delivery
• The optimum route of delivery depends largely on
presentation (algorithm 1)
• Cephalic/cephalic diamniotic twins – For cephalic/cephalic
diamniotic twins, we suggest vaginal delivery in the
absence of standard indications for cesarean delivery
(Grade 2B)
• Cephalic/noncephalic diamniotic twins – For
cephalic/noncephalic diamniotic twins, we suggest a trial of
labor and breech extraction of the second twin only if the
obstetrician has the requisite experience and if the patient
provides informed consent (Grade 2C)
• Noncephalic presenting twin – When the first twin is not in
cephalic presentation, we suggest cesarean delivery (Grade
2C)

24. TOLAC
• While we offer a trial of labor after a previous
cesarean (TOLAC) to patients with twins and one
prior cesarean delivery, there are few data to
evaluate the safety of TOLAC with twins and ≥2 prior
cesarean deliveries
• We advise repeat cesarean delivery for these
patients, but some providers may make this decision
on a case-by-case basis, allowing a trial of labor
selectively and with very close maternal-fetal
monitoring

25. Labour
• Cervical ripening – Use of cervical ripening methods and
oxytocin dosing for induction and augmentation are the same as
in singleton pregnancies
• Fetal heart rate monitoring – The fetal heart rate of each twin
can be monitored using a single machine with dual-channel
capability (waveform 1)
• If two separate monitors are used, their internal clocks must be
synchronized, paper speeds must be identical, and contractions
must be displayed on both fetal heart rate tracings
• Analgesia/anesthesia – Neuraxial analgesia/anesthesia provides
good pain relief, does not cause neonatal depression, and is an
appropriate anesthetic if uterine manipulation (eg, external or
internal version, breech extraction) or operative delivery (eg,
forceps, cesarean) becomes necessary

26. Delivery room
• We deliver all twin pregnancies in an operating room
where cesarean birth can be performed, if needed
• Cord clamping – Monochorionic twins are not
appropriate candidates for delayed cord clamping
because acute and large inter-twin blood transfusion
may occur during labor and delivery

27. Management of the second twin birth
• After birth of the first twin, the heart rate and
position of the second twin should be evaluated
using ultrasound and electronic fetal monitoring
• As long as the fetal heart rate tracing is reassuring,
there is no duration of elapsed time from birth of the
first twin that necessitates intervention to deliver the
second twin
• Six to 25 percent of second twins will be delivered
by cesarean after vaginal birth of the first twin

28. • Second twin cephalic – If the second twin is in a cephalic
presentation, oxytocin augmentation of labor is sometimes
necessary due to a temporary reduction in contraction
frequency after the first birth
• If the second twin is cephalic but unengaged, some
providers perform a controlled needle puncture of the
amniotic sac between contractions, and
• others perform internal podalic version and breech
extraction
• Second twin noncephalic – If the second twin is not in a
cephalic presentation (eg, breech or transverse), our
preference is breech extraction if there are no
contraindications to this procedure
Management of the second twin birth ct

29. • administering nitroglycerin (50 mcg
intravenously, may repeat in 60 seconds to a
maximum total dose of 250 mcg) or
inhalational anesthesia, both of which relax
uterine muscle
• Effective maternal analgesia is also crucial
• Extraction is performed as soon as feasible to
reduce the risk that the cervix will contract,
potentially entrapping the head
Management of the second twin birth ct