INCIDENCE higher-order births attributable to IVF. (4) In

INCIDENCE OF TWINS
AND TYPE OF TWINS:

 

A
comparative prospective study conducted for 18 months by Singh et al with 9843 total deliveries with 179 twin deliveries
giving the incidence of 1.85%.Most of the twins were dichorionic diamniotic
(65%).Monochorionic diamniotic constituted 32%.One case was monchorionic and
monoaminotic and one conjoined twin. 2

 

In
a study by Pandey et al which was a prospective observational study for
2years where a total of 144 multiple pregnancies out of 7666 had delivered with
the overall incidence of 1.9 per 1000 births during the study period. There
were 5 triplet pregnancies among these. There were 93(67%) dichorionic twins
and 46(33%) monochorionic twins. Also incidence of monozygotic twins is same
throughout the world that is 3.5 per 1000 live births, incidence of dizygotic
twins is affected by multiple factors like ART and varies from 4 to 50 per 1000
live births. (3)

 

Whereas
Kulkarni et al estimated that by
2011, a total of 36% of twin births and 77% of triplet and higher order births
resulted from conception assisted by fertility treatments. The observed
incidence of twin births had increased by a factor of 1.9 from 1971 to 2009.
The incidence of triplet and higher-order births increased by a factor of 6.7
from 1971 to 1998 and decreased by 29% from 1998 to 2011. This decrease
coincided with a 70% reduction in the transfer of three or more embryos during
IVF and a 33% decrease in the proportion of triplet and higher-order births
attributable to IVF. (4)

 

In
a study by Nwankwo et al there were 5298 deliveries within the study
period, out of which 117 were twin deliveries which gives a twinning rate of 22
per 1000 deliveries.(5)

 

 Also Fell
et al study showed twin live births in the United States increased from
23.1 in 1991 to 32.2 per 1000 live births in 2004, remained stable between 2004
and 2007 and then increased slightly to an all-time high of 33.2 per 1,000 live
births in 2009. In Canada, rates also increased from 20.0 in 1991 to 28.3 per
1,000 live births in 2004, continued to increase modestly between 2004 and
2007, and rose to a high of 31.4 per 1,000 in 2009. Rates of triplet live
births in the United States increased dramatically from 81.4in 1991 to 193.5
per 100,000 live births in 1998, remained stable between 1998 and 2003 and then
decreased to 148.9 per 100,000 in 2007. The rate declined marginally in 2008,
but then rose again in 2009 to 153.5 per 100,000. Rates of triplet+ live births
were much lower in Canada, although the temporal pattern of change was similar.
(6)

 

In
a study by Qazi et al there were a
total of 161 multiple pregnancies with the overall incidence of 37.1 per 1,000
births (3.2%) during the study period. 38(31%) were monochorionic twins. (7)

 

PRESENTATION OF TWINS:

 

In
a prospective comparative study by Singh
et al showed that the most common presentation was vertex for both the
twins (48%) followed by 1st breech second vertex (20%). Next in order was 1st
vertex and 2nd breech (13.33%) and both breech (8%). Those with shoulder
presentation were few. (2)

 

Pandey et al prospective observational
study among 144 twins for two years showed most common presentation was
vertex-vertex 85(61%),followed by vertex-breech 20(14.3%),breech vertex
18(13%),breech-breech 11(8%),and vertex-transverse 5(3.5%).(3)

 

Nwankwo et al study
showed predominant fetal presentation in both twin 1(62.4%) and twin 2(59.8%)
is cephalic. (5)

 

Qazi et al cross
sectional observational study in 161 twin pregnancies suggested commonest
presentation is vertex vertex(51%) followed by vertex breech (24%),breech
vertex(15%) and breech breech (10%).(7)

 

 

MODE OF DELIVERY:

 

Singh et al included
prospective comparative study of twins versus singletons out of which
spontaneous vaginal delivery was seen in 62.6% of twins and 77.3% of
singletons. Assisted vaginal delivery with forceps was seen in 4.67% of twins
and 4% of singletons. Higher rates of LSCS seen in twin pregnancies as compared
to singletons (32.67% versus 18.67%). (2)

 

Pandey et al concluded that the
commonest mode of delivery out of 144 twins, was vaginal 75(54%) of first twin
and 72(52%) of second twins 64(46%) had LSCS and 3 had LSCS for second twin delivery,
whereas 3 triplets were delivered by caesarean section and two vaginally. (3)

 

In
a study by Nwankwo et al there were 5298 deliveries within the study
period, out of which 117 were twin deliveries. Fifty-nine women (50.4%) had
vaginal deliveries, 5 (4.3%) had vaginal delivery of the leading twin and
caesarean delivery of the retained second twin while 53 women (45.3%) were
delivered by caesarean section. The commonest indications for caesarean section
were abnormal lies and presentations and hypertension in pregnancy. (5)

 

Whereas
Qazi et al concluded there were a
total of 161 multiple pregnancies, of which most common route of delivery was
caesarean section (53.3%).(7)

 

ACOG quoted that in a
retrospective study conducted in tertiary referral centre from 2009 to
2015,2484 twins were studied 69.3% delivered by cesarean section, combined
delivery rate was 1.3%.(8)

 

Vogel et al included 1,424 twin
pregnancies, of these 25.9% had a non-vertex second twin and Caesarean was more
common in non-vertex presentations. (9)

 

The best method to deliver when presenting twin is cephalic still
remains controversial as concluded by Christopher
et al. The fact that second twin may change its position after delivery of
first twin is considered. In this study there is no difference in outcome from
ECV and IPV. So two factors to be considered are obstetricians need to be
prepared for and skilled in breech extraction and individualized patient
counseling. (10)

 

MATERNAL
COMPLICATIONS IN TWIN PREGNANCY:

 

MISCARRIAGE:

 

Joó et
al study showed spontaneous abortion is 7.3% in multiple pregnancies. Monochorial
placentation was more prone. Out of 44 cases of spontaneous abortion, 27
conceived naturally and 17 through ART. (11)

 

ANEMIA IN TWIN
PREGNANCY:

 

Singh et al comparative study
showed that anemia was found in 33 twins (44%) and 16 singletons (21.33%). (2)

 

Pandey et al observed 144 twins
and 8.6% had anemia among them. (3)

 

 Study by
Nwankwo
et al observed
pregnancy complications of anemia in 9.4% of women among twins. (5)

 

 In a study by Qazi et al, out of 161 twins, 74.6% had anemia. (7)

 

PREGNANCY INDUCED
HYPERTENSION:

 

Singh et al included
prospective comparative study out of which 32% of twins developed pregnancy
induced hypertensive disorders out of which gestational hypertension comprised
7%,preeclampsia 11% and eclampsia 6% of patients while in singleton
pregnancies, incidence of hypertensive disorders was 17.33% of which
gestational hypertension and preeclampsia each was seen in 6.67% and eclampsia
in 4%.(2)

 

Pandey et al had 5%of PIH out
of 144 multiple pregnancies. Eclampsia was seen in two cases. (3)

 

Study
by Nwankwo
et al observed
pregnancy complications of severe hypertension were 17 (14.5%) out of 117 twin
deliveries. (5)

 

In
a study by Qazi et al there were a
total of 161 multiple pregnancies in which pregnancy-induced hypertension were
40 (30%). (7)

 

A
study by Fox et al included 513 twin
pregnancies, 76(14.8%) developed preeclampsia. Risk factors independently
associated with preeclampsia were egg donation and pre pregnancy obesity. (12)

 

Oger et al studied six hundred and twenty dichorionic and 155
monochorionic Twin Pregnancies where in case of monochorionic twin pregnancy
mothers had higher rates of pregnancy-related hypertension and hospitalization.
(13)

 

ANTE PARTUM
HEMORRHAGE:

 

Singh et al comparative study
between single ton and twin pregnancies showed no difference in APH between the
two groups. (2)

 

Pandey et al observed 2.2% of ante
partum hemorrhage among 144 twin pregnancies. (3)

 

 Study by
Nwankwo
et al observed
pregnancy complications of APH in 2.7% among 117 twin deliveries. (5)

 

PRETERM LABOUR:

 

Singh et al in a prospective
comparative study concluded that in twin pregnancies74.75% delivered preterm, while
25.3% among singleton pregnancies delivered preterm. (2)

 

Pandey et al observed 62.58% of
preterm deliveries out of 144 multiple pregnancies. (3)

 

In
a study by Nwankwo et al, out of 117 twin deliveries, forty eight (41%)
women were admitted into the hospital for preterm labor. (5)

 

In
a study by Qazi et al there were a
total of 161 multiple pregnancies, preterm delivery was 31%. (7)

 

More
than 50% of the twins were born preterm and almost all the triplets were born
preterm was concluded by Martin et al (14)

 

POST PARTUM
HEMORRHAGE:

 

Incidence
of PPH in twin gestation was 10 (13.33%) while in singletons was
6(8%).Requirement of blood transfusion was significant in twin gestation (40%)
as compared to singletons (16%) concluded by Singh et al.(2)

 

Pandey et al observed 144 twin
pregnancies 12 patients developed PPH. (3)

 

Study
by Nwankwo et al observed pregnancy
complications of PPH among 8.5% in 117 twin deliveries. (5)

 

In
a study by Qazi et al there were a
total of 161 multiple pregnancies and PPH occurred in 9(11.5%) and secondary PPH
occurred in 6 cases (4.9%). (7)

 

FETAL COMPLICATIONS
IN TWIN PREGNANCY:

 

LOW BIRTH WEIGHT:

 

In Singh et al  comparative study between twins and
single tons low birth weight  is  seen in 78.67% of twins as against to
singletons 29 babies that is 38.67%. Among twins 60 out of 75 first baby of
twins (80%) and 58 out of second baby of twins (77.33%) were low birth weight. Maximum
percentage of twins had birth weight between 1.5kg-2Kg. Mean weight of first
twin was 2.03kg and for second twin it was 1.98kg. For singletons mean weight
was 2.70. (2)

 

In
Pandey et al, study 53% of twins had
low birth weight. (3)

                   

INTRA UTERINE
GROWTH RESTRICTION:

 

In
Singh et al comparative study 24% of
twins and 12% of singletons were IUGR. (2)

 

NICU admission
rate:

 

Singh et al comparative study
showed there was higher incidence of moderate to severe asphyxia in twins as
compared to singletons. Higher rate of NICU admissions were seen in twins
(34.67%) as compared 18.67% in singletons .First baby of twin required NICU
admission in 22 out of 75 cases (29.33%) while second baby required the same in
30 out of 75 cases (40%).(2)

 

Also
in a study by Nwankwo et al out of 117 twin deliveries, the rate of new
born admissions in twin 1 was however higher in those delivered by Caesarean
section (39.6%) than those delivered vaginally (29.7%). Indications for
admissions into the special baby care units were; prematurity 33 (40.2%), birth
asphyxia 15 (18.3%), low birth weight 12 (14.6%), neonatal jaundice 10 (12.2%),
and twin-twin transfusion 4 (4.9%). (5)

 

PERINATAL
MORTALITY:

 

Very
high perinatal mortality was observed in twins in a comparative study by Singh et al, 27 out of 150 (18%) and in
singletons, it was 6 (8%). Perinatal mortality rate of monchorionic pregnancy
was 30% and it was 10.2% for dichorionic pregnancy which shows a significant
association of perinatal mortality rate and chorionicity. Non- vertex
presentation was associated with higher perinatal mortality rates than vertex
presentations. Second twin had a slightly higher mortality rate 21.33% compared
to first twin14.67%. No significant difference was seen in mortality rate, when
the delivery interval between two twins is increased. (2)

 

In
a study by Pandey et al, there were
a total of 27(96.4 per 1000 births) perinatal deaths which included 22 neonatal
deaths and 5 stillbirths. There were 9 neonatal deaths among the first twin and
10 neonatal deaths among the second twin. There was 1 stillbirth among the
first twin and 4 stillbirths among the second twin. (3)

 

Also
in a study by Nwankwo et al There was a higher rate of early neonatal
death in both vaginally delivered twin 1 (9.4%) and twin 2 (11.9%) than those
delivered by Caesarean section, 3.8 and 3.5%, respectively. There were 107 live
births and 10 still birth in twin one and 110 live births and 7 still births in
twin 2.Seventeen babies died in the early neonatal period, 8 and9 of twin 1 and
twin 2, respectively. Nineteen (55.9%)cases of still birth and early neonatal
deaths babies were delivered to un booked mothers giving perinatal mortality of
463/1000 while 15 (44.1%) of these were by booked mothers giving perinatal
mortality of 197/1000. (5)

 

In
a study by Qazi et al there were a
total of 161 multiple pregnancies, most common neonatal complication was low
birth weight. Prematurity was the most common cause of neonatal death with perinatal
mortality rate of 172 per 1000 births in this study. Among 244 twin babies,
there were 42 perinatal deaths which included 30 stillborn and 12 neonatal
deaths. In 30 stillborn fetuses, cases were equal for first and second twin
while 2 more second twin had early neonatal death as compared to the first
twin. Neonatal mortality decreased as gestation advanced suggesting prematurity
to be the main cause for higher perinatal mortality. Sepsis was responsible for
6 neonatal deaths and congenital malformation i.e. severe neural tube defects
for 10 cases. (7)

 

A
retrospective study conducted in tertiary referral centre from 2009 to
2015,2484 twins were studied 69.3% delivered by cesarean section, combined
delivery rate was 1.3%,second of twin was more likely to have poorer outcomes
than first twin including lower birth weight(2.39kg versus 2.43kg),higher rates
of APGAR<7 at 1minute (58.5% versus 53%),Neonatal death (1.4% versus 0.5%).However twin 1 is more likely to be admitted in NICU(47.2% Vs 41.5%),but once admitted second twin stay was longer(19.4 vs 17.3 days  was stated in ACOG.(8)     Vogel et al showed 279,425 mothers gave birth to 276,187 (98.8%) singletons and 6,476 (1.2%) twins, in which Odds of severe adverse maternal outcomes (death, blood transfusion, ICU admission or hysterectomy) and perinatal mortality in twin pregnancies were higher, however early neonatal death and stillbirth did not reach significance.(9)     Oger et al studied six hundred and twenty dichorionic and 155 monochorionic twin pregnancies, newborns from monochorionic twin pregnancies  had higher morbidity for very preterm birth (birth before 33 weeks gestation), very low birth weight (birth weight<1500g), Apgar <7 at 1 minute  and hospitalization. Perinatal mortality was also significantly higher, as well intrauterine fetal death and concluded that the study confirms that few differences exist among dichorionic and monochorionic TP with regard to maternal morbidity, while neonatal morbidity and mortality are higher in twins born from monochorionic pregnancies. (13)   In another study by Smith et al, overall, there were six deaths of first twins and 30 deaths of second twins. The odds ratio for death of the second twin due to intra partum anoxia was 21. (15)   Helmerhorst et al studied that singleton pregnancies from assisted reproduction have a significantly worse perinatal outcome than non-assisted singleton pregnancies, but this is less so for twin pregnancies. In twin pregnancies, perinatal mortality is about 40% lower after assisted compared with natural conception. (16)