European Journal of Cardiovascular Medicine

Multiple pregnancy is defined as pregnancy with 2 or more fetuses.It is termed as twins for 2 fetuses, triplets for 3 fetuses, Quadruplets for 4 fetuses, Quintuplets for 5 fetuses, Sextuplets for 6 fetuses and Septuplets for 7 fetuses and so on.The incidence of multiple pregnancies varies significantly among different regions, countries and populations. Multiples make up only about 3 in 100 births, but the multiple birth rate is rising.

In several overview studies (since the early 1970) it was found that natural twinning rates were less than 8 twin births per 1000 births in East Asia and Oceania, 9-16 per 1000 births in Europe, USA and India and 17 and more per 1000 births in African countries.^1-5 Smith et al reported that India has twining rates below 9 per 1000 births.⁶

Twins can be either monozygotic or dizygotic. Dizygotic twins or fraternal twins are formed due to fusion of two separate ova by two different sperms. The placenta is always dichorionic and diamniotic. Depending on the timing of splitting of fertilized egg, monozygotic twins can be dichorionic or monochorionic. When the splitting occurs, within 3 days of fertilization it results in the formation of dichorionic twins and when it occurs after 3 days, monochorionic twins are formed.

Rate of monozygotic twining is relatively constant (3.5-4 per 1000 births).¹ and it has no bearing with maternal age, race, parity and heredity. However, dizygotic twinning is affected by maternal age, maternal height, race, parity, heredity, smoking habit, use of oral contraceptives and use of assisted reproductive techniques (ART).^7-9

=The rate of perinatal mortality can be six times higher in twin pregnancies than singleton pregnancies. This is mostly due to higher rates of preterm delivery and fetal growth restriction seen in twin pregnancies.10,11 Preterm birth and birth weight are also significant determinants of perinatal morbidity and mortality into infancy and childhood.11 The incidence of twin pregnancy has been on rise recently due to advanced age of pregnancy and increasing use of assisted reproductive techniques. Low birth weight contributed by both prematurity and IUGR is the main factor responsible for higher perinatal mortality in twins. Major priorities in the management of twin gestations are early and accurate perinatal diagnosis, detection and management of maternal complications and fetal growth restriction.Planning the time and mode of delivery in complicated twin pregnancies and early detection of monochorionic placentation and managing its consequences are crucial steps leading to a higher probability of successful outcome. Size inequality of twin fetuses which can be a sign of pathological growth restriction in one fetus, is calculated using larger twin as the index. Generally as the weight difference between the twin pair increases, the perinatal mortality increases proportionately. Because the single placenta is not always equally shared in monochorionic twins, these twins have greater rates of discordant growth outside of monochorionic twins, these twins have greater rates of discordant growth outside of TTTS than dichorionic twins. It develops in approximately 15 percent of twin gestations. Restricted growth of one twin fetus usually develops late in the second and early third trimester. Earlier discordant indicates higher risk for fetal demise in the smaller twin specifically when discordant growth is identified before 20 weeks, fetal death occurs  in about 20 percent. Importantly differences in crown rump length are associated with fetal structural and chromosomal anomalies but are not reliable predictors for birth weight discordance.

A prospective study was carried out in all twin pregnancy women of second and third trimesters in department of Obstetrics and Gynaecology in Government maternity hospital from date of approval of scientific and ethical committee to one year. Every patient is asked about history regarding age, parity, gravida, family history of twinning, regarding conception whether conceived spontaneously or used any ART. Routine investigations were advised and chorionicity was assessed using placental examination on ultrasound. If any discordancy or any abnormality detected then patients were admitted and investigated and treated accordingly.The patients were followed upto delivery and gestational age noted at the time of delivery.Apgar score at 0 and 5 minutes noted. Birth weight noted.The babies were followed until day 28.Perinatal morbidity and mortality noted. Neonatal morbidity and mortality were noted. My study period is From 11 February 2021 to 11 February 2022.

On admission history of patients taken and following points were being noted:

• Age
• Parity
• Gravida
• Family History

On General Examination, following points were noted.

• Chorionicity was assessed using ultrasound and placental
• The perinatal outcome
• Gestational age at delivery (28–30 weeks, 31-33, 34-37, > 37 weeks).
• Mode of delivery (Caesarean section/ vaginal delivery/ combined/outlet forceps/ vacuum).
• Apgar score at 0 and
• Birth weight (> 2500 gms, 2500 – 1500 gms, < 1500gms).
• Neonatal morbidity were classified in septicaemia, growth restriction, respiratory distress syndrome, fetal growth restriction (FGR), neonatal hyperbilirubinemia (NNH), patent ductus arteriosus (PDA), hypoglycemia, anomalous baby, neonatal seizures(NNS).

STATISTICAL ANALYSIS

Following statistical methods were employed in the present study

• Frequencies
• Contingency Table analysis and
• Chi-square test

Table 1: Twin deliveries with relation to parity &chorionicity

Primigravidas constituted              for 43% of pregnancies and multigravidas  constituted for 57% of pregnancies.

Table 2: Twin deliveries with relation to maternal age

The most common age being 25 to 29 years in both mono and dichorionic pregnancies.

Table 3: Twin deliveries with relation to mode of conception

In our study, Most of the cases 83% belong to spontaneous conception, 15% were induced by drugs and 2% of cases were induced by IUI.

Table 4: Twin deliveries with relation to family history

Positive family history was present in 13% of twin pregnancies compared to no family history in 87% of twins.

Table 5: Twin deliveries with relation to chorionicity

In our study of 200 cases, 124 cases were (62%) were dichorionic diamniotic where as 76 cases (38%) were monochorionic

Table 6: Twin deliveries with relation to maternal risk factors

Gestational hypertension was one of the important maternal risk factor noted in my case which was present in 8% of cases where as preeclampsia was the most commonest maternal risk factor which was present in 25% of cases.

Table 7: Twin deliveries with relation to preterm and PROM

Preterm complicating twin pregnancies was present in 44% where as preterm PROM PPROM was present in 17% of cases. There was a stastical significance of preterm (P value of <.05(0.0003) and preterm PPROM (PPROM)(P value of <.05(0.0048)) between monochorionic and dichorionic pregnancies analysed using the Fischer’s exact test where as there was no significance in term and PROM between monochorionic and dichorionic pregnancies .

Table 8: Twin deliveries with relation to gestational age of delivery

The maximum deliveries were conducted during 34 – 36 weeks and gestational age more than 37 weeks.Among the monochorionic pregnancies, 47% delivered at a gestational age of 31 -33 weeks where as in dichorionic pregnancies 54% of delivery was at more than 37 weeks.

Table 9: Twin deliveries with relation to mode of delivery

The most commonest mode of method was LSCS delivery in both monochorionic pregnancies and dichorionic pregnancies followed by vaginal delivery.

Table 10 : Twin deliveries with relation to indications for LSCS

The most common indication for LSCS was fetal malpresentations in both monochorionic pregnancies (26.71%) and dichorionic pregnancies (24.19%).

Table 11 : Twin deliveries with relation to mode of presentation

The most common mode of presentation was vertex presentation in both monochorionic pregnancies and dichorionic pregnancies.

Table 12 : Twin deliveries with relation to PPH

The significance of PPH with relation to chorionicity was compared was using Fischer’s exact test and was not found to be significant with a P value of > 0.05.

Table 13: Twin deliveries with relation to intrauterine death and chorionicity

The significance in difference between the two groups was analysed using the Fischer’s test and was found significant with a P value of 0.157.

Table 14 : Twin deliveries with relation to stillbirth and chorionicity

The significance in difference between the two groups was analysed using the Fischer’s test and was not found significant.

Table 15 : Twin deliveries and chorionicity with relation to birth weight

The birth weight of 1.5-2.5 kg was noticed in 52% of cases in monochorionic pregnancies where as it was notice in 64 % of cases in dichorionic pregnancies.

The significance in difference between the two groups in low birth weight and very low birth weight was analysed using the Fischer’s test and was found significant with P value was found to be 0.0412 and 0.0026.

Table 16 : Twin deliveries with relation to congenital anomalies

The significance in difference between the two groups was analysed using the Fischer’s test and was found significant with P value was found to be 0.01.

Table 17: Twin deliveries with relation to IUGR

The significance in difference between the two groups was analysed using the Fischer’s test and was found significant with a P value of 0.0342

Table 18 : Twin deliveries with relation to apgar score

The significance in difference between the two groups was analysed using the Fischer’s test and was found significant with a P value of0.056.

Table 19 : Twin deliveries with relation to discordant growth

The significance in difference between the two groups was analysed using the Fischer’s test and was found significant with a P value of 0.0065

Table 20: Twin deliveries with relation neonatal morbidity

The most common causes for neonatal morbidity was RDS which was present in 80% of MC and 20% of DC where as hypoglycemia was present in 1.6 % of DC pregnancies.

Table 21: Twin deliveries with relation to neonatal mortality

Neonatal mortality was found in 15 cases ( 19.73%) in MCDA and MCMA where as 9 cases (8%) of DC.The significance in difference between the two groups was analysed using the Fischer’s test and was found significant with a P value of 0.039.

Table 22: Twin deliveries with relation to causes of neonatal mortality

The most common cause of neonatal mortality was RDS & sepsis in both monochorionic pregnancies and dichorionic pregnancies.

Table 23: Twin deliveries with relation to perinatal outcome of twin B

Primigravidas constituted for 43% of pregnancies and multigravidas constituted for 57% of pregnancies which was consistent with the study done by Feng B et al and azubike et al where in primigravidas were least compared to multigravida and twins are the most common type of multiple pregnancy and the more number of pregnancies, the more chances of having multiple pregancies.The findings were consistent with the study done by Su RN et al¹² who noted that multiple pregnancy were common in multigravidas and was significantly associated with older maternal age, caesarean delivery, preterm labor, GDM, hypertensive disorders, SGA, low birth weight (<2500 g) and NICU admission but was not associated with maternal height, PROM, and congenital malformations.

The most common age being 25 to 29 years in both monochorionic and dichorionic pregnancies which was in accordance with the study done by Aslam S et al¹³  whose study age group was between 21 and 29 years and the most common reason being this age is more fertile and as the age advances the twin pregnancy increases in 1.4% between 25 and 34, 3% between 34 and 39, and 4.1% in women in their 40s or over and also twin pregnancies are more common in pregnacies conceived through ART and the recent trend shows that women of this age are moving out of normal pregnancies to newer ART technique.

In my study, Most of the cases 83% belong to spontaneous conception, 15% were induced by drugs and 2% of cases were induced by IUI which was consistent with the study done by Aslam et al¹³   who noted

spontaneous conception being the most common mode of delivery . The mode of delivery in twin pregnancy depends on multiple factors and it is very important to determine the fetus presentation, fetal weight, maternal clinical conditions and also the number of pregnacies.Performing an elective cesarean delivery can be considered in mainly reducing maternal and neonatal morbidity and mortality and also preventing the maternal complications.

Positive family history was present in 13% of twin pregnancies compared to no family history in 87% of twins which was consistent with the study done by Hoeskstra C et al who noted that a positive family history in the form of stronger genetic predisposition and also study conducted by Meulemans et al¹⁴ revealedthat the inheritance was consistent with an autosomal dominant monogenic model with incomplete penetrance.

In my study of 200 cases, 124 cases were (62%) were dichorionic diamniotic where as 68 cases (34%) were monochorionic diamniotic where as 8 cases (4%) were monochorionic and monoamniotic which was consistent with the study done by Ratha C et al¹⁵ who noted that around 72 % were dichorionic diamniotic and the most common reason being Dichorionic twins are more commonly seen in people who have been for inertility treatments such as in-vitro fertilization (IVF) and also in women of advanced maternal age and in patients with family history of twin births.

Gestational hypertension was one of the important maternal risk factor noted in our case which was present in 8% of cases where as preeclampsia was the most commonest maternal risk factor which was present in 25% of cases which was in accordance with the study done by Dubey S et al16 who noted in 432 deliveries that risk factors were as preterm deliveries in 304 (70%), anaemia in 259(60%) patients, preterm rupture of membranes in 120 (39.4%) patients, hypertensive disorders of pregnancy in 122(28.3%) patients, cholestasis of pregnancy in 24(5.5%) of patients, hypothyroidism in 22(5.1%) of patients, antepartum hemorrhage (APH) in 20(4.6%) and gestational diabetes mallitus (GDM) in 08(1.8%) of patients and also study by Chaudhary et al¹⁷ concluded in his study that the most common risk associated were 22.6% for hypertension, 35.8% for anemia, 5.7% for APH and 5.7% for polyhydramnios. There was no significant difference in the presence of maternal risk factors among MC and DC pregnancies.

Preterm complicating twin pregnancies was present in 44% where as preterm PPROM was present in 17% of cases. There was a stastical significance of preterm (P value of <.05(0.0003) and preterm PPROM(P value of <.05(0.0048)) between monochorionic and dichorionic pregnancies analysed using the Fischer’s exact test where as there was no significance in term and PROM between monochorionic and dichorionic pregnancies which was in accordance to the study done by Sela H eta¹⁸ who noted that in his study of 49 twin pregnancies preterm complicating twin pregnacies was more than preterm PPROM.

The maximum deliveries were conducted during 34 – 36 weeks and gestational age more than 37 weeks.Among the monochorionic pregnancies, 47% delivered at a gestational age of 31 -33 weeks where as in dichorionic pregnancies 54% of delivery was at more than 37 weeks which was in consistent with the study done by Lee HJ etAl¹⁹ who noted that the optimal delivery time may be at or beyond 36 weeks for monochorionic twins, and at or beyond 37 weeks for dichorionic twins. Currently the optimal timing of delivery of twin pregnancy is still controversial, with some experts suggesting preterm or early-term delivery to avoid late stillbirth risk, while others support maintaining pregnancy to decrease the prematurity related neonatal morbidities. Some studies have suggested that twins mature faster than singletons, and therefore, may be better equipped for earlier delivery thus the lowest perinatal mortality rate for twins occurs at an earlier gestational age than singletons.

The most commonest mode of method was LSCS delivery in both monochorionic pregnancies and dichorionic pregnancies, followed by vaginal delivery which was in contrast to the study done by Chen H et al²⁰ who noted that in his study of 98 pregnancies, 44.9% were delivered via vaginal delivery and also concluded that women in the vaginal delivery group were significantly younger, multiparous and with more twins in vertex-vertex presentation compared with women in the Cesarean delivery group.The babies fetal position plays an important role for deciding of the presenting part of the first baby. Caesarean section is the most preferred method and also in some conditions like placenta praevia (a low-lying placenta) or twins sharing a placenta, caesarian section is the preferred method or the previous pregnancy had a very difficult delivery ,a caesarean section is the most preffered method with twins.

The most common indication for LSCS was fetal malpresentations in both monochorionic pregnancies and dichorionic pregnancies which was consistent with the study done by Hofmeyer GJ et al²¹ Which was in contrast with the study done by Unuigbe JA et al²² who noted that the main indications for cesarean section on the twin pregnancies were antepartum hemorrhage (placenta previa), malpresentation, cervical dystocia and previous cesarean section.

PPH as a complication was analysed and PPH was present in 22% in 36 monochorionic pregnancies and out of 62 dichorionic pregnancies it was present in 15%. The significance of PPH with relation to chorionicity was compared was using Fischer’s exact test and was not found to be significant with a P value of > 0.05 which was in accordance with the study done by Naushaba et al²³ who noted no significance of twin deliveries with relation to PPH.

The birth weight of 1.5-2.5 kg was noticed in 52% of cases in monochorionic pregnancies where as it was noticed in 64 % of cases in dichorionic pregnancies.The significance in difference between the two groups in low birth weight and very low birth weight was analysed using the Fischer’s test and was found significant with P value was found to be 0.0412 and 0.0026 Which was similar to the study done by Hatkar PA et al ²⁴who concluded that monochorionic twins had a lower birth weight compared to dichorionic twins.

Among monochorionic pregnancies, congenital anomalies were present in 6% and in 0.8% of DC pregnancies. The significance in difference between the two groups was analysed using the Fischer’s test and was found significant with P value was found to be 0.0128.The incidence of congenital anomalies were more in monochorionic pregnancies which was in accordance to the study done by Glinianaia SVet al25 who concluded that congenital anomalies were predominat in monochorionic pregnancies when compared to dichorionic pregnancies.

Neonatal mortality was found in 15 cases (19.73%) in MCDA and MCMA where as 9 cases (8%) of DC.The significance in difference between the two groups was analysed using the Fischer’s test and was found significant with a P value of 0.039 which was consistent with the study done by Bellizzi S et al⁷¹ who concluded that the neonatal mortality among twins was significantly higher when compared to singleton neonatesand attributed the fact that it was most commom among low- and middle- income countries compared to high income countries.

A multiple pregnancy can be defined as pregnancy with 2 or more foetuses.  Twins can be either monozygotic or dizygotic. Twin pregnancy are associated with higher rates of adverse neonatal and perinatal outcomes. The various risk factors associated are previous multiple pregnancy, family history (maternal side),Increasing maternal age. It is highly advisable to determine the chorionicity at 11-14 weeks of gestation as each type of placentation carries different prognosis and morbidity. Assessment of chorionicity helps in the management of discordant growth, twin to twin transfusion, feasibility of multifetal reduction and management of other complications. Early diagnosis of chorionicity and proper follow up throughout the gestation improves the perinatal outcome. Obstetric ultrasound evaluations for twin gestations are dependent on the definition of the chorionicity of the gestation. In dizygotic twin gestations, ultrasound at 16 weeks for fetal anatomy survey is appropriate, and after that, it should be done every 3 to 4 weeks for fetal growth and reaffirmation of the fetal anatomy. Monochorionic-Monoamniotic twins should always be delivered by cesarean section to avoid umbilical cord complications for the non- presenting twin at the time of the first twin's delivery. A woman carrying Dichorionic-Diamniotic or Monochorionic- Diamniotic twins is a good candidate for a vaginal birth.

1.Bulmer MG, The Biology of Twinning in Man. Oxford: Oxford UniversityPress;1970.

2.Little J, Thompson B Descriptive epidemiology. In: McGillivray I, Campbell DM, ThompsonBJ, editors. Twinning and Twins. New York:Wiley;1988:37-66.

3.Blickstein I, Keith LG multiple pregnancy, epidemiology, gestation and perinatal outcome, 2nded. London: Taylor andFrancis;2005.

4.Nylander PPS Frequency of multiple births.In: McGillivray I, Nylander PPS, Corney G,editors. Human Multiple Reproduction. London:Saunders;1975:87- 97.

5.Nylander PPS. The phenomenon of twinning. In: Barron SL, Thompson AM, editors.Obstetrical Epidemiology. London: AcademicPress;1983:143-65

6.Smits J, Monden C. Twinning across the developing World. PLoS ONE.2011;6(9):e25239.

7.Fauser BC, Devroey P, Macklon NS. Multiple birth resulting from ovarian stimulationfor subfertility treatment. Lancet.2005;365(9473):1807-16.