The study was conducted on 106 twin pregnancies and 212 neonates. Based on the estimated fetal weights between 20 and 24 weeks of gestation, pregnancies were divided into 95 concordant and 11 discordant weight twin pregnancies. And according to the estimated fetal weights between 28 and 32 weeks of gestation, pregnancies were divided into 90 concordant and 16 discordant weight twin pregnancies.
Table 1 shows the comparison of maternal characteristics and pregnancy-related complications in the concordant and discordant groups using weights at 20–24 weeks of gestation. Between the two groups, no statistically significant differences were observed in maternal age (32.58 ± 4.15 vs 34.18 ± 5.03, p = 0.095) and BMI (pre-pregnancy, 22.33 ± 3.59 vs 23.02 ± 3.35, p = 0.393). However, in the concordant group, significantly more nulliparous cases (77.89% vs 63.64%, p < 0.001) and pregnancies through ART (70.53% vs 63.64%, p = 0.034) were confirmed. No significant differences in gestational diabetes (17.89% vs 0%, p = 0.063), threatened preterm delivery (46.32% vs 36.36%, p = 0.508), premature amniotic membrane rupture (PROM) (14.74% vs 9.09%, p = 0.695), and postpartum bleeding (2.11% vs 0.00%, p = 0.978) were observed between the two groups. However, the frequencies of preeclampsia (9.47% vs 27.27%, p = 0.032) and placenta previa (2.11% vs 18.81%, p = 0.002) were significantly higher in the discordant group compared with the concordant group. No differences in the cause of delivery were observed between the two groups.
Table 1
Comparison of maternal characteristics and pregnancy-related complications between concordant and discordant twins at 20–24 weeks of gestation in DCDA twins.
|
Concordant twin
(n = 95)
|
Discordant twin
(n = 11)
|
p value
|
Age (years)
|
32.58 ± 4.15
|
34.18 ± 5.03
|
0.095
|
Nulliparous, n (%)
|
74 (77.89%)
|
7 (63.64%)
|
< 0.001*
|
Prepregnant BMI (kg/m2)
|
22.33 ± 3.59
|
23.02 ± 3.35
|
0.393
|
BMI at delivery (kg/m2)
|
27.62 ± 3.88
|
28.25 ± 3.45
|
0.465
|
ART, n (%)
|
67 (70.53%)
|
7 (63.64%)
|
0.044*
|
Preeclampsia, n (%)
|
9 (9.47%)
|
3 (27.27%)
|
0.032*
|
Gestational diabetes, n (%)
|
17 (17.89%)
|
0 (0.00%)
|
0.063
|
Placenta previa, n (%)
|
2 (2.11%)
|
2 (18.81%)
|
0.002*
|
Threatened preterm, n (%)
|
44 (46.32%)
|
4 (36.36%)
|
0.508
|
PROM, n (%)
|
4 (14.74%)
|
1 (9.09%)
|
0.692
|
Postpartum bleeding, n (%)
|
2 (2.11%)
|
0 (0.00%)
|
0.978
|
Cause of delivery
|
|
|
0.533
|
Elective, n (%)
|
45 (47.37%)
|
5 (45.45%)
|
|
Spontaneous, n (%)
|
33 (34.74%)
|
3 (27.27%)
|
|
Iatrogenic, n (%)
|
17 (17.89%)
|
3 (27.27%)
|
|
DCDA, dichorionic diamniotic; BMI, body mass index; ART, artificial reproductive technique; PROM, premature rupture of amniotic membrane. *p values of < 0.05 are shown in bold with an asterisk (*) |
Table 2 shows the comparison of neonatal outcomes in both groups classified using weights at 20–24 weeks of gestation. No statistically significant differences were observed in gestational age at delivery (weeks, 35.70 ± 1.63 vs 35.80 ± 1.37, p = 0.778), gender (male, 58.42% vs 59.09%, p = 1.000), and birth weights (grams, 2322.11 ± 411.26 vs 2323.64 ± 500.94, p = 0.987). Moreover, no differences were observed in the 1- and 5-minute Apgar scores of 7 or less (13.68% vs 4.55%, p = 0.193, 0.00% vs 4.55%, p = 0.160, respectively), and NICU hospitalization (64.21% vs 68.18%, p = 0.894). The frequency of actual weight discordancy at delivery (17.89% vs 54.55%, p < 0.001) and developmental delay (3.68% vs 18.18%, p = 0.017) were higher in the discordant group, whereas oxygen supply treatment (42.63% vs 18.18%, p = 0.038) was higher in the concordant group. No significant differences were observed in neonatal morbidity, intubation, the use of a ventilator, RDS, sepsis, PDA (patent ductus arteriosus), and ROP (retinopathy of prematurity).
Table 2
Comparison of neonatal outcomes between concordant and discordant twins at 20–24 weeks of gestation in DCDA twins
|
Concordant twin
(n = 190)
|
Discordant twin
(n = 22)
|
p value
|
Gestational age at delivery (weeks)
|
35.70 ± 1.63
|
35.80 ± 1.37
|
0.778
|
Gender, male, n (%)
|
111 (58.42%)
|
13 (59.09%)
|
1.000
|
Birthweight (grams)
|
2322.11 ± 411.26
|
2323.64 ± 500.94
|
0.987
|
Weight discordancy at delivery, n (%)
|
34 (17.89%)
|
12 (54.55%)
|
< 0.001*
|
Apgar score at 1 min (< 7), n (%)
|
26 (13.68%)
|
1 (4.55%)
|
0.193
|
Apgar score at 5 min (< 7), n (%)
|
0 (0.00%)
|
1 (4.55%)
|
0.160
|
NICU admission, n (%)
|
122 (64.21%)
|
15 (68.18%)
|
0.894
|
Neonatal morbidity, n (%)
|
47 (24.74%)
|
1 (4.55%)
|
0.061
|
Intubation, n (%)
|
9 (4.74%)
|
1 (4.55%)
|
0.944
|
Ventilator use (nasal cPAP), n (%)
|
59 (31.05%)
|
4 (18.18%)
|
0.315
|
O2 supply, n (%)
|
81 (42.63%)
|
4 (18.18%)
|
0.047*
|
Phototherapy, n (%)
|
39 (20.53%)
|
5 (22.73%)
|
1.000
|
Developmental delay, n (%)
|
7 (3.68%)
|
4 (18.18%)
|
0.017*
|
DCDA, dichorionic diamniotic; NICU, neonatal intensive care unit. *p values of < 0.05 are shown in bold with an asterisk (*) |
Table 3 shows the comparison of the maternal characteristics and pregnancy-related complications in both groups categorized using weight discordancy at 28–32 weeks of gestation. In the discordant group, more ART trials (67.78% vs 81.25%, p = 0.041) were observed, but no significant differences in maternal age, parity, and BMI were observed. Preeclampsia was more prevalent in the discordant group (8.89% vs 25.00%, p = 0.019) but no significant differences in the frequency of placenta previa (3.33% vs 6.25%, p = 0.768) were detected. Moreover, the frequency of iatrogenic cause of delivery was higher in the discordant group (14.44% vs 43.75%, p < 0.001). No significant differences in the incidences of gestational diabetes or PROM or threatened preterm labor were detected between the two groups.
Table 3
Comparison of maternal characteristics and pregnancy-related complications between concordant and discordant twins at 28–32 weeks of gestation in DCDA twins
|
Concordant twin
(n = 90)
|
Discordant twin
(n = 16)
|
p value
|
Age (years)
|
32.53 ± 4.05
|
33.94 ± 5.25
|
0.158
|
Nulliparous, n (%)
|
67 (74.44%)
|
14 (87.5%)
|
0.263
|
Prepregnant BMI (kg/m2)
|
22.40 ± 3.62
|
22.38 ± 3.31
|
0.976
|
BMI at delivery (kg/m2)
|
27.76 ± 3.89
|
27.23 ± 3.57
|
0.471
|
ART, n (%)
|
61 (67.78%)
|
13 (81.25%)
|
0.041*
|
Preeclampsia, n (%)
|
8 (8.89%)
|
4 (25.00%)
|
0.019*
|
Gestational diabetes, n (%)
|
16 (17.78%)
|
1 (6.25%)
|
0.169
|
Placenta previa, n (%)
|
3 (3.33%)
|
1 (6.25%)
|
0.768
|
Threatened preterm, n (%)
|
40 (44.44%)
|
8 (50.00%)
|
0.697
|
PROM, n (%)
|
11 (12.22%)
|
4 (25.00%)
|
0.102
|
Postpartum bleeding, n (%)
|
2 (2.22%)
|
1 (3.12%)
|
1.000
|
Cause of delivery
Elective, n (%)
Spontaneous, n (%)
Iatrogenic, n (%)
|
48 (53.33%)
29 (32.22%)
13 (14.44%)
|
2 (12.50%)
7 (43.75%)
7 (43.75%)
|
< 0.001*
|
DCDA, dichorionic diamniotic; BMI, body mass index; ART, artificial reproductive technique; PROM, premature rupture of amniotic membrane. *p values of < 0.05 are shown in bold with an asterisk (*) |
Table 4 shows the comparison of neonatal outcomes between the two groups categorized based on weight discordancy at 28–32 weeks of gestation. Compared with the concordant group, the discordant group had earlier gestational age at delivery (35.93 ± 1.40 vs 34.47 ± 2.07, p < 0.001), lower birth weights (2379.22 ± 370.29 vs 2001.88 ± 533.51, p < 0.001), and higher NICU admission (60.56% vs 87.50%, p = 0.006). Moreover, discordant twins required intubation (2.78% vs 15.62%, p = 0.007), the use of a ventilator (25.56% vs 53.12%, p = 0.003), oxygen supply therapy (36.11% vs 62.50%, p = 0.009), and photo therapy due to hyperbilirubinemia (16.67% vs 43.75%, p = 0.001) more often compared with concordant twins. Developmental delays between 1 and 2 years after birth were also more frequent in the discordant group (2.22% vs 21.88%, p < 0.001).
Table 4
Comparison of neonatal outcomes between the concordant and discordant twins at 28–32 weeks of gestation in DCDA twins
|
Concordant twin
(n = 180)
|
Discordant twin
(n = 32)
|
p value
|
Gestational age at delivery (weeks)
|
35.93 ± 1.40
|
34.47 ± 2.07
|
< 0.001*
|
Gender, male, n (%)
|
104 (57.78%)
|
20 (62.50%)
|
0.760
|
Birthweight (gram)
|
2379.22 ± 370.29
|
2001.88 ± 533.51
|
< 0.001*
|
Weight discordancy at delivery, n (%)
|
22 (12.22%)
|
24 (75.00%)
|
< 0.001*
|
Apgar score at 1 min (< 7), n (%)
|
19 (10.56%)
|
8 (25.00%)
|
0.049*
|
Apgar score at 5 min (< 7), n (%)
|
0 (0.00%)
|
1 (3.12%)
|
0.328
|
NICU admission, n (%)
|
109 (60.56%)
|
28 (87.50%)
|
0.006*
|
Neonatal morbidity, n (%)
|
36 (20.00%)
|
12 (37.50%)
|
0.051
|
Intubation, n (%)
|
5 (2.78%)
|
5 (15.62%)
|
0.007*
|
Ventilator use (nasal cPAP), n (%)
|
46 (25.56%)
|
17 (53.12%)
|
0.003*
|
O2 supply, n (%)
|
65 (36.11%)
|
20 (62.50%)
|
0.009*
|
Phototherapy, n (%)
|
30 (16.67%)
|
14 (43.75%)
|
0.001*
|
Developmental delay, n (%)
|
4 (2.22%)
|
7 (21.88%)
|
< 0.001*
|
NICU, neonatal intensive care unit; RDS, respiratory distress syndrome; PDA, patent ductus arteriosus; IVH, intraventricular hemorrhage; PVL, periventricular leukomalacia; ROP, retinopathy of prematurity; NEC, necrotizing enterocolitis; BPD, bronchopulmonary dysplasia. *p values of < 0.05 are shown in bold with an asterisk (*) |
Figure 1 shows the results of the regression analysis to determine whether the estimated fetal weight discordancy in twin pregnancy could predict the occurrence of preeclampsia and placenta previa. The results were calculated after adjusting for the confounding factors of maternal age, pre-pregnancy BMI, BMI at delivery, and gestational age at delivery. The incidence of preeclampsia was confirmed by an odds ratio of 5.474 (95% CI, 1.682–17.811; p = 0.005) for discordancy between 20 and 24 weeks of gestation and an odds ratio of 2.961 (95% CI, 0.958–9.159; p = 0.059) for discordancy between 28 and 32 weeks of gestation. Moreover, placenta previa was predicted by the risk of odds ratio of 7.400 (95% CI, 1.562–35.056; p = 0.012) for discordancy between 20 and 24 weeks of gestation and an odds ratio of 2.087 (95% CI, 0.313–13.908; p = 0.447) for discordant twins between 28 and 32 weeks.
Figure 2 shows the results of the regression analysis to determine neonatal outcomes, including the use of a ventilator and the presence of developmental delay based on discordancy during pregnancy. The results were calculated after adjusting for the confounding factors of neonatal birth weight, gestational age at delivery, and NICU admission. The use of a ventilator was predicted by the odds ratio of discordancy between 20 and 24 weeks was 0.356 (95% CI, 0.086–1.471; p = 0.154) and the odds ratio of discordancy between 28 and 32 weeks was 1.232 (95% CI, 0.408–3.722; p = 0.711). Developmental delay was predicted by the risk of odds ratio of 8.047 (95% CI, 0.874–34.599; p = 0.005) for discordancy between 20 and 24 weeks and odds ratio of 11.113 (95% CI, 2.650–46.597; p = 0.001) for discordancy between 28 and 32 weeks.