Abstract
Objective
A unicornuate uterus is a type of Müllerian anomaly and is associated with adverse pregnancy outcomes. However, the perinatal outcomes of twin pregnancies in women with a unicornuate uterus remain unknown, and previous studies on women with a unicornuate uterus have focused mostly on those with singleton pregnancies. This research aimed to investigate the perinatal outcomes of twin pregnancies in women with a unicornuate uterus.
Methods
From January 2013 to December 2022, 283 women with a unicornuate uterus, including 21 with twin pregnancies (Group A), 262 with singleton pregnancies (Group B), and 105 with twin pregnancies and a normal uterus (Group C) were enrolled in this study and gave birth at West China Second University Hospital, Sichuan University. General characteristics and perinatal outcomes were retrospectively analysed using SPSS version 22.0.
Results
Among the 21 women with twin pregnancies and a unicornuate uterus, 20 (95.2%) had dichorionic diamniotic twins, and 1 (4.8%) had monochorionic diamniotic twins. Seventeen patients (81.0%) conceived by in vitro fertilization-embryo transfer (IVF-ET), and 4 patients (19.0%) conceived naturally. The mean gestational age at delivery was 33.8 ± 5.7 weeks, and 19 patients (90.5%) underwent caesarean section. The twin group (A) had significantly higher rates of preterm premature rupture of membranes (38.1%, 8/21), preterm delivery (85.7%, 18/21) (preterm delivery was defined as a birth occurring after 28 weeks and before 37 completed weeks of gestation), and neonatal intensive care unit (64.3%, 27/42) admission than Groups B and C (p < 0.05). Moreover, the live birth weight in Group A (1931.7 ± 535.2 g) was lower than that in Groups B and C (p < 0.001).
Conclusion
The incidence of complications and the risk of adverse perinatal outcomes in women with twin pregnancies and a unicornuate uterus are greater than those in women with singleton pregnancies and a unicornuate uterus and women with twin pregnancies and a normal uterus. Thus, maternal and foetal monitoring during pregnancy should be strengthened to achieve good outcomes.
Keywords: Müllerian anomalies, Unicornuate uterus, Twin pregnancy, Pregnancy outcomes
What does this study add to the clinical work
| Twin pregnancies in women with a unicornuate uterus is a rare condition that carries considerable risk for mothers and fetuses. Maternal and foetal monitoring during pregnancy should be strengthend to achieve good outcomes. |
Introduction
The female reproductive organs are affected by genetic or environmental factors during their formation and development, which may result in congenital anomalies of the genital organ [1]. A unicornuate or rudimentary uterus is formed due to the nondevelopment of one Müllerian duct, either partially or completely during the embryonic period [2]. The incidence of unicornuate uterus is approximately 0.1% in the general population, increasing to approximately 0.5% in women with infertility or miscarriage and accounting for from approximately 2.5%–13.2% of all uterine malformations [3]. Previous studies on women with a unicornuate uterus have focused mostly on those with singleton pregnancies, and studies have shown that the presence of a unicornuate uterus is associated with adverse pregnancy outcomes, including miscarriage, foetal growth restriction (FGR), preterm delivery (PTD), malpresentation, and higher rates of caesarean delivery [2, 4–7]. With the rapid development of assisted reproductive technology (ART), since the 1980s, the global twin birth rate has increased by one-third, varying considerably by region and country [8]. However, little is known about the effects of unicornuate uterine anomalies on twin pregnancies. To date, only a few studies on twin pregnancies in women with a unicornuate uterus exist, most of which have been published as case reports [9–11].
Hence, we conducted a 10-year retrospective cohort analysis of twin pregnancies in women with a unicornuate uterus and explored the effect of a unicornuate uterus on pregnancy outcomes. We hope our findings provide clinical recommendations and support for the perinatal management of twin pregnancies in women with a unicornuate uterus.
Materials and methods
This retrospective cohort study was conducted on singleton and twin-pregnant women who delivered at West China Second University Hospital between January 1, 2013, and December 31, 2022. Patients with severe medical and surgical complications or incomplete clinical information were excluded.
Pregnant women with a unicornuate uterus were divided into Groups A (twin-pregnant women with a unicornuate uterus) and B (singleton pregnant women with a unicornuate uterus). Twin-pregnant women with a normal uterus were selected by stratified equal-volume random sampling by age and included in Group C (control group).
There were 283 pregnant women with a unicornuate uterus, including 21 with twin pregnancies (Group A) and 262 with singleton pregnancies (Group B). One hundred and five twin-pregnant women with a normal uterus (Group C) (n = 105 (1:5)) were included in the control group (twin-pregnant women with a normal uterus were stratified according to maternal age). The optimal allocation of stratified random sampling was used to select a proportionate number of individuals from each stratum according to age in Group A. Unicornuate uterus was diagnosed according to the criteria of the European Society of Human Reproduction and Embryology (ESHRE), the European Society for Gynaecological Endoscopy (ESGE) and Chinese expert consensus [12–15]. Diagnostic methods include ultrasonography, hysterosalpingography, hysteroscopy and/or laparoscopy, and laparotomy. A unicornuate uterus is defined as unilateral uterine development, but the contralateral part can be either incompletely formed or absent. A unicornuate uterus can be divided into two classes: a unicornuate uterus with a functional rudimentary cavity characterized by the presence of a communicating or noncommunicating unilateral uterus and a unicornuate uterus with a nonfunctional or absent rudimentary uterus.
The characteristics and perinatal outcomes of the three groups were compared. The study was approved by the ethics committee of West China Second University Hospital (No. 2023-272).
Statistical analyses
Enumerated data are expressed as rates (percentages), and normally distributed quantitative variables are expressed as the means ± standard deviations. The chi-square test was used to determine significant differences between percentages, with continuity correction or Fisher’s exact test used where appropriate. Independent sample t tests were used to compare differences between means. Nonnormally distributed data (expressed as M [P25, P75]) between two groups were compared using the Mann–Whitney U test. A p value < 0.05 was considered significant. Statistical analyses were performed using SPSS version 22.0 (SPSS, Inc., Chicago, IL, USA).
Results
From January 2013 to December 2022, there were 131,913 patients who gave birth in our hospital, including 7002 women with twin pregnancies. Twin-pregnant women accounted for 5.3% (7002/131913) of all births, and the incidence of twin pregnancy in women with a unicornuate uterus was 0.3% (21/7002).
General characteristics
In the present study, 283 patients were diagnosed with a unicornuate uterus; 59.7% (169/283) of the patients were diagnosed before the current pregnancy, 17.0% (48/283) were diagnosed by ultrasound in the first trimester of the current pregnancy, and the remaining 66 patients (23.3%, 66/283) were diagnosed during delivery (caesarean section or vaginal delivery), including one patient diagnosed via ultrasound-monitored curettage for intrauterine pregnancy residue.
Among the 169 patients with a preconception diagnosis of a unicornuate uterus, 80 (47.3%, 80/169) were diagnosed by previous surgical exploration, including 40 diagnosed by hysteroscopy for infertility (8 patients with diagnosed with a rudimentary uterus during hysterectomy), 20 patients diagnosed intraoperatively during other gynaecological or surgical procedures, 16 patients diagnosed during previous caesarean section, and 4 patients diagnosed during emergency surgery for pregnancy. Seventy-seven patients (45.6%, 77/169) were diagnosed by ultrasound, and 12 cases (7.1%, 12/169) were diagnosed by hysterosalpingography.
Among the 283 patients, 129 had a left unicornuate uterus combined with a right rudimentary uterus (45.6%, 129/283), 106 had a right unicornuate uterus combined with a left rudimentary uterus (37.5%, 106/283), and 48 had a unicornuate uterus without a rudimentary uterus (16.7%, 48/283), including 36 with no rudimentary uterus and 12 with a previously removed rudimentary uterus (4 removed due to pregnancy in the rudimentary uterus and 8 removed during hysteroscopy and laparoscopy due to infertility).
Among all 283 pregnant women with a unicornuate uterus, 241 (85.2%, 241/283) delivered by caesarean section, and 42 (14.8%, 42/283) delivered vaginally (38 with eutocia, 4 with assisted vaginal delivery). Among the 241 women who underwent caesarean section, 187 had a unicornuate uterus with a rudimentary uterus, and 54 had a unicornuate uterus without a rudimentary uterus. Among all the rudimentary uteri found during caesarean section, only 1 had a functional endometrium, which was connected to the unicornuate uterus, and the remaining rudimentary uteri were muscular tissue. In ten patients, urinary tract malformations were detected.
Twenty-one twin pregnancies involved a unicornuate uterus, including 20 (95.2%) dichorionic diamniotic (DCDA) twin pregnancies and one (4.8%) monochorionic diamniotic (MCDA) twin pregnancy. Seventeen patients (81.0%) conceived by in vitro fertilization-embryo transfer (IVF-ET), and 4 patients (19.0%) conceived naturally. Among the twin-pregnant women with a normal uterus, 87 (82.9%) had dichorionic diamniotic (DCDA) twin pregnancies, and 18 (17.1%) had monochorionic diamniotic (MCDA) twin pregnancies. There was no statistically significant difference in the type of twin pregnancy between the two groups (p = 0.266).
The proportion of primigravida in the group of twin-pregnant women with a unicornuate uterus was greater than that in the group of singleton pregnant women with a unicornuate uterus (p = 0.033), and the other general characteristics were similar among the three groups (p > 0.05). Detailed information on the general characteristics of the patients is shown in Table 1.
Table 1.
General characteristics of the included participants
| Characteristics | Unicornuate uterus | Normal uterus | p | p (A vs. B) | p (A vs. C) | |
|---|---|---|---|---|---|---|
| Twins (n = 21) A | Singleton (n = 262) B | Twins (n = 105) C | ||||
| Maternal type | ||||||
| Primigravida, n (%) | 21 (100.0) | 204 (77.9) | 96 (91.4) | 0.001b* | 0.033b* | 0.353b |
| Multigravida, n (%) | 0 | 58 (22.1) | 9 (8.6) | |||
| Twin classification | ||||||
| DCDA twin, n (%) | 20 (95.2) | / | 87 (82.9) | 0.266b | ||
| MCDA twin, n (%) | 1 (4.8) | / | 18 (17.1) | |||
| Live neonatal | 42 | 260 | 208 | |||
| Male, n (%) | 19 (45.2) | 139 (53.5) | 95 (45.7) | 0.207 | 0.322 | 0.959 |
| Female, n (%) | 23 (54.8) | 121 (46.5) | 113 (54.3) | |||
| Diagnostic period | ||||||
| Progestation, n (%) | 13 (61.9) | 156 (59.5) | / | 0.696a | ||
| First trimester, n (%) | 2 (9.5) | 45 (17.6) | / | |||
| Delivery period, n (%) | 6 (28.6) | 60 (22.9) | / | |||
| Maternal age(year) | 23–36 | 20–45 | 23–44 | 0.677d | 0.786c | 0.533c |
| ≤ 24, n (%) | 1 (4.8) | 10 (3.8) | 3 (2.9) | |||
| 25–34, n (%) | 17 (81.0) | 210 (80.2) | 82 (78.1) | |||
| ≥ 35, n (%) | 3 (14.2) | 42 (16.0) | 20 (19.0) | |||
DCDA twin dichorionic diamniotic twin, MCDA twin monochorionic diamniotic twin
*p < 0.05
aThe Chi-squared test with Fisher’s exact test
bThe Chi-squared test with continuity correction
cMann–Whitney U-test
dKruskal–Wallis test
Perinatal outcomes of twin pregnancies in women with a unicornuate uterus
All 21 twin-pregnant women with unicornuate uterus (Group A) gave birth. The gestational age at delivery ranged from 28 weeks and 2 days to 37 weeks and 5 days. The mean number of gestational weeks at delivery was 33.8 ± 5.7, which included 19 women (90.5%) who underwent caesarean section, 1 woman (4.8%) with vaginal delivery, and 1 woman (4.8%) with assisted breech delivery.
There were 42 live births, including 13 live-born males (31.0%) and 29 live-born females (69.0%). Among the 27 neonates transferred to the neonatal intensive care unit (NICU), only one died, and the rest were discharged successfully. The neonate who died was delivered at 33 weeks and 6 days of gestation and had severe foetal growth restriction and congenital heart disease (narrowing of the aortic arch, ventricular septal defect) (birth weight 700 g with Apgar scores of 7 and 8 at 1 and 5 min, respectively); the neonate was transferred to the NICU after delivery, and the family abandoned treatment.
Comparisons between singleton pregnant women and twin-pregnant women with a unicornuate uterus
Two hundred and sixty-two cases of singleton pregnancies in women with a unicornuate uterus (Group B) gave birth. Group A had significantly higher rates of hypertensive disorder complicating pregnancy (HDCP) (19.0% vs. 4.6%, OR = 4.90, 95% CI 1.43–16.83), intrahepatic cholestasis of pregnancy (ICP) (28.6% vs. 6.1%, OR = 6.15, 95% CI 2.10–17.99), preterm premature rupture of membranes (PPROM) (38.1% vs. 11.5%, OR = 4.76, 95% CI 1.82–12.42), PTD (85.7% vs. 22.9%, OR = 20.20, 95% CI 5.75–70.91), NICU admission (64.3% vs. 12.3%, OR = 13.05, 95% CI 6.28–27.12), and ≥ 3 kinds of drugs used to promote uterine contraction (38.1% vs. 15.6%, OR = 3.32, 95% CI 1.29–8.51) than did Group B. In addition, birth weight was significantly lower in Group A than in Group B (1931.7 ± 535.2 g vs. 2964.8 ± 533.9 g, p < 0.001).
However, the rates of other perinatal complications and perinatal outcomes, including placenta previa, placenta percreta/accreta, placental abruption, PROM, malpresentation, an Apgar score of 5 min, postpartum hemorrhage (PPH) and uterine rupture (p > 0.05), were similar between the two groups. Detailed information is presented in Table 2.
Table 2.
Perinatal outcomes of the included participants
| Unicornuate uterus | Normal uterus | p (A vs. B) | OR (95% CI) | p (A vs. C) | OR (95% CI) | ||
|---|---|---|---|---|---|---|---|
| Twins (n = 21) A | Singleton (n = 262) B | Twins (n = 105) C | |||||
| Maternal complications | |||||||
| HDCP, n (%) | 4 (19.0) | 12 (4.6) | 28 (26.7) | 0.023b* | 4.90 (1.43–16.83) | 0.229 | |
| ICP, n (%) | 6 (28.6) | 16 (6.1) | 29 (27.6) | 0.001b* | 6.15 (2.10–17.99) | 0.929 | |
| DM (GDM and PGDM), n (%) | 6 (28.6) | 55 (21.0) | 26 (24.8) | 0.591b | 0.714 | ||
| Placenta previa, n (%) | 1 (4.8) | 10 (3.8) | 2 (1.9) | 0.579a | 0.424a | ||
| Placenta percreta/accreta, n (%) | 4 (19.0) | 55 (21.0) | 38 (36.2) | 1.000b | 0.128 | ||
| Placental abruption, n (%) | 0 | 3 (1.1) | 2 (1.9) | 1.000a | 1.000a | ||
| PROM, n (%) | 9 (42.9) | 72 (27.5) | 14 (13.3) | 0.134 | 0.004b* | 4.88 (1.74–13.67) | |
| PPROM, n (%) | 8 (38.1) | 30 (11.5) | 10 (9.5) | 0.002b* | 4.76 (1.82–12.42) | 0.002b* | 5.85 (1.96–17.49) |
| Oligohydramnios, n (%) | 1 (4.8) | 14 (5.3) | 1 (0.9) | 1.000b | 0.307a | ||
| Polyhydramnios, n (%) | 0 | 5 (1.9) | 10 (9.5) | 1.000a | 0.302b | ||
| Scarred uterus, n (%) | 0 | 45 (17.1) | 5 (4.8) | 0.078b | 0.589a | ||
| Malpresentation, n (%) | 10 (47.6) | 105 (40.1) | 46 (43.8) | 0.498 | 0.748 | ||
| IVF-ET, n (%) | 17 (81.0) | 50 (19.1) | 80 (76.2) | < 0.001* | 18.02 (5.81–55.89) | 0.850 | |
| Fetal complications | |||||||
| PTDs, n (%) | 18 (85.7) | 60 (22.9) | 58 (55.2) | < 0.001* | 20.20 (5.75–70.91) | 0.009*ara> | 4.86 (1.35–17.51) |
| < 37 weeks, n (%) | 8 (38.1) | 45 (17.2) | 43 (40.9) | ||||
| < 34 weeks, n (%) | 10 (47.6) | 15 (5.7) | 14 (13.3) | ||||
| < 28 weeks, n (%) | 0 | 0 | 1 (0.9) | ||||
| Live birth, n (%) | 42 (100.0) | 260 (99.2) | 208 (99.0) | ||||
| 5-min Apgar score | |||||||
| > 7, n (%) | 41 (97.6) | 260 (100.0) | 208 (100.0) | 0.139a | 0.168a | ||
| ≤ 7, n (%) | 1 (2.4) | 0 | 0 | ||||
| Live birth weight (g) | 1931.7 ± 535.2 | 2964.8 ± 533.9 | 2321.3 ± 517.8 | < 0.001d* | / | < 0.001d* | / |
| LBW ≥ 2500, n (%) | 9 (21.4) | 218 (83.8) | 76 (36.5) | ||||
| LBW < 2500, n (%) | 27 (64.3) | 39 (15.0) | 114 (54.8) | ||||
| VLBW < 1500, n (%) | 6 (14.3) | 3 (1.2) | 18 (8.7) | ||||
| NICU, n (%) | 27 (64.3) | 32 (12.3) | 50 (24.0) | < 0.001* | 13.05 (6.28–27.12) | < 0.001* | 5.69 (2.81–11.53) |
| Perinatal mortality, n (%) | 1 (2.4) | 2 (0.8) | 2 (1.0) | 0.363a | 0.425a | ||
| Intra-uterine death (IUD) | 0 | 1 | 0 | ||||
| Neonatal death | 1 | 0 | 2 | ||||
| Rivanol odinopoeia | 0 | 1 | 0 | ||||
| Mode of delivery | |||||||
| Cesarean section, n (%) | 19 (90.5) | 222 (84.7) | 99 (94.3) | 0.173a | 0.348a | ||
| Vaginal delivery, n (%) | 1 (4.8) | 37 (14.2) | 5 (4.8) | ||||
| Assisted vaginal delivery, n (%) | 1 (4.8) | 3 (1.1) | 1(0.9) | ||||
| Labor complications | |||||||
| Hemorrhage of delivery (ml) | 500 (400,600) | 400 (300,400) | 400 (300,500) | < 0.001c* | / | 0.019c* | / |
| PPH | 0 | 8 (3.1) | 7 (6.7) | 1.000a | 0.487b | ||
| Drugs to promote uterine contraction ≥ 3 kinds, n (%) | 8 (38.1) | 41 (15.6) | 59 (56.2) | 0.021b* | 3.32 (1.29–8.51) | 0.129 | |
| Uterine rupture, n (%) | 0 | 7 (2.7) | 2 (1.9) | 1.000a | 1.000a | ||
| Hysterectomy, n (%) | 0 | 1 (0.4) | 0 | 1.000a | / | ||
HDCP hypertensive disorder complicating pregnancy, ICP intrahepatic cholestasis of pregnancy, DM diabetes mellitus, GDM gestational diabetes mellitus, PGDM pregestational diabetes mellitus, IVF-ET in vitro fertilization-embryo transfer, PROM premature rupture of membranes, PPROM preterm premature rupture of membranes, PTDs preterm deliveries, NICU Neonatal Intensive Care Unit, IUD Intra-uterine death, LBW Live birth weight, FGR fetal growth restriction, PPH postpartum hemorrhage
*p < 0.05
aThe Chi-squared test with Fisher’s exact test
bThe Chi-squared test with continuity correction
cMann–Whitney U-test
dIndependent sample t-test
Comparisons between twin pregnancies in women with a unicornuate uterus and those with a normal uterus
One hundred and five twin-pregnant women with a normal uterus (Group C) were included in the study. Compared with Group C, Group A had significantly higher rates of PROM (42.9% vs. 13.3%, OR = 4.88, 95% CI 1.74–13.67), PPROM (38.1% vs. 9.5%, OR = 5.85, 95% CI 1.96–17.49), PTD (85.7% vs. 55.2%, OR = 4.86, 95% CI 1.35–17.51), and NICU admission (64.3% vs. 24.0%, OR = 5.69, 95% CI 2.81–11.53). Moreover, birth weight was significantly lower in Group A (1931.7 ± 535.2 g vs. 2321.3 ± 517.8 g, p < 0.05). (Table 2).
Discussion
A unicornuate uterus is a type of female genital malformation, and twin pregnancy in women with a unicornuate uterus is a rare condition that carries considerable risk for mothers and foetuses. A unicornuate uterus that is not combined with a rudimentary uterus with an endometrium usually causes no obvious clinical symptoms and is often difficult to detect; thus, the possibility of a unicornuate uterus should be considered in women with a history of infertility or adverse pregnancy outcomes [2–4]. In this study, the prepregnancy diagnosis rate reached 59.7% (169/283), and early diagnosis of a unicornuate or rudimentary uterus is the key to improving pregnancy outcomes. The high prepregnancy diagnosis rate may be due to improvements in examination methods in recent years, as well as the fact that gynaecologists have paid more attention to patients who are infertile or have adverse pregnancy outcomes. At present, clinical diagnosis is mainly based on ultrasound, hysterosalpingography, and hysteroscopy or laparoscopy. In addition, MRI, three-dimensional (3D) ultrasonography and four-dimensional hysterosalpingo-contrast sonography (4D-HyCoSy) are gradually being used for the diagnosis and further clarification of the type of uterine abnormality, and they can dramatically increase the accuracy of diagnosis [4, 16–21].
Previous studies have reported that the presence of a unicornuate uterus is associated with adverse pregnancy outcomes [2]. Our study revealed that compared with singleton pregnancies, twin pregnancies in women with a unicornuate uterus were associated with adverse pregnancy outcomes, such as PROM (38.1%, 8/21), PTDs (85.7%, 18/21), neonatal intensive care unit (64.3%, 27/42) admission, and lower birth weight. Previous studies have also revealed that twin pregnancies in women with a unicornuate uterine anomaly are associated with increased risks of preterm delivery, perinatal mortality, and low birth weight [22]. Thus, our findings agree with those of previously published studies. On the other hand, Ouyang et al. reported that the selective reduction of twins to a singleton may yield better outcomes in patients with unicornuate uterine anomalies who are undergoing IVF-ET [22]. Therefore, twin pregnancies should be prevented in women with a unicornuate uterus as much as possible, and attention should be given to prepregnancy examinations in reproductive-aged women. If a unicornuate uterus is diagnosed prepregnancy, comprehensive counselling about the high risk of twin pregnancy should be provided, including whether a single embryo transfer or selective reduction to a singleton should be performed, which may be considered to improve pregnancy outcomes in pregnant women with a unicornuate uterus who become pregnant with twins after assisted reproduction technology [23]. The incidence of adverse pregnancy outcomes in twin-pregnant women with a unicornuate uterus is greater than that in twin-pregnant women with a normal uterus or singleton pregnant women with a unicornuate uterus, which may be related to the fact that the unicornuate uterus has only one uterine artery and some small contralateral arteries supplying blood to the uterus, which reduces muscle perfusion, and causes a lower uterine muscle mass, an abnormal uterine blood flow, an abnormal shape of the uterine cavity, and a reduced uterine cavity volume, which are associated with a significantly greater risk for adverse pregnancy outcomes in women with twin pregnancies [4, 5].
Twin pregnancy in women with a unicornuate uterus is rare and poses considerable risks to mothers and foetuses. In our study, patients with a unicornuate uterus diagnosed before conception or during early pregnancy received management for high-risk pregnancies and strengthened supervision and had an increased frequency of prenatal check-ups to decrease the risk of pregnancy complications and adverse pregnancy outcomes. Because a unicornuate uterus may be associated with renal anomalies [3], it is recommended that patients with a unicornuate uterus undergo routine ultrasound screening of the urinary system and be screened for developmental anomalies of other organs. Moreover, ultrasound screening of the foetal system should be performed during pregnancy to detect foetal developmental abnormalities in time.
The caesarean section rate for twin-pregnant women with a unicornuate uterus is as high as 90.5% (19/21), but malpresentation, ICP, and PROM constituted the main indications for caesarean section (12/21, 57.1%) in our study. Pregnancy in women with a uterine anomaly is not an absolute indication for caesarean section. However, owing to the morphological and structural abnormalities of a unicornuate uterus, incomplete development of the myometrium, and poor muscle perfusion, the symmetry and polarity of contractions are affected, which may lead to abnormal labour. Twins conceived through IVF-ET are important and patients mostly choose caesarean section to terminate the pregnancy, so the indications for a caesarean section to terminate pregnancy may be relaxed. Given that the pregnant uterus has abundant blood circulation, we usually do not perform corrective surgery in women with a rudimentary uterus without an endometrium during a caesarean section. In recent years, studies have shown that the vaginal delivery of eligible twin pregnancies is feasible [10, 24, 25]. In this study, there was one case of vaginal delivery with a favourable outcome for the mother and child, and no adverse pregnancy outcomes, such as uterine rupture or postpartum haemorrhage, occurred. This finding suggests that vaginal delivery in women with a unicornuate uterus is feasible; however, this is only one case, and the indications for vaginal delivery in twin-pregnant women with a unicornuate uterus need to be confirmed by more clinical studies.
In our study, we found that haemorrhage at delivery was greater in twin-pregnant women with a unicornuate uterine than in singleton pregnant women with a unicornuate uterus and twin-pregnant women with a normal uterus. Nevertheless, there was no statistically significant difference in the incidence of postpartum haemorrhage after the use of powerful drugs to promote uterine contraction and appropriate surgical management. The increased risk of postpartum haemorrhage in twin-pregnant women with a unicornuate uterus calls for enhanced uterine contractions, improved surgical skills, close monitoring of postpartum haemorrhage, and timely intervention measures.
Strengths and limitations
The strengths of our study are that previous studies on twin pregnancies in women with a unicornuate uterus were only case reports, and our study, with a larger number of patients, allowed for a more comprehensive analysis of the perinatal characteristics and possible adverse pregnancy outcomes of twin pregnancies in women with a unicornuate uterus. However, the main limitation of our study is that it was a retrospective single-centre study on twin pregnancies in women with a unicornuate uterus, and more prospective multicentre studies are needed for further confirmation.
Conclusion
Perinatal risk is greater in twin-pregnant women with a unicornuate uterus than in singleton pregnant women with a unicornuate uterus and twin-pregnant women with a normal uterus. For patients with a unicornuate uterus, if the diagnosis is made preconception, twin pregnancy should be considered before IVF-ET or the first trimester. If twin pregnancy is unavoidable, attention should be given to health care during pregnancy and the supervision of mothers and children in the perinatal period. The overall pregnancy and neonatal outcomes of twin pregnancies in women with a unicornuate uterus are favourable.
Acknowledgements
We are grateful to the doctors and staff who have been involved in this work.
Abbreviations
- IVF-ET
In vitro fertilization-embryo transfer
- FGR
Foetal growth restriction
- PTD
Preterm delivery
- ART
Assisted reproductive technology
- ESHRE
The European Society of Human Reproduction and Embryology
- ESGE
The European Society for Gynaecological Endoscopy
- DCDA
Dichorionic diamniotic
- MCDA
Monochorionic diamniotic
- NICU
The neonatal intensive care unit
- HDCP
Hypertensive disorder complicating pregnancy
- ICP
Intrahepatic cholestasis of pregnancy
- PPH
Postpartum hemorrhage
- IUD
Intra-uterine death
- DM
Diabetes mellitus
- GDM
Gestational diabetes mellitus
- PGDM
Pregestational diabetes mellitus
- LBW
Live birth weight
Author contributions
SW interpreted data and literature review and drafted the manuscript. HL participated in data collection and the analysis of cases. QH participated in the design of the study. HYY conceived the study, supervised the entire study, and revised the manuscript. All authors have read and approved the final manuscript.
Funding
This study was supported by the Natural Science Foundation of Sichuan (2022NSFSC0659).
Data availability
No datasets were generated or analysed during the current study.
Declarations
Conflict of interest
The authors declare no competing interests.
Ethical approval and informed consent
The study was approved by the ethics committee of West China Second University Hospital (No. 2023-272). The informed consent was obtained from all the participants.
Footnotes
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
No datasets were generated or analysed during the current study.