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Porcine aortic tissue was decellularized by subcritical dimethyl ether (DME) used as an alternative to the surfactant sodium dodecyl sulfate. The process included three steps. For the first step, lipids were extracted from the porcine aorta using subcritical DME at 23 °C with a DME pressure of 0.56 MPa. Next, DME was evaporated from the aorta under atmospheric pressure and temperature. The second step involved DNA fragmentation by DNase, which was primarily identical to the common method. For the third step, similar to the common method, DNA fragments were removed by washing with water and ethanol. After 3 days of DNase treatment, the amount of DNA remaining in the porcine aorta was 40 ng/dry-mg, which was lower than the standard value of 50 ng/mg-dry. Hematoxylin and eosin staining showed that most cell nuclei were removed from the aorta. These results demonstrate that subcritical DME eliminates the need to utilize surfactants.

Secondary postpartum hemorrhage (PPH) is defined as excessive vaginal blood loss occurring between 24 h and 6-12 weeks after birth. The incidence of secondary PPH varies from 0.2% to 3.0%, and the peak incidence ranges from 1 to 2 weeks postpartum. There is no clinical evidence regarding the cause of secondary PPH. Therefore, this study aimed to determine the predictive factors for secondary PPH in an Asian population.A case-control study was performed. The clinical data of 25 secondary PPH patients who had been admitted to our hospital between June 2012 and January 2019 were obtained for this study. Control patients (The median maternal age was 34 years (range, 24-42 years); 85 (68.0%) women were nulliparous, 31 (24.8%) used ART, and 116 (92.8%) had term deliveries. Immediate PPH (adjusted odds ratio [OR], 2.84; 95% confidence interval [CI], 1.04-7.75) and manual removal of the placenta (adjusted OR, 6.14; 95% CI, 1.21-31.1) were associated with secondary PPH.Increasing the awareness of the predictive factors for secondary PPH could play an important role in the recognition and treatment of postpartum morbidity.

Objective: To examine whether fetal transverse cerebellar diameter (TCD) to abdominal circumference (AC) ratio can predict small-for-gestational age suspected as a cause of maternal placental syndr...

Labor arrest is the most common indication for emergency cesarean section (ECS). Increased biparietal diameter (BPD) has been reported as a risk factor for ECS due to labor arrest in different countries, but it is unclear whether this relationship is relevant in Japan. Considering the difference in maternal physique according to race and ethnicity, we retrospectively evaluated the association between ECS due to labor arrest and BPD, measured by ultrasonography < 7 days before term deliveries in Japanese women. BPD is routinely measured in Japan for estimating fetal weight. Information was extracted from obstetric records at the National Hospital Organization Kofu National Hospital between January 2012 and November 2019. Patients with multiple pregnancies, instrumental (forceps or vacuum) delivery, elective cesarean sections, and ECS due to reasons other than labor arrest were excluded. Thus, 2,695 women were included (age, 31.3 ± 6.2 years; pre-pregnancy body mass index, 20.9 ± 3.2 kg/m2), and 1,319 (48.9%) were nulliparous. The incidence of ECS due to labor arrest was 2.4% (64/2,695). Multivariable analysis indicated that BPD was significantly associated with ECS due to labor arrest (adjusted odds ratio, 1.12; 95% confidence interval, 1.04-1.20). The optimal BPD cut-off value for predicting ECS due to labor arrest was 94 mm (area under the curve, 0.61; sensitivity, 53.1%; specificity, 65.1%). Despite the significant association with ECS, BPD is not useful to predict ECS due to labor arrest. Thus, mothers should be encouraged for attempting vaginal deliveries, even in the case of having babies with large fetal BPD.

BackgroundInterstitial lung disease (ILD) occasionally occurs in rheumatoid arthritis (RA) and confers a dismal prognosis. We previously reported that a single-nucleotide variant (SNV) ofMUC5Bwas associated with ILD in RA. However, the pathogenesis of ILD in Japanese patients with RA could not be explained solely by this SNV because its frequency is extremely low in the Japanese population. Here, we examined whether a different idiopathic pulmonary fibrosis susceptibility SNV might be associated with ILD in Japanese patients with RA.MethodsGenotyping of rs2609255 (G/T) inFAM13Awas conducted in 208 patients with RA with ILD and 420 without chronic lung disease using TaqMan assays.ResultsA significant association with usual interstitial pneumonia (UIP) in RA was detected for rs2609255 under the allele model (p=0.0092,Pc=0.0276, OR 1.53, 95% CI 1.12 to 2.11) and recessive model for the G allele (p=0.0003,Pc=0.0009, OR 2.63, 95% CI 1.59 to 4.32).FAM13Ars2609255 was significantly associated with UIP in male patients with RA (p=0.0043, OR 3.65, 95% CI 1.52 to 8.73) under the recessive model.ConclusionsThis study is the first to document an association of rs2609255 with ILD in Japanese patients with RA, implicating it in the pathogenesis of UIP, though studies on the function of rs2609255 are warranted.

Shoulder dystocia is defined as vaginal cephalic delivery that requires additional obstetric maneuvers to deliver the fetus after the head has been delivered and gentle traction has failed. A bigger difference between the transverse abdominal diameter (TAD) (abdominal circumference [AC]/π) and biparietal diameter (BPD) (TAD-BPD) has been reported as a risk factor for shoulder dystocia in different countries; however, it remains unclear if this relationship is relevant in Japan. This study aimed to clarify the association between TAD-BPD and shoulder dystocia after adjusting for potential confounding factors in a Japanese cohort. We retrospectively examined 1,866 Japanese women who delivered vaginally between 37+0 and 41+6 weeks of gestation at the University of Yamanashi Hospital between June 2012 and November 2018. The cutoff value of TAD-BPD associated with shoulder dystocia and the association between TAD-BPD and shoulder dystocia were evaluated. The mean maternal age was 32.5±5.3 years; the patients included 1,053 nulliparous women (57.5%), 915 male infants (49.0%), 154 women with gestational diabetes mellitus (GDM) (8.3%), and 5 infants with macrosomia (0.3%). The mean TAD-BPD was 9.03±4.7 mm. The overall incidence of shoulder dystocia was 2.4% (44/1866). The cutoff value to predict shoulder dystocia was 12.0 mm (sensitivity, 61.4%; specificity, 73.8%; likelihood ratio, 2.34; positive predictive value, 5.4%; negative predictive value, 98.8%). We then used a multivariable logistic regression analysis to examine the association between TAD-BPD and shoulder dystocia while controlling for the potential confounding factors. In multivariate analyses, TAD-BPD ≥12.0 mm (adjusted odds ratio [OR], 4.39; 95% confidence interval [CI], 2.35–8.18) and GDM (adjusted OR, 3.59; 95% CI, 1.71–7.52) were associated with shoulder dystocia. Although TAD-BPD appears to be a relevant risk factor for shoulder dystocia, sonographic fetal anthropometric measures do not appear to be useful in screening for shoulder dystocia due to a low positive predictive value.

Prolonged second stage of labor is a common abnormality of labor progression. Very little research exists regarding the relationship between prolonged second stage of labor and antepartum sonographic fetal head biometry parameters, especially fetal biparietal diameter (BPD). Fetal BPD assessment is essential for estimating fetal weight, and these measurements are readily available to Japanese obstetricians. We conducted a retrospective observational cohort study to evaluate the association between BPD fetal Z-score and prolonged second stage of labor in a Japanese cohort. Individual BPD data measured using a GE Voluson 730 expert ultrasound system (GE, Healthcare Japan, Tokyo, Japan) were converted to Z-scores for a particular gestational age. After excluding patients with multiple pregnancies and emergency or elective cesarean sections, a total of 2,711 (nulliparity, n = 1341) Japanese women who delivered at term were included. We analyzed the incidence of prolonged second stage of labor and the association between BPD Z-score measured

ObjectivesThis study aimed to identify intrauterine growth differences according to infertility treatment compared with spontaneous conception and to describe intrauterine growth trajectories.DesignRetrospective cohort study.SettingA single primary and tertiary medical centre in Japan.ParticipantsThis study included singleton pregnant women with prenatal check-ups and delivery at the University of Yamanashi Hospital between 1 July 2012 and 30 September 2017. Patients were divided into four groups: spontaneous conception, infertility treatment without assisted reproductive technology (ART), fresh-embryo transfer and frozen embryo transfer (FET).InterventionsDifferences in intrauterine growth according to the infertility treatment, including ART, and birth weight were evaluated. Multilevel analysis was employed to evaluate intrauterine growth trajectories stratified by the sex of the offspring.Primary outcome measureEstimated fetal weight (EFW) assessed by ultrasound examination.ResultsWe assessed data from 37 239 prenatal examination results from 2377 pregnant women (spontaneous conception, n=1764; infertility treatment without ART, n=171; fresh-embryo transfer, n=112; and FET, n=330) in the final analysis. Multilevel analysis was adjusted for gestation duration, gestation period, parity, hypertensive disorders of pregnancy, type of infertility treatment, maternal age, smoking status, placenta previa, thyroid disease, gestational diabetes mellitus and the interaction between each potential confounding factor and gestation duration. In male fetuses, the interaction between FET and gestational duration (estimate: 0.36; 95% CI: 0.06 to 0.67) significantly affected the EFW. Similarly, in female fetuses, FET (estimate: −69.85; 95% CI: −112.09 to −27.61) and the interaction between FET and gestation duration (estimate: 0.57; 95% CI: 0.28 to 0.87) significantly affected the EFW.ConclusionsThis study shows that FET affects intrauterine growth trajectory from the second trimester to term, particularly in female fetuses. Our findings require further prospective research to examine the effect of infertility treatment on fetal growth.

ObjectiveWe evaluated the association between the presence of predelivery uterine contractions and transient tachypnoea of the newborn (TTN) in women undergoing an elective caesarean section.DesignA retrospective cohort study.SettingNational Hospital Organization Kofu National Hospital, which is a community hospital, between January 2011 and May 2019.ParticipantsThe study included 464 women who underwent elective caesarean section. The exclusion criteria were missing data, twin pregnancy, neonatal asphyxia, general anaesthesia and elective caesarean section before term.Primary and secondary outcome measuresPatients were grouped according to the presence or absence of uterine contractions on a 40-min cardiotocogram (CTG) performed within 6 hours before caesarean delivery. We performed a multivariable logistic regression analysis to examine the association between predelivery uterine contractions and TTN.ResultsThe incidence of TTN was 9.9% (46/464), and 38.4% (178/464) of patients had no uterine contraction. The absence of uterine contractions was significantly associated with an increased risk of TTN (adjusted OR 2.04; 95% CI 1.09 to 3.82) after controlling for gestational diabetes mellitus, small for gestational age, male sex and caesarean section at 37 weeks.ConclusionsAccurate risk stratification using a CTG could assist in the management of infants who are at risk of developing TTN.

A 72-year-old female patient with relapsing polychondritis (RP) with auricular chondritis, arthritis, and tenosynovitis, was evaluated by ultrasonography (US). On US of the auricle, epidermis, derm...

A low-lying placenta is a well-known cause of a massive intrapartum haemorrhage. We aimed to evaluate whether neonatal birth weight deviation from the nationwide average could predict a massive haemorrhage during a delivery in the women with a low-lying placenta. This study included 40 women. The main outcomes were a massive haemorrhage and a neonatal birth weight deviation. We used a receiver operating characteristic curve analysis to determine the optimal birth weight deviation cut-off for predicting a massive haemorrhage. A multiple logistic regression model was used to identify the variables significantly associated with a massive haemorrhage. The best cut-off for predicting a massive haemorrhage was a birth weight deviation of +0.51 standard deviations (SDs) from the nationwide average. A birth weight deviation of ≥ +0.51 SDs was significantly associated with an increased massive haemorrhage risk. Impact statement What is already known on this subject? A low-lying placenta is a well-known cause of a massive intrapartum haemorrhage. Therefore, when managing pregnancies with a low-lying placenta, the possibility of severe perinatal bleeding should be considered, and it is desirable to determine reliable predictors of a haemorrhage. However, few studies have reported the predictive factors of a massive haemorrhage in patients with a low-lying placenta. What do the results of this study add? We demonstrated that a birth weight deviation from the nationwide average was significantly associated with a massive intrapartum haemorrhage in patients with a low-lying placenta. To our knowledge, this is the first study to clarify the association between a neonatal birth weight and a massive intrapartum haemorrhage incidence and to determine the optimal birth weight deviation cut-off for predicting a massive haemorrhage in patients with a low-lying placenta. What are the implications of these findings for clinical practice and/or further research? An accurate risk stratification using the foetal weight as a marker for a predicting massive intrapartum haemorrhage may help in the management of patients with a low-lying placenta. Studies with a larger sample size are required to confirm our findings.

We report a case of minimal deviation adenocarcinoma (MDA) of the uterine cervix showing varicolored cytopathologic features on Papanicolaou (Pap) smear, which may indicate features suggestive of lobular endocervical glandular hyperplasia (LEGH)-adenocarcinoma sequence. A 57-year-old woman presented with a profuse amount of watery vaginal discharge. Gynecological examination revealed a cervical mass with involvement of the right parametrium. Conventional Pap smear showed hypercellularity consisting of approximately 4 types of clusters as follows: (1) clusters showing a monolayered honeycomb sheet of endocervical cells with golden-yellow mucin and bland nuclei, (2) three-dimensional clusters showing varicolored mucin and irregular nuclear overlapping, (3) irregularly shaped clusters showing distorted chicken-wire-mesh appearance with noticeable protrusions of the nuclei and clear or faint varicolored cytoplasm, and (4) crowded clusters showing scarce mucin and nuclear atypia. The surgically resected uterus revealed LEGH-mimicking lesion with fused papillae and a cribriform pattern in the endocervix and many glands exhibiting gastric differentiation that invaded deeper areas of the stroma with a subtle stromal reaction. Compared with histologic findings, two types of clusters, the crowded cluster with scarce mucin and the cluster with distorted chicken-wire-mesh-type appearance, were considered as adenocarcinoma, and the latter was interpreted as a gastric-type adenocarcinoma. Three-dimensional varicolored type clusters showed atypical features, but insufficient atypical features compared with those of adenocarcinoma. Detection of clusters with varicolored mucin on conventional Pap smear may provide a clue for the early recognition of the malignant potential of LEGH on cytology. The chicken-wire-mesh type clusters may be a characteristic cytologic finding of MDA.

Vasa praevia, a condition where the umbilical cord runs through the foetal membranes over the internal cervical os, is rare, occurring in 1.5–4 of 10,000 pregnancies (Oyelese et al. 1999; Lee et al...

Objective To evaluate the risk of spilling cancer cells during total laparoscopic hysterectomy (TLH) using a uterine manipulator in early-stage endometrial cancer patients. Materials and methods We conducted a prospective study among women undergoing TLH for Clinical Stage IA endometrial cancer between March 2015 and November 2015. Peritoneal washings before the insertion of the uterine manipulator and after TLH were obtained. The two sets of washings were reviewed by a cytopathologist to determine the presence or absence of malignant cells in a blinded manner. Results Thirteen endometrial cancer patients (age 39–79 years, median: 62.2 years) were enrolled. The postoperative tumor grades were: G1: 11 (84.6%) and G2: 2 (15.4%). All patients underwent TLH and bilateral salpingo-oophorectomy. Pelvic/para-aortic lymph node dissection was not performed in all cases. Only one patient showed positive peritoneal cytology in the pre-TLH sample. There was high agreement (92.3%) between the two sets of washings in all patients. No patients received postoperative treatment. Conclusion We conclude that fallopian tubal cauterization is sufficient to provide protection from the dissemination of cancer cells into the peritoneal cavity at the time of TLH for endometrial cancers in early stages.

Objective Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized with joint destructions; environmental and genetic factors were thought to be involved in the etiology of RA. The production of anti-citrullinated peptide antibodies (ACPA) is specifically associated with RA. DRB1 is associated with the susceptibility of RA, especially ACPA-positive RA [ACPA(+)RA]. However, a few studies reported on the independent associations of DPB1 alleles with RA susceptibility. Thus, we investigated the independent association of DPB1 alleles with RA in Japanese populations. Methods Association analyses of DPB1 were conducted by logistic regression analysis in 1667 RA patients and 413 controls. Results In unconditioned analysis, DPB1*04:02 was nominally associated with the susceptibility of ACPA(+)RA (P = 0.0021, corrected P (Pc) = 0.0275, odds ratio [OR] 1.52, 95% confidence interval [CI] 1.16–1.99). A significant association of DPB1*02:01 with the susceptibility of ACPA(+)RA was observed, when conditioned on DRB1 (Padjusted = 0.0003, Pcadjusted = 0.0040, ORadjusted 1.47, 95%CI 1.19–1.81). DPB1*05:01 was tended to be associated with the protection against ACPA(+)RA, when conditioned on DRB1 (Padjusted = 0.0091, Pcadjusted = 0.1184, ORadjusted 0.78, 95%CI 0.65–0.94). When conditioned on DRB1, the association of DPB1*04:02 with ACPA(+)RA was disappeared. No association of DPB1 alleles with ACPA-negative RA was detected. Conclusion The independent association of DPB1*02:01 with Japanese ACPA(+)RA was identified.

Aim There is no consensus opinion regarding a possible relation between low 50-g glucose challenge test (GCT) results and small-for-gestational-age infants (SGA). This study aimed to clarify the relation between low 50-g GCT results and SGA, after adjusting for potential confounding factors, using a large clinical dataset. Material and Methods Our retrospective cohort study evaluated the obstetric records of women who delivered at Kofu Municipal Hospital (Japan) between January 2011 and December 2013. The exclusion criteria were gestational diabetes mellitus, diabetes in pregnancy, and GCT results of ≥140 mg/dL. Based on these criteria, we included 1603 women who had undergone a GCT between 24 and 28 weeks of gestation, and divided the subjects into a low-GCT group (≤90 mg/dL) and a non-low-GCT group (91–139 mg/dL). The χ2-test and multivariate logistic regression analysis were used to investigate the association between low GCT results and SGA. Results The mean subject age was 30.4 ± 5.4 years, with 45.1% nulliparity (n = 723) and 1538 (96.0%) term deliveries. The incidence of SGA was 10.7% (172/1603), and 17.9% (287/1603) of the women had low GCT results. Low GCT results were significantly associated with an increased risk of SGA (odds ratio, 1.66; 95% confidence interval, 1.14–2.42), after controlling for maternal age, pre-pregnancy maternal weight, maternal weight gain during pregnancy, and pregnancy-induced hypertension. Conclusion It appears that there is a significant association between low GCT results and SGA. However, further studies are needed to explore the detailed mechanisms of this association.

Key Clinical Message Spinal anesthesia is regularly performed worldwide and is an integral part of the modern day anesthesia practice. Although unexpected cardiac arrests during this procedure are very rare, medical professionals should be aware of the potential for this complication. In making the decision to use spinal anesthesia, judicious patient selection, adequate preventive measures, and strict monitoring are important.

To assess whether the high soluble fms-like tyrosine kinase-1 (sFlt-1) to placental growth factor (PlGF) ratio is associated with adverse outcomes (e.g., HELLP syndrome [hemolysis, elevated liver enzymes, and low platelets], severe hypertension uncontrolled by medication, non-reassuring fetal status, placental abruption, pulmonary edema, growth arrest, maternal death, or fetal death) and a shorter duration to delivery in early-onset fetal growth restriction (FGR).Thirty-four women with FGR diagnosed at34.0 weeks were recruited. Serum angiogenic marker levels were estimated within 6 hours of a diagnosis of FGR. A receiver operating characteristic curve was used to determine the threshold of the sFlt-1/PlGF ratio to predict adverse outcomes. We used multivariable logistic regression analysis to examine the association between the sFlt-1/PlGF ratio and adverse outcomes. Finally, we used Kaplan-Meier analysis and the log-rank test to assess the probability of delay in delivery.Women who developed adverse outcomes within a week had a significantly higher sFlt-1/PlGF ratio than did those who did not develop complications. A cutoff value of 86.2 for the sFlt-1/PlGF ratio predicted adverse outcomes, with a sensitivity and specificity of 77.8% and 80.0%, respectively. Moreover, 58.4% of women with an sFlt-1/PlGF ratio ≥86.2 versus 9.1% of those with an sFlt-1/PlGF ratio86.2 delivered within a week of presentation (p 0.001). In multivariate analyses, an sFlt-1/PlGF ratio ≥86.2 (adjusted odds ratio 9.52; 95% confidence interval, 1.25-72.8) was associated with adverse maternal and neonatal outcomes.A high sFlt-1/PlGF ratio was associated with adverse outcomes and a shorter duration to delivery in early-onset FGR.

A two-step process consisting of depolymerization and catalytic cracking without hydrogen addition was carried out to produce phenols from lignin. In the first step, lignin was depolymerized using a silica-alumina catalyst in a water/1-butanol solution at 623 K for 2 h. After the reaction, lignin-derived slurry liquid was obtained in 67 C-mol% yield. From the model studies, it was considered that lignin was mainly depolymerized via hydrolysis of aryl ether bonds between lignin units. For the second step, the catalytic reaction of the 1-butanol phase of the slurry liquid was carried out over an iron oxide catalyst using a high pressure fixed-bed flow reactor at 673 K. The catalytic reaction under high pressure steam conditions was effective for the suppression of the formation of solid products. In addition, the recovery fraction of phenols increased as the F H 2 O / F value (the flow rate ratio of steam to the slurry liquid) increased, resulting in 17% of phenols at F H 2 O / F = 5 for 2–4 h. From the model studies and our previous results, catechol and methoxyphenol in the slurry liquid were considered to be converted into phenols, cresols and other alkyl phenols over the iron oxide catalyst.

Supplemental Digital Content is available in the text, Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by joint destructions and human leukocyte antigen (HLA)-DRB1 is an important genetic risk factor for RA and influences the phenotype of RA. The clinical features of elder age onset RA (EORA) were known to be different from those of younger age onset RA (YORA). Previous studies reported the different association pattern of DRB1 alleles with YORA or EORA. The associations of DRB1 genotype with these RA subsets remained almost unknown. We investigated the genotype association of DRB1 with YORA or EORA in Japanese populations. HLA genotyping was performed in Japanese RA patients and the association of allele or genotype carrier frequencies were analyzed. The genotype frequency of DRB1∗04:05/DRB1∗04:06 (P = .0204, OR 7.69, 95%CI 1.39–42.72), DRB1∗04:05/DRB1∗12:01 (P = .0050, OR 5.53, 95%CI 1.71–17.88), and DRB1∗04:05/DRB1∗15:01 (P = .0124, OR 3.34, 95%CI 1.39–8.02) in YORA was higher than EORA. However, the frequencies of DRB1∗01:01/DRB1∗04:05 in YORA was tended to be lower than EORA (P = .0784, OR 0.14, 95%CI 0.01–2.42). The gene dosage effect of the shared epitope alleles was detected in EORA, but not in YORA. Trans-complementing DQ heterodimer molecules, formed by DQA1 and DQB1 of the haplotypes with and without shared epitope alleles, might explain the higher genotype frequencies of “shared epitope /not shared epitope”. Linear regression analyses showed the primary role of DQB1∗04:01 allele for the age at onset of RA. This is the first report for the associations of DRB1 genotype with YORA or EORA in the Japanese population and the differential distribution of the genotypes was noted between these RA subsets. The involvement of DQ molecules for the age at onset of RA was suggested.

Production of phenols from lignin was investigated using a new conversion process consisting of two reaction steps. In the first step, depolymerization of lignin was carried out in an autoclave reactor using a silica-alumina catalyst in a water/1-butanol solution. The yield of lignin-derived liquid product reached 85–88 C-mol% under the appropriate reaction conditions. In the second step, catalytic cracking of the liquid products from the first step was carried out using a fixed‐bed flow reactor over an iron oxide catalyst. With this method, total recovered fraction of phenols and the conversion of methoxy phenol reached 6.6–8.6% and 92–94%, respectively.

Variable-weight optical orthogonal code (OOC) was introduced by Yang for multimedia optical CDMA systems with multiple quality of service (QoS) requirements. In this paper, the upper bound on the size of variable-weight OOCs is improved, a cyclic t-(v, W, λ, Q) packing is introduced to construct a variable-weight OOC, an upper bound for the number of blocks of t-(v, W, λ, Q) packings is obtained, and an equivalence between optimal cyclic packing and optimal variable-weight optical orthogonal code is established. Recursive constructions for optimal 2-CP(W, 1, Q;v)s are also presented. By using skew starters and these constructions, infinite classes of optimal (v, W, 1, {1/2, 1/2})-OOCs are obtained for W = {3, 4}, and {4, 5}.

ObjectivePulmonary oedema is recognised as a severe side effect of ritodrine hydrochloride. Recently, the number of twin pregnancies has been increasing. Few studies have reported the association between total dose of ritodrine hydrochloride prior to delivery and pulmonary oedema in twin pregnancy. We aimed to examine this association and determine the optimal cut-off threshold of total ritodrine hydrochloride dose to predict the incidence of pulmonary oedema in twin pregnancy based on obstetric records.DesignRetrospective cohort study.SettingYamanashi Prefectural Central Hospital, Japan.ParticipantsTwo hundred and twenty-six women with twin pregnancy who delivered at Yamanashi Prefectural Central Hospital between September 2009 and November 2016.MethodsThe obstetric records of the participants were analysed. We defined 1 unit of ritodrine hydrochloride as 72 mg per 24 hours continuous transfusion at 50 µg/min to calculate the dose of ritodrine used for tocolysis.Outcome measuresMultivariable logistic regression analysis was performed to examine the association between total dose of ritodrine hydrochloride used for threatened preterm labour and pulmonary oedema, while controlling for potential confounding factors. Then, a receiver–operating characteristic curve was used to determine the optimal cut-off of total ritodrine dose to predict pulmonary oedema incidence.ResultsMean maternal age was 32 (range, 18–46) years; 143 participants were nulliparous (63.3%), 109 had (48.2%) term deliveries and 194 (85.8%) had caesarean deliveries. The overall incidence of pulmonary oedema was 13.7% (31/226). Multivariable analysis showed that the total dose of ritodrine was significantly associated with pulmonary oedema (adjusted OR 1.02; 95% CI 1.004 to 1.03). The best cut-off point to predict the incidence of pulmonary oedema was 26 units (1872 mg) (sensitivity, 61.3%; specificity, 87.8%).ConclusionOur results suggest that consideration of the total dose of ritodrine hydrochloride is helpful in the management of patients with threatened preterm labour in twin pregnancy.