Does maternal oxygen administration during non-reassuring fetal status affect the umbilical artery gas measures and neonatal outcomes?

PURPOSE: To clarify whether maternal oxygen administration during vaginal delivery improves umbilical artery (UA) gas measurements and neonatal outcomes. METHODS: Singleton pregnancies requiring operative vaginal delivery or emergency cesarean section (CS) due to non-reassuring fetal status (NRFS) during vaginal delivery at our hospital from 2018 to 2021 were retrospectively investigated. Intrapartum fetal wellbeing was evaluated based on the 5-tier fetal heart rate (FHR) pattern which is a delivery management method widely used in Japan. Operative vaginal deliveries or emergency CS was performed under integrated judgment in NRFS. Patients were divided into the oxygen group to whom oxygen (10 L/min) was supplied by a facemask and the room air group. The UA gas measurements and neonatal outcomes were compared. The oxygen administration was classified by conditions before and after the coronavirus disease 2019 pandemic. As a secondary evaluation, stratification of FHR pattern levels and factors associated with UA pH < 7.15 were examined. RESULTS: A total of 250 patients required obstetric surgical delivery due to NRFS, including 140 (56%) and 110 (44%) in the oxygen and room air groups, respectively. No differences in maternal background factors were found between both groups, except for maternal age. UA gas measurements and neonatal outcomes also showed no significant differences. No significant factors were extracted in the multivariate analysis for UA pH < 7.15. CONCLUSIONS: Trans-maternal oxygen administration for intrapartum NRFS did not affect neonatal cord blood gasses or neonatal outcomes. Thus, routine oxygen administration for intrapartum NRFS may not always be necessary.

The role of first-trimester ultrasound screening for women with positive noninvasive prenatal testing results.

AIM: This study aimed to assess the utility of ultrasound screening for pregnancies with positive noninvasive prenatal testing results for trisomy 21, trisomy 18, and trisomy 13. METHODS: We performed a retrospective analysis of positive noninvasive prenatal testing results and first-trimester ultrasound screening at our department between 2013 and 2019. Invasive genetic testing was performed if the patient had positive noninvasive prenatal testing results. Fetal ultrasound and cytogenetic data were collected. Noninvasive prenatal testing was performed in the women for advanced maternal age, nuchal translucency thickness, or history of abnormality in the previous child or relative. RESULTS: Forty-one pregnant women had positive noninvasive prenatal testing results for trisomy 21, trisomy 18, and trisomy 13. Twenty-three women had positive results for trisomy 21, 13 had positive results for trisomy 18, and 5 had positive results for trisomy 13 at 11 to 14 weeks of gestation. The positive predictive value of noninvasive prenatal testing was 100% for trisomy 21, 84.6% for trisomy 18, and 100% for trisomy 13. The positive predictive value of positive noninvasive prenatal testing results and fetal morphological abnormalities was 100% for trisomy 21, trisomy 18, and trisomy 13. CONCLUSION: Combining an ultrasound examination with noninvasive prenatal testing resulted in a higher positive predictive value for trisomy 18. Normal ultrasound examination results can help alleviate stress caused by false-positive noninvasive prenatal testing results. In contrast, the positive predictive value and negative predictive value for trisomy 21 were not altered by adding an ultrasound examination to noninvasive prenatal testing.

Impact of first trimester determination of abnormal cord insertion on twin-to-twin transfusion syndrome and other adverse outcomes in monochorionic diamniotic twins: A retrospective cohort study.

OBJECTIVE: To assess the influence of abnormal cord insertion (CI) detected by first trimester ultrasonography on the development of twin-to-twin transfusion syndrome (TTTS) in monochorionic diamniotic (MCDA) twins. METHOD: In this retrospective cohort study, consecutive patients with MCDA twins who underwent fetal ultrasound screening in the first trimester between January 2011 and January 2017 were enrolled. The CI sites were evaluated between 11 + 0 and 13 + 6 weeks' gestation. All twin pairs were assigned to the abnormal CI group (twin pair with velamentous cord insertion (VCI) and/or marginal cord insertion (MCI) in one or both twins) or the normal CI group (twin pair with both normal CI). The relationships of adverse outcomes in two groups were analyzed. RESULTS: A total of 109 MCDA twin pairs were examined; 15 cases were classified into the abnormal CI group and 94 cases into the normal CI group. The incidence of TTTS was significantly higher in the abnormal than in the normal CI group (26.7% vs 7.45%, P = .04). In patients who developed TTTS, all donors had VCI. CONCLUSION: Ultrasound evaluation of abnormal CI at 11 + 0 to 13 + 6 weeks' gestation in MCDA twins is valuable in the assessment of the risk for TTTS.

Differences in perinatal outcomes according to forming period of single umbilical cord in singleton pregnancy.

OBJECTIVES: The aim of this study was to establish the frequency and associations of single umbilical artery (SUA) diagnosed until the first vs second or third trimester. METHODS: A retrospective cohort study was conducted on singleton pregnancies at a tertiary perinatal center. All women underwent both the first and second trimester scans in which the number of arteries in the umbilical cord was routinely documented. SUA was classified as aplastic type when the diagnosis was made in the first trimester and as occlusion type when diagnosed in the second or third trimester. Adverse perinatal outcome was calculated as occurrence of fetal death, birthweight centile < 10th , or Apgar score at 5 minutes < 7. RESULTS: A total of 8675 women underwent ultrasound examinations during the study period. Of the 32 SUA cases, 17 (0.2%) were of the aplastic type and 15 (0.2%) of the occlusion type. Congenital anomalies were more in aplastic than in occlusive SUA (58.8% vs 20%, .043). The occlusive SUA had higher postnatal coiling index (0.3 vs 0.2, .034) and diagnosis of hypercoiled cord (46.7% vs 5.9%, .013) than the aplastic type. CONCLUSIONS: The different gestational age at diagnosis and coiling characteristics suggest two types of SUA, namely, aplastic and occlusion types, which are associated with differences in perinatal outcomes.

Cross-cultural, population-based study on adolescent body image and eating distress in Japan and Finland.

This cross-sectional population-based survey compares the prevalence of self-reported body image and eating distress symptoms among adolescents in Japan and Finland, and associations between emotional/behavioral problems, body image and eating distress from a cross-cultural perspective. The study included 1,840 Japanese and 1,135 Finnish 8th grade students. The self-reported questionnaire included the Body Image and Eating Distress Scale and Strengths and Difficulties Questionnaire (SDQ). The female adolescents from both Finland and Japan reported much greater dissatisfaction with, and concern about, their bodies than the males and Japanese females expressed even higher distress than Finnish females. High levels of body image and eating distress were associated with psychiatric problems measured with the SDQ. There was a significant three-way interaction effect of body image and eating distress, gender and country with SDQ peer problems and prosocial behavior.

Association between bullying behavior, perceived school safety, and self-cutting: a Japanese population-based school survey.

BACKGROUND: No previous population-based studies have examined associations between self-cutting, perceived school safety, and bullying behavior among East Asian adolescents. METHOD: We examined whether bullying, victimization, and perceived school safety were associated with self-cutting by getting 1865 students with a mean age of 13.9 years (standard deviation 0.2 years) to complete questions on these variables. Psychiatric problems were assessed with the Strengths and Difficulties Questionnaire. RESULTS: About 5.6% of males and 11.9% females had practiced self-cutting and when we controlled these results for psychiatric symptoms, self-cutting was associated with being both a bully and a victim among males and females. In addition, self-cutting was independently associated with perceived school safety among females. Those who felt unsafe at school and were victimized were much more likely to engage in self-cutting. CONCLUSIONS: Self-cutting among Japanese adolescents was linked with bullying behavior and feeling unsafe at school. Secure school environments and school-based antibullying programs could help to prevent adolescent self-injurious behavior.

Comparison of perinatal outcomes between long-term and short-term use of tocolytic agent: a historical cohort study in a single perinatal hospital.

AIM: The aim of this study was to evaluate the effect of long-term use of tocolytic agents to prevent preterm delivery and improve perinatal outcome. METHODS: A historical cohort study was performed in a single perinatal center. The maternal characteristics, frequency of preterm labor and prescribed dose of tocolytic agents were compared before and after changing the management protocol for threatened premature delivery. RESULTS: A total of 1548 deliveries were carried out before changing the protocol for the use of tocolytic agents for threatened premature delivery and 1444 deliveries afterwards. There was no significant difference in the maternal characteristics before and after the revision except for maternal age. The total number of ritodrine hydrochloride ampules used was reduced from 4654 to 514, and the total vials of magnesium sulfate used were reduced from 1574 to 193, but perinatal outcomes, such as rate of preterm birth, neonatal weight, and rate of NICU hospitalization were not different between the groups. CONCLUSION: There was no significant change in the frequency of preterm delivery before and after changing of the protocol for threatened premature delivery. Because a decrease in the given dose of tocolytic agents did not affect the timing of delivery and neonatal outcomes, long-term tocolysis in patients with threatened premature delivery should be restricted to prevent maternal and fetal adverse side-effects.

[Development of the unexpected reality scale for childcare training].

This study aimed to develop a scale for unexpected reality for childcare training (Study 1) and examine the change and influence it exerts on the efficacy of preschool teachers (Study 2). In Study 1, the sample consisted of 571 university and junior college students enrolled in a childcare course. After exploratory factor analysis, four factors were extracted: "actual feelings for childcare as a field of study," "difficulties faced during involvement with children," "negative aspects of the childcare worker," and "severity of work." The study's scale was shown to be internally consistent and valid. In Study 2, the sample consisted of 122 junior college students enrolled in a childcare course. The results showed that the high-scoring groups of each unexpected reality subscales experienced less unexpected reality in the subsequent training session. Moreover, the results of multiple regression showed that preschool teacher efficacy was predicted positively by "actual feelings for childcare as a field of study" and negatively by "difficulties faced during involvement with children." Thus, we suggest that for effective pre- and post-guidance of childcare training, unexpected realities should be considered.

Repeated Measurement of Crown-Rump Length at 9 and 11-13 Weeks' Gestation: Association with Adverse Pregnancy Outcome.

AIMS: To clarify whether ultrasonographic measurements of crown-rump length (CRL) at 11-13 weeks - based on the number of gestational days determined using the CRL at 9 weeks - can predict fetal prognosis. METHODS: A prospective cohort study was conducted to evaluate the association between fetal growth in the first trimester and fetal prognosis. Fetal growth in the first trimester was evaluated measuring CRLs at 11-13 weeks determined using the CRL at 9 weeks. The subjects were divided into short CRL (s-CRL) and normal CRL (n-CRL). The prognoses were compared between the two groups. RESULTS: A total of 126 patients in the s-CRL group and 1,130 patients in the n-CRL group were enrolled. Abortion occurred in 7.1% of s-CRL and 0.9% of n-CRL subjects (p < 0.001). Among the patients with chromosomal abnormalities, the incidence of trisomy 18 was significantly greater in s-CRL (4.8 vs. 0.1%, p < 0.001). Without abortion, placental weight, frequency of small for gestational age (SGA) and birth weight in s-CRL were significantly higher than those in the n-CRL group (12.8 vs. 3.6%, p < 0.001). CONCLUSIONS: Measuring CRL at 9 weeks is useful for determining gestational days prior to measuring CRL at 11-13 weeks. After reconfirming the gestational age at 9 weeks, measuring CRL at 11-13 weeks is useful for predicting the incidence of trisomy 18 as well as SGA later in pregnancy.

Is maternal anemia associated with small placental volume in the first trimester?

AIM: To clarify whether maternal anemia could reduce placental volume in the early gestation. METHODS: A prospective cross-sectional study was conducted. Consecutive women who visited at 11-13 + 6 weeks' gestation were enrolled. Subjects were divided into two groups by maternal hemoglobin concentration. Cases with maternal anemia were defined as a hemoglobin level less than 11 g/dl on a blood test (cases), and the others were defined as controls. An ultrasound examination was performed to measure the placental volume and the uterine arterial blood flow. The three-dimensional volume of the placenta using virtual organ computer-aided analysis (VOCAL) technique was acquired by transabdominal ultrasonography. Placental volumes were compared in women with and without anemia. RESULTS: 31 cases and 486 controls were analyzed. Maternal characteristics were not different between two groups except anemia. Placental volumes were 63.6 ± 22.2 and 60.9 ± 22.8 cm(3) (ns), uterine arterial RIs were 0.7 ± 0.1 and 0.8 ± 0.1 (ns), and PIs were 1.7 ± 0.5 and 1.8 ± 0.6 (ns) in cases and controls, respectively. CONCLUSIONS: Maternal anemia was not associated with reduced placental volume and uterine arterial Doppler wave form at 11-13 weeks' gestation.

Impacts of demographic factors and the COVID-19 pandemic on job stress in Japanese childcare workers.

BACKGROUND: Japan has a shortage of childcare personnel, and the high levels of stress causing turnover in childcare workers must be urgently resolved. However, there is a lack of knowledge regarding the characteristics and influencing factors of job stress in Japanese childcare workers. OBJECTIVE: This study aimed to evaluate the job stress of childcare workers and explore the influence of demographic factors and the COVID-19 pandemic on such stress. METHODS: The data were collected through an Internet survey from 2,472 respondents. A 23-item version of the Brief Job Stress Questionnaire was used to measure occupational stress in childcare workers. The instrument is recommended in the stress-check program implemented as a mental health measure in workplaces in Japan. RESULTS: The percentage of childcare workers with high stress exceeded that of general workers. Multiple regression analyses showed that the only factor affecting all job stressors and social support was the fear of contracting COVID-19. Job stressors and the COVID-19 pandemic had a significant large effect on stress responses. Additionally, being married and having children moderated childcare workers' stress. CONCLUSIONS: This study provided basic data regarding job stress in Japanese childcare workers and compared them with those of other professionals. In the future, it will be necessary to clarify how stress is related to turnover intention and turnover in Japanese childcare workers to promote their career continuity.

Antibacterial toner exhibits bactericidal effect against Cutibacterium acnes via keratin and sebum plug penetration.

Cutibacterium acnes is an opportunistic pathogen recognized as a contributing factor to acne vulgaris. The accumulation of keratin and sebum plugs in hair follicles facilitates C. acnes proliferation, leading to inflammatory acne. Although numerous antimicrobial cosmetic products for acne-prone skin are available, their efficacy is commonly evaluated against planktonic cells of C. acnes. Limited research has assessed the antimicrobial effects on microorganisms within keratin and sebum plugs. This study investigates whether an antibacterial toner can penetrate keratin and sebum plugs, exhibiting bactericidal effects against C. acnes. Scanning electron microscopy and next-generation sequencing analysis of the keratin and sebum plug suggest that C. acnes proliferate within the plug, predominantly in a biofilm-like morphology. To clarify the potential bactericidal effect of the antibacterial toner against C. acnes inside keratin and sebum plugs, we immersed the plugs in the toner, stained them with LIVE/DEAD BacLight Bacterial Viability Kit to visualize microorganism viability, and observed them using confocal laser scanning microscopy. Results indicate that most microorganisms in the plugs were killed by the antibacterial toner. To quantitatively evaluate the bactericidal efficacy of the toner against C. acnes within keratin and sebum, we immersed an artificial plug with inoculated C. acnes type strain and an isolate collected from acne-prone skin into the toner and obtained viable cell counts. The number of the type strain and the isolate inside the artificial plug decreased by over 2.2 log and 1.2 log, respectively, showing that the antibacterial toner exhibits bactericidal effects against C. acnes via keratin and sebum plug penetration.

Heparinoid enhances the efficacy of a bactericidal agent by preventing Cutibacterium acnes biofilm formation via quorum sensing inhibition.

Cutibacterium acnes is an opportunistic pathogen in acne vulgaris. C. acnes produces autoinducer-2 (AI-2）, a signaling molecule used for communication known as quorum sensing (QS）. In C. acnes, QS reportedly upregulates biofilm formation leading to resistance against bactericidal agents. In this study, we analyzed how heparinoid affected QS and biofilm formation of the opportunistic pathogen C. acnes. We also verified whether heparinoid would suppress biofilm formation and enhance the efficacy of the bactericidal agent 4-isopropyl-3-methylphenol (IPMP) against C. acnes biofilms. We ran an AI-2 bioassay using Vibrio harveyi ATCC BBA-1121. Heparinoid exhibited inhibitory activity against AI-2 at concentrations of 0.003-0.005%, suggesting an AI-2 analog-derived or C. acnes culture supernatant-derived inhibition of the AI-2 activity. To evaluate how heparinoid suppresses biofilm formation in C. acnes, we completed a biofilm assay in 96-well plates. We also evaluated the bactericidal activity of IPMP against the C. acnes biofilm prepared with or without heparinoid. Heparinoid inhibited C. acnes biofilm formation and IPMP bactericidal efficacy increased upon heparinoid-mediated suppression of biofilm formation. In this study, we clarified that heparinoid inhibits the AI-2-mediated QS of C. acnes, thereby suppressing biofilm formation and increasing IPMP bactericidal efficacy, potentially suppressing acne vulgaris.

The volume of the chorion villosum is associated with the location of the umbilical cord in the first trimester.

AIMS: To clarify whether villous placental volumes in cases with low cord insertion (CI) are smaller than those with normal cord insertion. METHODS: A prospective cohort study was conducted to evaluate the association between location of umbilical CI and placental volume at 11 to 13 weeks' gestation. An ultrasound examination was performed to measure the crown-rump length, the distance between the histological internal cervical os and the CI site, the placental volume, and the uterine arterial blood flow. To standardize the distribution of the ultrasonographic measurements, we transformed data by crown-rump length-weighted linear regression. RESULTS: Six hundred fifty-nine subjects were analyzed. Scatter plots showed a slightly positive correlation between the z-scores of the distance from the CI site to the internal cervical os and villous placental volume (r = 0.102, p = 0.009) and a negative correlation between the z-scores of the villous placental volume and the uterine arterial pulsatility index (r = -0.165, p < 0.001) as well as the uterine arterial resistance index (r = -0.187, p < 0.001). CONCLUSION: The placental volume was likely to be smaller in cases with CI located in the lower uterine segment.

Relationship between the umbilical cord coiling index and the umbilical blood flow at 11-13 weeks of gestation.

OBJECTIVES: The aim of this study was to clarify the effects of umbilical cord coiling on the umbilical blood flow at 11-13 weeks of gestation. METHODS: A cross-sectional study was conducted among consecutive pregnant females at 11-13 weeks of gestation. Transabdominal ultrasound examinations were performed to obtain the umbilical coiling index (CI), the maximum umbilical arterial peak velocity at the free loop, the venous velocities at the free loop and the umbilical ring, and the umbilical arterial and venous flow volumes. After every measurement was standardized according to the crown-rump length (CRL), correlations between the CI and these measurements were analyzed. RESULTS: A total of 364 subjects were enrolled. The CI significantly decreased in association with advancing gestation. There were significant correlations between the CRLs and the umbilical arterial peak velocities, the venous velocities at the free loop and the umbilical ring, and the umbilical arterial and venous flow volumes. The z-scores of the umbilical arterial and venous velocimetries exhibited no significant correlations with the CI. The umbilical arterial and venous flow volumes were also not found to correlate with the CI. CONCLUSIONS: The CI does not affect either the umbilical arterial or venous blood flow at 11-13 weeks of gestation.

Distribution of nuchal translucency thickness in Japanese fetuses.

AIM: To establish reference values for the nuchal translucency (NT) thickness in Japanese fetuses. MATERIAL AND METHODS: Ultrasonographic measurements of the crown-rump length (CRL) and NT were performed from 11 to 13 + 6 weeks of gestation in consecutive Japanese fetuses examined during prenatal visits between February 2011 and January 2012. The median, 5th and 95th percentiles of the NT thickness with 5 mm intervals of the CRL were confirmed. RESULTS: A total of 970 cases were enrolled in the study. The median NT thickness for a CRL between 45 and 80 mm ranged from 1.2 mm to 1.9 mm, and the 95th percentile of these values ranged from 2.1 mm to 3.2 mm, respectively. CONCLUSION: The reference values for the NT thickness in Japanese fetuses were determined. These values should be useful for fetal biometry, morphological assessment and first trimester screening for chromosomal abnormalities in Japan.

A case report of umbilical ring constriction with application of amnioinfusion.

This is a case report of a pregnant 38-year-old primigravida woman. Due to severe fetal growth restriction and oligohydramnios, she was referred to our tertiary perinatal center at 24 weeks' gestation. To rule out chromosomal abnormalities and facilitate ultrasound evaluation of fetal morphology, we performed amniocentesis and subsequent amnioinfusion. Thereafter, a precise ultrasound examination revealed no obvious fetal morphological abnormalities except for a hyper-coiled cord and marginal placenta previa. During expectant management, the amount of amniotic fluid was maintained at 20-26 mm for a few days; however, the pregnancy resulted in intrauterine fetal death after 26 weeks + 5 days of gestation. The stillborn infant weighed 530 g (-3.3 SD) and had no obvious external abnormalities apart from umbilical ring constriction. Although a postmortem autopsy was not performed, it is suspected that the fetal growth restriction and the intrauterine fetal death were associated with the hyper-coiled cord and the umbilical ring constriction. It is thought that umbilical ring constriction might therefore be an irreversible fatal condition in cases with a hyper-coiled cord.

Analysis of the predictable variables for placenta accreta without placenta previa.

OBJECTIVES: To clarify the predictive variables for adherence of the placenta (AP) in cases without placenta previa. METHODS: A prospective cohort study was conducted between 2008 and 2010. Patients without placenta previa who delivered singleton babies after 36 weeks' gestation were enrolled. The maternal and ultrasonographic variables associated with AP were evaluated at the time of admission for delivery. RESULTS: A total of 2834 consecutive subjects were included. Placenta accreta without placenta previa was observed in six cases (0.2 %). Two cases in which the placenta was located on the previous uterine scar had AP, but AP was found only in 0.1 % of cases in which the placenta was not on the previous scar (p < 0.001). AP was frequently observed in cases with a history of previous uterine surgery compared to cases without a history [(1.9 vs. 0.1 %) p < 0.001]. AP was observed in 33 % of cases in which no retroplacental clear zone was detected, whereas AP was observed in only 0.1 % of cases with a clear zone (p < 0.001). CONCLUSION: A past history of uterine surgery, ultrasonographic findings of no retroplacental clear zone, and a placenta on the uterine scar were associated with AP in cases without placenta previa.

Perinatal outcomes of cases with umbilical hypocoiled cord: a study at a single perinatal center.

OBJECTIVES: To evaluate the perinatal outcomes of hypocoiled cord. METHODS: This retrospective study was carried out in the Department of Obstetrics and Gynecology at Showa University Hospital between 2011 and 2017. Umbilical cord index (UCI) was calculated by dividing the total number of coils by the total length of umbilical cord. All umbilical cords were measured and calculated coiling index by obstetrician after delivery. Perinatal outcomes like non-reassuring fetal status (NRFS), emergency cesarean sections, and other perinatal complications were compared. RESULTS: From January 2011 to December 2017, a total of 4047 fetuses were born at our hospital after 28 weeks' gestation. After excluding 100 fetuses of hypercoiled cord, a total of 3947 fetuses were included in this study, of which 71 fetuses were hypocoiled cord and 3876 fetuses were normal coiled cord. There were no association between maternal background and both UCI group. NRFS during labor was significantly associated with hypocoiled cord compared with normal cord (p = .02). Additionally, the rates of emergency cesarean section were raised in cases of hypocoiled cord (p = .02). CONCLUSION: In this study, it was found that hypocoiled cord is related to NRFS and emergency cesarean section. In addition, hypocoiled cord was not associated with any maternal factors. However, in previous studies, no opinion has been reported on the timing of diagnosis of hypocoiled cord during pregnancy. It is difficult to evaluate hypocoiled cord correctly in third trimester. It is a task to find the hypocoiled cord correctly before birth.

Ultrasonographic study of umbilical cord twist direction during second trimester.

OBJECTIVE: To explore/study/evaluate the relationships among umbilical twist direction, the degree of umbilical twist and differences of umbilical arterial diameters (UAD). METHODS: All obstetric patients presenting for prenatal care of singleton fetuses between 18 and 25 weeks gestation to a single provider (MN) from 2015 to 2018 had detailed umbilical cord Doppler measurements. Data including the cord twist direction, degree of twist and number of twists per cord segment length, and the diameters of each UA (UAD) and the umbilical vein (UVD) were extracted from the records. UAs were described as right or left depending on their position at the fetal cord insertion. Three groups were identified: Group A: right UAD > left UAD and Group B: left UAD > right UAD Group C: equal UAD. The coiling index was calculated as the inverse of the length of cord required for one complete 360 degrees wrap of the UA around the cord. According to the difference of UADs, the variables of right and left UADs, the coiling index, and frequencies of umbilical twist direction were analyzed using non-parametric methods. RESULTS: 485 singleton fetuses and umbilical cords were examined. The value of the antenatal coiling index in cases with left UAD greater than right was 0.43 ± 0.16, which was significantly higher than 0.38 ± 0.16 with right UAD greater than left (p = .001). There were significant differences between the two groups in the values of right and left UAD, value of right minus left UAD, absolute value between right and left UAD, antenatal coiling index, antenatal coiling index due to umbilical twist direction and frequencies of cord twist direction. CONCLUSION: The direction of umbilical twist may be in part dependent on differences in diameters of the umbilical arteries, in addition to other fetal characteristics such as fetal movement, or handedness of fetus or mother, fetal hemodynamic forces and structure of muscles of umbilical vessels.