Search

• In Japan, the frequency of preterm birth is lower compared with elsewhere. • The treatment for preterm labour in Japan is commonly long-term tocolysis with ritodrine hydrochloride. • The treatment for preterm labour in Europe and the USA is short-term tocolysis. • We compared long-term and short-term tocolysis protocols for preterm labour. • A long-term tocolysis protocol does not contribute to lower frequency of preterm birth. To investigate whether the short-term tocolysis protocol is as effective as the traditional long-term tocolysis protocol with intravenous ritodrine hydrochloride for preterm labour. This single-centre, retrospective, observational study was conducted at Kitano Hospital, Osaka, Japan between April 2016 and July 2021. At the study hospital, the management protocol for preterm labour after 26 weeks of gestation was changed from the long-term tocolysis protocol to the short-term tocolysis protocol in November 2019. This study compared patients managed with the two protocols, using propensity score analysis to overcome the potential weaknesses of a retrospective study. The primary outcome was the frequency of preterm birth before 34 weeks of gestation before and after the protocol was revised. The secondary outcomes were frequency of neonatal intensive care unit admission and frequency of neonatal chronic lung disease. The study population consisted of 82 patients managed by the long-term tocolysis protocol and 56 patients managed by the short-term tocolysis protocol. After propensity score-weighted adjustment, the median durations of intravenous ritodrine administration in the long-term and short-term protocols were 18 days and 3 days, respectively. Differences were not detected between the long-term and short-term protocols in terms of the frequency of preterm delivery before 34 weeks of gestation [23.7 % vs 21.6 %, risk ratio (RR) 0.91, 95 % confidence interval (CI) 0.47–1.77], frequency of neonatal intensive care unit admission due to preterm birth (49.5 % vs 39.3 %, RR 0.79, 95 % CI 0.53–1.19) and frequency of neonatal chronic lung disease (4.4 % vs 9.2 %, RR 2.07, 95 % CI 0.51–8.48). Using propensity score analysis, changing from the long-term tocolysis protocol to the short-term tocolysis protocol for the management of preterm labour after 26 weeks of gestation did not have a negative effect on the frequency of preterm birth or neonatal prognosis. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the pregnancy outcomes of preterm premature rupture of membranes (preterm PROM; PPROM) by gestational age. Methods: This cohort study analyzed data from the Japan Environment and Children's Study. Pregnancy outcomes were documented using descriptive statistics. Logistic regression was used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) of complications. Results: Data were collected for 104 062 fetuses, and 99 776 were eligible for inclusion. The incidences of early (18–23 weeks) and late (24–36 weeks) PPROM were 0.1% (n = 102) and 1.2% (n = 1205), respectively. Of the 1307 cases, 66 (5.0%) resulted in miscarriage or stillbirth. Overall, 85.6% (1119/1307) resulted in preterm births, and 9.3% (122/1307) in term births. There was a higher incidence of oligohydramnios (OR 6.82, 95% CI 4.07, 11.4; OR 2.42, 95% CI 1.72, 3.40), intrauterine infection (OR 11.9, 95% CI 7.06, 19.9; OR 4.39, 95% CI 3.01, 6.41), cesarean delivery (OR 3.31, 95% CI 2.32, 4.71; OR 1.34, 95% CI 0.97, 1.85), placental abruption (OR 5.57, 95% CI 2.30, 13.5; OR 5.40, 95% CI 3.58, 8.14), and 5‐min Apgar score <7 (OR 35.3, 95% CI 21.5, 57.9; OR 2.66, 95% CI 1.75, 4.05) for early and late, compared to no, PPROM, respectively. Miscarriage or stillbirth was higher in early (OR 5.84, 95% CI 3.72, 9.15) and lower in late (OR 0.21, 95% CI 0.06, 0.68) compared to those without PPROM. Conclusions: This study described the epidemiology of pregnancy outcomes of early (occurring at the limit of viability) and late PPROM. [ABSTRACT FROM AUTHOR]

Aims: To determine the contribution of twin-to-twin transfusion syndrome (TTTS) to preterm birth (PTB) at <37 weeks of gestation among Japanese twin pregnancies. Methods: An observational study using 3241 MC-BA (monochorionic biamniotic) and 6581 BC (bichorionic biamniotic) twin pregnancies. We focused on TTTS, preterm premature rupture of membranes (PPROM), pregnancy-induced hypertension (PIH), and fetal sex as possible causes of PTB. Results: PTB was more common in MC-BA than in BC twin pregnancies (66.9% vs. 57.6%, P<0.0001) whereas PTB after PPROM (8.0% vs. 10.0%) and PIH (5.7% vs. 5.9%) was not. PTB after TTTS occurred in 7.3% of women with MC-BA twins. PTB was significantly more common for male-male pairs than for female-female pairs among both MC-BA (69.2% vs. 64.7%) and BC (59.6% vs. 56.3%) twins. Conclusion: The elevated risk of PTB among MC-BA twins could be explained by the occurrence of TTTS. [ABSTRACT FROM AUTHOR]

This study aimed to clarify the association between uterine myomas and preterm birth (PTB), preterm premature rupture of membranes (pPROM), and intrauterine infection (II). The study was based on data from the Japan Environment and Children's Study, a nationwide birth-cohort study. Data of 86,370 women with singleton births after 22 weeks of gestation (with uterine myomas, n = 5354) were retrospectively analyzed. Using logistic regression, adjusted odds ratios (aORs) for PTB, pPROM, and II were calculated considering women without uterine myomas as the reference. Additionally, the effects of II on the incidence of PTB and pPROM were evaluated. In women with uterine myomas, the aORs for PTB before 37 and 34 weeks, pPROM, and II were 1.37 (95% confidence interval, 1.22-1.54), 1.61 (1.27-2.05), 1.65 (1.33-2.04), and 1.05 (0.75-1.46), respectively. The aORs for PTB and pPROM in women with II and uterine myomas were not significantly increased. Uterine myomas during pregnancy were associated with an increased incidence of PTB and pPROM. However, II in women with uterine myomas was not associated with an increased incidence of PTB or pPROM. These findings suggest a potential risk of occult PTB in pregnant women with uterine myomas., Competing Interests: The authors declare no conflicts of interest.

The aim of this study was to clarify the risk factors for chlamydial infection and determine whether infection during pregnancy is associated with preterm birth in Japanese women. The subjects were women who underwent Chlamydia trachomatis polymerase chain reaction testing during a singleton pregnancy and delivered after the 22nd week of gestation at a tertiary care center between January 1, 2000 and December 31, 2016. We compared Chlamydia-positive (n = 259) and Chlamydianegative (n = 1,974) groups and evaluated the pregnancy outcomes. The Chlamydia-positive group had a higher rate of public assistance coverage, smoking during pregnancy, nulliparity, lack of a partner, presence of other sexually transmitted infections, high-risk social status, and younger age (P < 0.01). The incidence of preterm births was not different between the groups, with an odds ratio of 0.95 (95% confidence interval: 0.62-1.46). The incidences of low birth weight deliveries, premature rupture of membranes, and preterm premature rupture of membranes prior to the 37th week were also comparable between the groups. Chlamydial infection during pregnancy had no effect on preterm birth, even after adjustment for confounding factors.