Report from "International Workshop for Junior Fellows 2: Tocolytic treatment for prevention of preterm birth" at the 73rd Annual Congress of the Japan Society of Obstetrics and Gynecology

Association Between Atopic Dermatitis in Pregnant Women and Preterm Births: The Japan Environment and Children's Study

OBJECTIVES

This study aimed to evaluate the association between atopic dermatitis in pregnant women and preterm births, accounting for maternal ritodrine hydrochloride administration status.

METHODS

Data of 83,796 women with singleton pregnancies at and after 22 weeks of gestation (enrolled between 2011 and 2014) were analyzed. These data were obtained from the Japan Environment and Children's Study. Atopic dermatitis was defined based on self-reported questionnaire responses obtained during the first trimester. The primary outcome measures were preterm births before 37, 32, and 28 weeks of gestation. Using a multivariable logistic regression model, odds ratios for preterm births in pregnant women with atopic dermatitis were calculated, with women without atopic dermatitis included in the reference group. This analysis considered confounding factors and maternal ritodrine hydrochloride administration.

RESULTS

Among pregnant women with atopic dermatitis, the adjusted odds ratios (95% confidence intervals) for preterm births before 37, 32, and 28 weeks of gestation were 0.89 (0.81-0.98), 0.98 (0.74-1.30), and 0.88 (0.50-1.55), respectively. This trend remained consistent after excluding participants who received ritodrine hydrochloride.

CONCLUSIONS FOR PRACTICE

Atopic dermatitis in pregnant women was significantly associated with a decreased incidence of preterm births before 37 weeks of gestation, even after accounting for the effects of maternal ritodrine hydrochloride administration.

Tocolytic treatment and maternal characteristics, obstetric outcomes, and offspring childhood outcomes among births at and after 37 weeks of gestation: the Japan environment and children's study

PURPOSE

To evaluate differences in maternal characteristics and obstetric and offspring childhood outcomes between births at and after 37 weeks of gestation (referred to as term and post-term births) according to the use of tocolytic treatment.

METHODS

Data for 63,409 women with singleton births at and after 37 weeks of gestation were analyzed using data from the Japan Environment and Children's Study (JECS). We compared maternal characteristics, obstetric outcomes, and offspring childhood outcomes between term and post-term births exposed and not exposed to tocolytic treatment. Additionally, multivariable logistic regression models were used to calculate adjusted odds ratios for offspring childhood outcomes with significant between-group differences in the univariable analysis, with term and post-term births without tocolytic agents as the reference group.

RESULTS

We observed differences in maternal characteristics and obstetric outcomes between term and post-term births exposed and not exposed to tocolytic treatment. The incidence of offspring childhood developmental disorders showed no significant between-group differences. However, participants exposed to tocolytic agents had higher incidence of offspring childhood allergic disorders. The adjusted odds ratio for any of the offspring childhood allergic disorders in term and post-term births with tocolytic agents was 1.08 (95% confidence interval, 1.03-1.13).

CONCLUSION

This study found no significant difference in the incidence of offspring developmental disorders between term and post-term births exposed and not exposed to tocolytic treatment. However, tocolytic treatment was associated with differences in maternal characteristics and obstetric outcomes, along with a marginal increase in the incidence of childhood allergic disorders in offspring.

Relationship between prolonged gestation and nifedipine pharmacokinetics in long-term tocolysis

In this study, we examined the pharmacokinetics of nifedipine and investigated the maternal and foetal background factors that prolong pregnancy in pregnant women undergoing long-term tocolysis. This prospective observational study included 38 pregnant women hospitalised for threatened preterm labour and treated with nifedipine extended-release tablets in combination with an intravenous ritodrine infusion. Maternal plasma nifedipine concentrations were determined using high-performance liquid chromatography. All patients were administered 20 or 40 mg/dose of nifedipine every 6 h at the time of blood sampling. The plasma trough concentration (Ctrough ) was 22.6 ± 17.3 ng/mL, the maximum plasma concentration (Cmax ) was 30.9 ± 15.3 ng/mL and the time to maximum concentration (Tmax ) was 1.70 ± 1.10 h, as determined using noncompartmental analysis (NCA). The area under the curve for drug concentration (AUCtau ) was 152.3 ± 91.8 mg/L・h, and oral clearance (CL/F) was 0.17 ± 0.08 L/h. Using logistic regression analyses, we identified the factors that predicted term delivery from 37 weeks to <42 weeks of gestation. Gestational age at admission and the AUCtau of nifedipine can predict term delivery. The AUCtau of nifedipine is a valuable regulatory predictor of term delivery in pregnant women undergoing long-term tocolysis.

Association between gestational age at threatened preterm birth diagnosis and incidence of preterm birth: the Japan Environment and Children's Study

We evaluated the association between gestational age at threatened preterm birth (TPTB) diagnosis and preterm birth (PTB) incidence using a nationwide birth cohort. Data of 94,236 women with singleton deliveries from the Japan Environment and Children's Study (enrolled between 2011 and 2014) were analysed. Participants were divided based on parity and gestational age at TPTB diagnosis (22-24, 25-27, 28-30, 31-33, and 34-36 weeks). Multivariable logistic regression models were used to calculate the odds ratios (ORs) for PTB before 37 and 34 weeks in women from all groups, using participants without TPTB as the reference. The adjusted ORs for PTB before 37 weeks were the highest in the latest gestational age group in nulliparous and multiparous women without previous PTB, while those before 34 weeks were the highest in the earliest and latest gestational age group in multiparous women without previous PTB and in the earliest gestational age group in multiparous women with previous PTB. The association between gestational age at TPTB diagnosis and PTB incidence varies based on maternal parity and PTB before 37 or 34 weeks. Further studies with detailed clinical data and a unified TPTB diagnosis protocol are necessary to clarify this association.

Atosiban-induced acute pulmonary edema: A rare but severe complication of tocolysis

Background

Atosiban is commonly used to delay premature labor in pregnant women and is thought to have few side effects.

Objectives

To report a case of acute pulmonary edema (APE) following administration of atosiban and conduct a systematic review to identify common characteristics and risk factors of atosiban-associated APE.

Methods

Searches were performed in Pubmed, Embase, and Web of Science using the keyword "Atosiban" combined with the terms "Pulmonary edema" or "Dyspnea" or "Hypoxia" on 9th July 2022. Only case reports of atosiban-associated APE were included without language restrictions. Data were extracted from the reports, and median, range, and percentages were calculated as applicable. The risk of bias was assessed using the Joanna Briggs Institute critical appraisal checklist for case reports.

Results

Seven cases of atosiban-associated APE were included in the systematic review, including our case. APE occurred at a median gestational age of 32 + 6 weeks. Most patients were nulliparous (6/7, 85.7%) and were in multiple pregnancies (5/7, 71.4%). All patients were prescribed antenatal corticosteroids and tocolytics, with three (42.9%) receiving only atosiban and four (57.1%) receiving atosiban and other tocolytics. The median interval from starting atosiban administration to APE onset was about 40 h, and three patients (42.9%) showed symptoms 2-10 h after the end of atosiban treatment. Radiographic examinations (chest X-ray and/or computer tomography scan) confirmed APE in all patients and pleural effusion in four patients (57.1%). Five patients (71.4%) underwent emergency cesarean section, one patient (14.3%) with twin pregnancy had vaginal delivery with the help of suction cup and forceps, and another patient (14.3%) continued the pregnancy. All patients recovered well after administration of oxygen, diuresis, and other supportive therapy.

Conclusion

Atosiban may cause acute pulmonary edema in patients with underlying risk factors. This complication remains rare, but caution during tocolytic treatment using atosiban is recommended.

Effects of maternal ritodrine hydrochloride administration on the heart rate of preterm fetal sheep with intraamniotic inflammation

Ritodrine hydrochloride is used for pregnancy prolongation and intrauterine fetal resuscitation. However, its clinical significance in intraamniotic inflammation during preterm labor and intrauterine fetal distress is unclear. We investigated the effects of maternal ritodrine hydrochloride administration (MRA; 200 μg/min for 2 h, followed by 800 μg/min for 2 h after 24 h) on fetal physiological parameters. For this purpose, we used chronically instrumented pregnant sheep at 113–119 d (term = 145 d) of gestation without (Group 1, n = 5) and with (Group 2, n = 5) intraamniotic inflammation induced by lipopolysaccharide injection into the amniotic cavity. The changes in fetal heart rate (FHR) and short-term variability (STV) and long-term variability (LTV) in FHR, fetal blood pressure, and fetal arterial blood gas (FABG) values were measured before and at 1 and 2 h after initiating MRA. Before MRA, all parameters were similar between Groups 1 and 2; however, there was significantly higher STV in Group 2 than in Group 1 before MRA at 800 μg/min, significantly higher partial arterial pressure of carbon dioxide in FABG in Group 2 than in Group 1 before MRA at 200 μg/min, and significantly lower blood glucose (BG) in Group 2 than in Group 1 before MRA at 800 μg/min. One hour after MRA, the FHR, STV, and LTV were significantly higher at 800 μg/min than those at the baseline in Group 1, as determined by the Friedman test; however, no significant difference was observed in Group 2. Additionally, the FABG pH significantly decreased 1 h after MRA at 800 μg/min in Group 2, whereas FABG lactate and BG significantly increased 2 h after MRA at 800 μg/min in Groups 1 and 2. Thus, short-term MRA at 800 μg/min increased the FHR, STV, and LTV significantly; these values were further modified under intraamniotic inflammation.