Maternal exercise during pregnancy reduces the risk of preterm birth through the mediating role of placenta

Physical activity during pregnancy and adverse birth outcome: a prospective cohort study in China

Objectives The relationship between prenatal physical activity (PA) and adverse birth outcomes is still inconclusive. We aimed to investigate the association between PA during pregnancy and adverse birth outcomes by using data from the Guangxi Zhuang birth cohort (GZBC) in China.Study Design A total of 11,292 mother-infant pairs were included from GZBC in China. The information on PA status, intensity, adequacy, and volume and birth outcomes were collected. Multivariable linear and logistic regression models were applied to analyze the effects of PA during pregnancy on birth weight z-scores (BW z-scores) and gestational age and risk of small-for-gestational age (SGA) and preterm birth (PTB), respectively. Cubic spline analysis was conducted to detect a nonlinear dose-response of total weekly activity metabolic equivalents (MET) and birth outcomes.Results Compared to no regular PA during pregnancy, moderate and high-intensity PA (MVPA) was associated with increase BW z-scores (β = 0.08, 95%CI: 0.002, 0.15, p = .044) and associated with a marginal significant decrease in risk of PTB (OR = 0.73, 95%CI: 0.51, 1.05, p = .093). However, PA had no relationship with gestational age and risk of SGA, and Nonlinear relationships were not observed between total weekly activity MET and risk of SGA and PTB.Conclusion These finding shows that PA during pregnancy may increase the BW z-score and reduce risk of PTB, supporting the guidelines that pregnant women should be encouraged to engage in appropriate physical activity during pregnancy in China.

Maternal Exercise Prior to and during Gestation Induces Sex-Specific Alterations in the Mouse Placenta

While exercise (EX) during pregnancy is beneficial for both mother and child, little is known about the mechanisms by which maternal exercise mediates changes in utero. Six-week-old female C57BL/6 mice were divided into two groups: with (exercise, EX; N = 7) or without (sedentary, SED; N = 8) access to voluntary running wheels. EX was provided via 24 h access to wheels for 10 weeks prior to conception until late pregnancy (18.5 days post coitum). Sex-stratified placentas and fetal livers were collected. Microarray analysis of SED and EX placentas revealed that EX affected gene transcript expression of 283 and 661 transcripts in male and female placentas, respectively (±1.4-fold, p < 0.05). Gene Set Enrichment and Ingenuity Pathway Analyses of male placentas showed that EX led to inhibition of signaling pathways, biological functions, and down-regulation of transcripts related to lipid and steroid metabolism, while EX in female placentas led to activation of pathways, biological functions, and gene expression related to muscle growth, brain, vascular development, and growth factors. Overall, our results suggest that the effects of maternal EX on the placenta and presumably on the offspring are sexually dimorphic.

Sports Obstetrics: Implications of Pregnancy in Elite Sportswomen, a Narrative Review

Increasing numbers of females are participating in elite sports, with a record number having competed at the Tokyo Olympic Games. Importantly, the ages of peak performance and fertility are very likely to coincide; as such, it is inevitable that pregnancy will occur during training and competition. Whilst there is considerable evidence to promote regular exercise in pregnancy, with benefits including a reduction in hypertensive disorders, gestational diabetes, and reduced rates of post-natal depression, few studies have been conducted which include elite athletes. Indeed, there are concerns that high-intensity exercise may lead to increased rates of miscarriage and preterm labour, amongst other pregnancy-related complications. There is minimal guidance on the obstetric management of athletes, and consequently, healthcare professionals frequently adopt a very conservative approach to managing such people. This narrative review summarises the evidence on the antenatal, intrapartum, and postpartum outcomes in elite athletes and provides recommendations for healthcare providers, demonstrating that generally, pregnant athletes can continue their training, with a few notable exceptions. It also summarises the physiological changes that occur in pregnancy and reviews the literature base regarding how these changes may impact performance, with benefits arising from pregnancy-associated cardiovascular adaptations at earlier gestations but later changes causing an increased risk of injury and fatigue.

Nocturnal Lifestyle Behaviours and Risk of Poor Sleep during Pregnancy

The extent to which lifestyle practices at night influence sleep quality in pregnant women remains unknown. This study aimed to examine whether nocturnal behaviours were associated with poor sleep during pregnancy. We performed a cross-sectional analysis of a prospective cohort of pregnant women at 18–24 gestation weeks recruited from KK Women’s and Children’s Hospital, Singapore, between 2019 and 2021. Nocturnal behaviours were assessed with questionnaires, and sleep quality was measured using the Pittsburgh Sleep Quality Index (PSQI) with a global score ≥5 indicative of poor sleep quality. Modified Poisson regression and linear regression were used to examine the association between nocturnal behaviour and sleep quality. Of 299 women, 117 (39.1%) experienced poor sleep. In the covariate-adjusted analysis, poor sleep was observed in women with nocturnal eating (risk ratio 1.51; 95% confidence interval [CI] 1.12, 2.04) and nocturnal artificial light exposure (1.63; 1.24, 2.13). Similarly, nocturnal eating (β 0.68; 95% CI 0.03, 1.32) and light exposure (1.99; 1.04, 2.94) were associated with higher PSQI score. Nocturnal physical activity and screen viewing before bedtime were not associated with sleep quality. In conclusion, reducing nocturnal eating and light exposure at night could potentially improve sleep in pregnancy.

The impact of COVID-19 first wave national lockdowns on perinatal outcomes: a rapid review and meta-analysis

BACKGROUND

Since the emergence of COVID-19, preventative public health measures, including lockdown strategies, were declared in most countries to control viral transmission. Recent studies and anecdotes have reported changes in the prevalence of perinatal outcomes during national COVID-19lockdowns.The objective of this rapid review was to evaluate the impact of COVID-19 lockdowns on the incidence of low birth weight (LBW), preterm birth (PTB), and stillbirth.

METHODS

Two reviewers searched EMBASE, CORD-19, LitCovid (PubMed), WHO Global research on corona virus disease (COVID-19), and MedRxiv for studies published in English from the first reports on COVID-19 until 17 July 2021. Perinatal outcomes of interest included LBW (< 2500 g), PTB (< 37 weeks), and stillbirth.

RESULTS

Of the 1967 screened articles, 17 publications met the inclusion criteria (14 cohort studies, 1 case control and 2 cross-sectional studies). Studies included data from Denmark, UK, Ireland, Nepal, Italy, Israel, Botswana, Australia, China, Netherlands, Saudi Arabia, Austria, Zimbabwe, India, and Spain. The total sample size ranged from 3399 to 1,599,547 pregnant women. Thirteen studies examined PTB with conflicting results, reporting both an increase and a decrease in PTB incidence, with odds ratios [95% CI] ranging from 0.09 [0.01, 0.40] to 1.93 [0.76, 4.79]. Three studies found a decrease in LBW rates during lockdowns, one of which was statistically significant, with a rate ratio of 3.77 [1.21, 11.75]. Ten studies examined stillbirth rates, including four studies reporting a statistically significant increase in stillbirth rates, with adjusted relative risk ranging from 1.46 [1.13, 1.89] to 3.9 [1.83, 12.0]. Fourteen studies contained data that could be combined in a meta-analysis comparing perinatal outcomes before and during lockdown. We found that lockdown measures were associated with a significant risk of stillbirth with RR = 1.33 [95% CI 1.04, 1.69] when compared to before lockdown period. However, lockdown measures were not associated with a significant risk of PTB, LBW and VLBW compared to prepandemic periods.

CONCLUSIONS

This review provides clues about the severity of the indirect influence of COVID-19 lockdown implementation; however, the criteria that lead to unexpected changes in LBW, PTB, and stillbirth remains unclear. Large studies showed conflicting results, reporting both increases and decreases in selected perinatal outcomes. Pooled results show a significant association between lockdown measures and stillbirth rates, but not low birth weight rates. Further studies examining the differences in other countries' lockdowns and sociodemographic groups from low to middle-income countries are needed. Exploration of perinatal outcomes during COVID-19 lockdown poses an opportunity to learn from and make changes to promote the reduction of the leading causes of childhood mortality worldwide.

Prenatal exercise in fetal development: a placental perspective

Maternal obesity (MO) and gestational diabetes mellitus (GDM) are common in Western societies, which impair fetal development and predispose offspring to metabolic dysfunction. Placenta is the organ linking the mother to her fetus, and MO suppresses the development of vascular system and expression of nutrient transporters in placenta, thereby affecting fetal development. For maintaining its proper physiological function, placenta is energy demanding, which is met through extensive oxidative phosphorylation. However, the oxidative capacity of placenta is suppressed due to MO and GDM. Recently, several studies showed that physical activity during pregnancy enhances oxidative metabolism and improves placental function, which might be partially mediated by exerkines, referring to cytokines elicited by exercise. In addition, as an endocrine organ, placenta secretes cytokines, termed placentokines, including apelin, superoxide dismutase 3, irisin, and adiponectin, which mediate fetal development and maternal metabolism. Possible molecular mechanisms linking maternal exercise and placentokines to placental and fetal development are further discussed. As an emerging field, up to now, available studies are limited, mostly conducted in rodents. Given the epidemics of obesity and metabolic disorders, as well as the prevalence of maternal sedentary lifestyle, the effects of exercise of pregnant women on placental function and placentokine secretion, as well as their impacts on fetal development, need to be further examined.

Placental weight mediates association between prenatal exposure to cooking oil fumes and preterm birth

Background: There are some reports on association between maternal prenatal cooking oil fume (COF) exposure and preterm birth (PTB), but its mechanism remains poorly understood. Therefore, this study aims to assess whether placental weight mediates their associations.Method: We enrolled 619 pregnant women delivering PTB newborns as cases and 1701 delivering full-term appropriate for gestational age newborns as controls. They were inquired with a self-reported questionnaire about prenatal COF exposure, socio-demographics and obstetric characteristics at Women and Children's Hospitals of Shenzhen and Foshan. After controlling for the potential confounders, a series of logistic and linear regressions were conducted to assess associations among COF exposure, placental weight and PTB, and the mediation of placental weight in the association between COF exposure and PTB.Results: Maternal prenatal COF exposure was significantly associated with PTB and the frequency of prenatal COF exposure was negatively associated with placental weight. Compared with mother who never cooked, those cooking occasionally, sometimes or often increased the risk of PTB, and similarly, those cooking between half to an hour was also showed a higher risk of PTB. Typical Chinese cooking methods including stir-frying, pan-frying and deep-frying were also associated with PTB. Different oil types mainly used, including peanut oil, corn oil and animal oil were associated with PTB as well. Mediation analysis illustrated that placental weight partially mediated 13.60% (95% CI = 10.62-33.20%) of the effects on the association between the frequency of maternal prenatal COF exposure and PTB.Conclusion: Maternal cooking during pregnancy and the frequency of prenatal COF exposure might increase the risk of PTB, in which placenta might play mediation role.

The Mediating Role of Placental Weight Change in the Association Between Prenatal Exposure to Thallium and Birth Weight: A Prospective Birth Cohort Study

Background: Previous studies have demonstrated the embryotoxicity and fetotoxicity of thallium (Tl). However, the effects of prenatal exposure to Tl on birth weight and placental weight and the mediating role of placental weight in the association of Tl with birth weight remain unclear.

Methods: We recruited 2,748 participants from the ongoing Prenatal Environment and Offspring Health Cohort (PEOH Cohort) study, which was initiated in 2016 in Guangzhou, China. The Tl concentrations in maternal urine samples collected during the first and third trimester were determined by inductively coupled plasma mass spectrometry. Birth weight and placental weight were extracted from maternal medical records.

Results: Pregnant women exposed to the highest tertile of Tl in the first trimester (β = −42.7 g, 95% CI: −82.3, −3.1 g) and third trimester (β = −50.6 g, 95% CI: −99.0, −2.3 g) had babies with lower birth weights than those exposed to the lowest tertile. We also found significant negative associations of exposure to Tl concentrations in the first and third trimester with placental weight. Mediation analyses showed that 50.3% (95% CI: 15.9, 79.2%) and 33.5% (95% CI: 1.3, 80.3%) of the effects of Tl exposure in the first and third trimester on birth weight were mediated by decreased placental weight.

Conclusion: Our results suggest that prenatal exposure to Tl is negatively associated with birth weight and that this association may be mediated by decreased placental weight.

Effects of Maternal Exercise During Pregnancy on Perinatal Growth and Childhood Obesity Outcomes: A Meta-analysis and Meta-regression

BACKGROUND

Perinatal growth abnormalities program susceptibility to childhood obesity, which is further exaggerated by maternal overweight and obesity (MO) during pregnancy. Exercise is highly accessible, but reports about the benefits of maternal exercise on fetal growth and childhood obesity outcomes are inconsistent, reducing the incentives for pregnant women to participate in exercise to improve children's perinatal growth.

OBJECTIVE

This systematic review and meta-analysis aims to establish evidence-based efficacy of exercise in mothers with normal weight (MNW) and MO during pregnancy in reducing the risks of perinatal growth abnormalities and childhood obesity. In addition, the impacts of exercise volume are also assessed.

METHODS

The PubMed, ScienceDirect, Web of Science, and Cochrane Library databases were searched from inception to February 15, 2020. We included randomized controlled trials with exercise-only intervention or exercise with other confounders in pregnant MNW (body mass index, BMI 18.5-24.9 kg/m²) and MO (BMI ≥ 25 kg/m²), which were further subgrouped in the meta-analysis. Primary outcomes included birth weight, preterm birth, small for gestational age (SGA), large for gestational age (LGA), infant and childhood weight, and childhood obesity. A linear meta-regression analysis was also used to explore the effects of exercise volume on outcomes.

RESULTS

99 studies were included in the meta-analysis (n = 596,876), and individual study quality ranged from fair to good according to the Newcastle-Ottawa scale assessment. Exercise only interventions in MNW reduced preterm birth by 15% (26 studies, n = 76,132; odds ratio [OR] 0.85; 95% CI 0.72, 1.01; I² = 83.3%), SGA by 17% (33 studies, n = 92,351; OR 0.83; 95% CI 0.71, 0.98; I² = 74.5%) and LGA by 17% (29 studies, n = 84,310; OR 0.83; 95% CI 0.74, 0.95; I² = 60.4%). Exercise only interventions in MO reduced preterm birth by 33% (2 studies, n = 3,050; OR 0.67; 95% CI 0.70, 0.96; I² = 0%), SGA by 27% (8 studies, n = 3,909; OR 0.73; 95% CI 0.50, 1.05; I² = 40.4%) and LGA by 55% (9 studies, n = 81,581; OR 0.45; 95% CI 0.18, 1.11; I² = 98.3%). Exercise only interventions in MNW reduced childhood obesity by 53% (3 studies, n = 6,920; OR 0.47; 95% CI 0.36, 0.63; I² = 77.0%). However, no significant effect was observed in outcomes from exercise confounders in either MNW or MO. In the meta-regression, the volume of exercise-only intervention in MNW was negatively associated with birth weight, greatly driven by volumes more than 810 metabolic equivalents (MET)-min per week. Other outcomes were not associated with exercise volume.

CONCLUSIONS

This systematic review and meta-analysis suggests that exercise during pregnancy in both MNW and MO safely and effectively reduce the risks of preterm birth, SGA, and LGA. Furthermore, MNW exercise also reduces the risk of childhood obesity. Overall, regardless of prepregnancy BMI, maternal exercise during pregnancy provides an excellent opportunity to mitigate the high prevalence of adverse birth outcomes and childhood obesity.

Does exercise during pregnancy impact organs or structures of the maternal-fetal interface?

Exercise during pregnancy has been shown to be associated with improved health outcomes both during and after pregnancy for mother and fetus across the lifespan. Increasing physical activity and reducing sedentary behaviour during pregnancy have been recommended by many researchers and clinicians-alike. It is thought that the placenta plays a central role in mediating any positive or negative pregnancy outcomes. The positive outcomes obtained through prenatal exercise are postulated to result from exercise-induced regulation of maternal physiology and placental development. Considerable research has been performed to understand the placenta's role in pregnancy-related diseases, such as preeclampsia, fetal growth restriction, and gestational diabetes mellitus. However, little research has examined the potential for healthy lifestyle and behavioural changes to improve placental growth, development, and function. While the placenta represents the critical maternal-fetal interface responsible for all gas, nutrient, and waste exchange between the mother and fetus, the impact of exercise during pregnancy on placental biology and function is not well known. This review will focus on prenatal exercise and its promising influence on the structures of the maternal-fetal interface, with particular emphasis on the placenta. Potential molecular mechanistic hypotheses are presented to aid future investigations of prenatal exercise and placental health.

Structured supervised exercise training or motivational counselling during pregnancy on physical activity level and health of mother and offspring: FitMum study protocol

INTRODUCTION

A physically active lifestyle during pregnancy improves maternal and offspring health but can be difficult to follow. In Denmark, less than 40% of pregnant women meet physical activity (PA) recommendations. The FitMum study aims to explore strategies to increase PA during pregnancy among women with low PA and assess the health effects of PA. This paper presents the FitMum protocol, which evaluates the effects of structured supervised exercise training or motivational counselling supported by health technology during pregnancy on PA level and health of mother and offspring.

METHODS AND ANALYSIS

A single-site three-arm randomised controlled trial that aims to recruit 220 healthy, pregnant women with gestational age (GA) no later than week 15 and whose PA level does not exceed one hour/week. Participants are randomised to one of three groups: structured supervised exercise training consisting of three weekly exercise sessions, motivational counselling supported by health technology or a control group receiving standard care. The interventions take place from randomisation until delivery. The primary outcome is min/week of moderate-to-vigorous intensity PA (MVPA) as determined by a commercial activity tracker, collected from randomisation until GA of 28 weeks and 0-6 days, and the secondary outcome is gestational weight gain (GWG). Additional outcomes are complementary measures of PA; clinical and psychological health parameters in participant, partner and offspring; analyses of blood, placenta and breastmilk samples; process evaluation of interventions; and personal understandings of PA.

ETHICS AND DISSEMINATION

The study is approved by the Danish National Committee on Health Research Ethics (# H-18011067) and the Danish Data Protection Agency (# P-2019-512). Findings will be disseminated via peer-reviewed publications, at conferences, and to health professionals via science theatre performances.

TRIAL REGISTRATION NUMBER

NCT03679130.

PROTOCOL VERSION

This paper was written per the study protocol version 8 dated 28 August 2019.

Association between maternal outdoor physical exercise and the risk of preterm birth: a case-control study in Wuhan, China

BACKGROUND

China had the second largest proportion of preterm birth (PTB) internationally. However, only 11% of pregnant women in China meet international guidelines for maternal physical activity, a significantly lower proportion than that in Western countries. This study aims to examine the association between outdoor physical exercise during pregnancy and PTB among Chinese women in Wuhan, China.

METHODS

A case-control study was conducted among 6656 pregnant women (2393 cases and 4263 controls) in Wuhan, China from June 2011 to June 2013. Self-reported measures of maternal physical exercise (frequency per week and per day in minutes) were collected. Adjusted odds ratios were estimated using Bayesian hierarchical logistic regression and a generalized additive mixed model (GAMM).

RESULTS

Compared to women not involved in any physical activity, those who participated in physical exercise 1-2 times, 3-4 times, and over five times per week had 20% (aOR: 0.80, 95% credible interval [95% CI]: 0.68-0.92), 30% (aOR: 0.70, 95% CI: 0.60-0.82), and 32% (aOR: 0.68, 95% CI: 0.59-0.78) lower odds of PTB, respectively. The Bayesian GAMM showed that increasing physical exercise per day was associated with lower risk of PTB when exercise was less than 150 min per day; however, this direction of association is reversed when physical exercise was more than 150 min per day.

CONCLUSION

Maternal physical exercise, at a moderate amount and intensity, is associated with lower PTB risk. More data from pregnant women with high participation in physical exercise are needed to confirm the reported U-shape association between the physical exercise and risk of preterm birth.

Cluster Analysis of the Combined Association of Sleep and Physical Activity with Healthy Behavior and Psychological Health in Pregnant Women

The purposes of the study were to (1) identify clusters based on patterns of sleep quality and duration and physical activity levels of healthy Korean pregnant women, and (2) subsequently investigate the association of identified clusters with pre-pregnancy healthy behaviors, depressive symptoms, and pregnancy stress. Two hundred eighty-four pregnant women participated in the study while attending a prenatal education program provided by a tertiary hospital in Seoul, Korea. The survey questionnaire consisted of the Pittsburg Sleep Quality Index, the International Physical Activity Questionnaire, and the Center for Epidemiologic Studies Depression scale. We used the Latent GOLD to identify distinct clusters and the chi-square test and ANOVA to compare clusters. We identified three clusters: ‘good sleeper’ (63.4%), ‘poor sleeper’ (24.6%), and ‘low activity’ (12.0%). Women in the good-sleeper cluster were more likely to have higher education and income levels and reported more healthy behaviors before pregnancy. Poor-sleeper and low-activity clusters were more likely to report higher scores in depressive symptoms and pregnancy stress (p < 0.001 and p = 0.005, respectively). Tailored intervention for pregnant women who are physically inactive or sleep poorly may promote their psychological well-being as well as bringing good obstetric outcomes.

Urban-Related Environmental Exposures during Pregnancy and Placental Development and Preeclampsia: a Review

PURPOSE OF REVIEW

To summarize the current knowledge of the pathophysiological implications and the clinical role of urban-related environmental exposures in pregnancy.

RECENT FINDINGS

The ongoing urbanization worldwide is leading to an increasing number of pregnant women being exposed to higher levels of urban-related environmental hazards such as air pollution and noise and, at the same time, having less contact with natural environments. Pregnancy represents a particular and vulnerable life period both for women and their children. Extensive physiological and metabolic changes, as well as changes to the cardiovascular and respiratory systems during pregnancy, could result in increased sensitivity to damage by environmental factors. Exposure to air pollution and noise is associated with placental dysfunction and damage, which, in turn, could lead to maternal complications such as preeclampsia. In contrast, more contact with greenspace during pregnancy seems to mitigate these adverse impacts. These findings open up new challenges for our understanding of the potential effect of urban living on placental function and preeclampsia, and offer new clinical and research opportunities.

The Mediating Role of Organizational Reputation and Trust in the Intention to Use Wearable Health Devices: Cross-Country Study

Background

The use of consumer wearable health devices for fitness tracking has seen an upward trend across the globe. Previous studies have shown that trust is an important factor in the adoption and use of new technologies. However, little is known about the influence of organizational reputation and trust on the intention to use wearable health devices.

Objective

This study aimed to investigate the mediating role of organizational reputation and trust in the intention to use wearable health devices and to examine the extent to which the country of residence influenced the effect of organizational reputation on consumers’ trust in and intention to use wearable health devices.

Methods

We conducted a cross-country survey with participants from Kenya and South Africa using a Google Forms questionnaire derived from previously validated items. A series of mediation regression analyses were carried out using the PROCESS macro with the bootstrap CI procedure. A one-way, between-group multivariate analysis of variance (MANOVA) was also used to determine the key factors that distinguish Kenyans and South Africans in their intention to use wearable health devices.

Results

A total of 232 questionnaire responses were collected. The results revealed that organizational reputation significantly mediates the relationship between trust propensity and trust, with an indirect effect of 0.22 (95% CI 0.143-0.309). Organizational reputation also plays a significant direct role in the intention to use a wearable health device, with a direct effect of 0.32 (95% CI 0.175-0.483). This role is regardless of participants’ country of residence. Furthermore, there is a significant mediating effect of trust on the relationship between trust propensity and the intention to use a wearable health device, with an indirect effect of 0.26 (95% CI 0.172-0.349); between perceived security and the intention to use a wearable health device, with an indirect effect of 0.36 (95% CI 0.255-0.461); and between perceived privacy and the intention to use a wearable health device, with an indirect effect of 0.42 (95% CI 0.282-0.557). The MANOVA test shows statistically significant differences in all variables for both groups, with the exception of organizational reputation where there is no significant difference between the two cohorts.

Conclusions

Organizational reputation has a significant direct influence on participants’ trust in and the intention to use a wearable health device irrespective of their country of residence. Even in the presence of perceived security and perceived privacy, trust has a significant mediating effect on the intention to use a wearable health device.

Association between rehabilitation during hospitalization and perinatal outcomes among pregnant women with threatened preterm birth

OBJECTIVE

This study conducted a nationwide retrospective cohort study to evaluate whether rehabilitation for pregnant women during long-term hospitalization is associated with adverse perinatal events.

METHODS

We performed a retrospective cohort study using a diagnosis procedure combination (DPC) database, a national inpatient database for acute-care inpatients in Japan. Hospitalized pregnant women diagnosed with threatened preterm birth, who stayed in the hospital for 7 days or longer from July 2010 to March 2017 in Japan were identified. One-to-four propensity score-matched analyses were performed to compare perinatal outcomes between patients with and without rehabilitation during hospitalization. The primary outcome was preterm birth (<35/0 weeks of gestation) during hospitalization.

RESULTS

Of the 141,705 eligible patients, 351 (0.25%) received any type of rehabilitation during hospitalization. One-to-four propensity score matching created a rehabilitation group (n = 338) and a nonrehabilitation group (n = 1352). The propensity-matched analysis showed that the proportion of preterm births in the rehabilitation group was lower than that in the nonrehabilitation group (5.9% versus 8.9%; risk difference: -3.0%; 95% confidence interval (CI): -5.9 to -0.03).

CONCLUSIONS

This retrospective nationwide study suggests that rehabilitation for hospitalized patients with threatened preterm birth may reduce the risk of preterm birth.

BRIEF RATIONALE

In this nationwide study, we suggest that rehabilitation for long-term hospitalized patients with threatened preterm birth may reduce the risk of preterm birth.