Effects of physical activity during pregnancy on preterm delivery and mode of delivery: The Japan Environment and Children's Study, birth cohort study

The single-cell immune profile throughout gestation and its potential value for identifying women at risk for spontaneous preterm birth

Precisely timed immune adaptations, observed in the maternal circulation, underpin the notion of an immune clock of human pregnancy that supports its successful progression and completion at delivery. This immune clock is divided into three immunological phases, with the first phase starting at the time of conception and implantation, shifting into the second phase that supports homeostasis and tolerance throughout pregnancy, and culminating in the last phase of labor and parturition. Disruptions of this immune clock are reported in pregnancy complications such as spontaneous preterm birth. However, our understanding of the immune clock preceding spontaneous preterm birth remains scattered. In this review, we describe the chronology of maternal immune cell adaptations during healthy pregnancies and highlight its disruption in spontaneous preterm birth. With a focus on single-cell cytometric, proteomic and transcriptomic approaches, we review recent studies of term and spontaneous preterm pregnancies and discuss the need for future prospective studies aimed at tracking pregnancies longitudinally on a multi-omic scale. Such studies will be critical in determining whether spontaneous preterm pregnancies progress at an accelerated pace or follow a preterm-intrinsic pattern when compared to those delivered at term.

Adherence to Healthy Prepregnancy Lifestyle and Risk of Adverse Pregnancy Outcomes: A Prospective Cohort Study

OBJECTIVE

To quantify the association between a combination of modifiable prepregnancy lifestyle factors and the risk of adverse pregnancy outcomes (APOs).

DESIGN

Prospective cohort study.

SETTING

The Japan Environment and Children's Study.

POPULATION

A total of 79 703 pregnant Japanese women without chronic disease.

METHODS

Maternal lifestyle before pregnancy was assessed using a self-administered questionnaire. A healthy lifestyle score (HLS, 0-5 points) was calculated based on adherence to five prepregnancy healthy lifestyle factors: healthy weight, high-quality diet, regular physical activity, not smoking, and not drinking alcohol. Relative risks (RRs) and 95% credible intervals (CrIs) were estimated using a Bayesian log-binomial regression model.

MAIN OUTCOME MEASURES

Composite APOs, defined as the development of any APO, including gestational diabetes, hypertensive disorders of pregnancy, preterm birth, low birth weight, and small-for-gestational-age, transcribed from medical records.

RESULTS

A total of 13 894 women (17.4%) experienced one or more APOs. HLS was inversely associated with the risk of APOs in a dose-response manner. Women with an HLS of 5 points had a 33% (RR 0.67; 95% CrI, 0.61-0.74) lower risk of APOs than those with the lowest HLS (0-1 points). The population attributable fraction of five healthy lifestyle factors was 10.3%. A 1-point increase of HLS could have reduced APO cases by 6.6%.

CONCLUSIONS

A higher HLS was associated with a lower risk of APOs, suggesting that adopting a healthy lifestyle before pregnancy may reduce the risk of APOs, which can increase the risk of future chronic diseases in both mother and child.

Determinants of Adverse Perinatal Outcomes in Ibadan, Nigeria: The influence of maternal lifestyle

Adverse perinatal outcomes (APO) are unfavourable incidents of at least one of the following: low birth weight, preterm delivery, stillbirths, neonatal deaths, and perinatal deaths. They contribute significantly to neonatal and infant morbidity and mortality, developmental abnormalities, and long-term impairments. Studies are lacking on the influence of maternal lifestyle on APO in Nigeria. Hence, we investigated the determinants of APO using the Ibadan Pregnancy Cohort Study (IbPCS) data and examined 1,339 mothers who had hospital delivery. The outcome variable was APO (low birth weight, birth asphyxia and preterm delivery). Explanatory variables comprised Antepartum Depression (Edinburgh Depression Scale ≥ 12), Physical activity (Pregnancy Physical Activity Questionnaire (PPAQ), Dietary pattern (Qualitative Food Frequency Questionnaire (FFQ), Maternal Stress (Perceived Stress Scale), Alcohol consumption, and Tobacco exposure. We used binary and multiple logistic regression to assess the associations between the risk factors and adverse perinatal outcomes at a significant P-value <0.05. Prevalence of APO was 26.7%, 95%CI (24.4-29.1); low birth weight - 8.5%, 95%CI (7.0-10.1) preterm delivery 14.8%, 95% CI (12.9-16.7); birth asphyxia 16.3%, 95%CI (14.0-18.9). The factors associated with LBW were being a female infant AOR: 2.00, 95%CI (1.13 -3.52); emergency caesarean section AOR: 2.40, 95%CI (1.06-5.42); a history of hypertension in pregnancy AOR: 3.34, 95%CI (1.45 -7.52). Preterm birth was associated with being poor AOR: 2.00, 95%CI (1.13 -3.52); history of stillbirth AOR: 2.05, 95%CI (1.14-3.68); antepartum depression AOR: 1.87, 95%CI (1.08-3.25). Of the lifestyle factors examined, only a high protein diet with a non-alcoholic beverage dietary pattern had a statistically significant association with preterm birth [AOR: 0.50, 95%CI (1.08-3.52)]. However, lifestyle factors had no significant association with LBW and birth asphyxia in our study. Understanding these risk factors can help policymakers and healthcare professionals create cost-effective interventions to curtail the burden of APO in Nigeria.

Exercise during pregnancy Dose: Influence on preterm birth outcomes

BACKGROUND

Preterm delivery typically increases health risk for neonates and is associated with longer infant hospital stay and financial burden. Prenatal exercise dose (frequency, intensity, type, time, volume) have been shown to influence birth outcomes. Increased prenatal exercise dose could therefore provide a critical reduction in health risk and financial burden in preterm neonates.

OBJECTIVE

It was our aim to explore the effects of prenatal exercise dose from a supervised exercise intervention in pregnant women on the occurrence of preterm (<37 weeks gestation) births, and the impact on health outcomes in preterm neonates.

STUDY DESIGN

This study is a retrospective, secondary analysis of pooled data from three blinded, prospective, randomized controlled trials. Prenatal exercise dose were assessed in supervised aerobic, resistance, and combination sessions throughout pregnancy. In addition to gestational age, birth weight, resting heart rate, neonatal morphometrics (body circumferences, ponderal index), and health status (Apgar-1 and -5) metrics were obtained for 21 women at birth. One-way analysis of variance tests were used to assess the differences between dose grouped as tertiles, while Pearson correlations determined the association between dose and birth outcomes.

RESULTS

Women exercised for an average of 19.6 wks (range: 6 - 21 wks) during pregnancy. Exercise during pregnancy tended to result in later preterm deliveries (p = 0.08). Greater prenatal exercise volume and duration were associated with reduced infant hospital stay post-delivery (p = 0.02). Weekly exercise volume was associated with increased Apgar scores (p = 0.01).

CONCLUSION

Increased prenatal exercise volume and duration is associated with improved birth outcomes in preterm neonates.

Recent Findings on Exercise Therapy for Blood Glucose Management in Patients with Gestational Diabetes

Inadequate management of blood glucose levels in gestational diabetes mellitus (GDM) poses risks for both pregnant women and the developing fetus. Attaining appropriate blood glucose control is crucial to mitigate potential adverse outcomes. This study aimed to consolidate the latest guidelines from representative professional societies, providing insights into exercise therapy for GDM patients and suggesting potential avenues for future research. The review was conducted with up-to-date exercise guidelines from prominent societies, such as the American College of Obstetricians and Gynecologists (ACOG), the Society of Obstetricians and Gynecologists of Canada (SOGC), the Canadian Society for Exercise Physiology (CSEP), the American College of Sports Medicine, the American Diabetes Association (ADA), and the Korean Diabetes Association. The ACOG and SOGC/CSEP recommend 150 min of low to moderate intensity exercise, 3-4 times a week, combining aerobic and resistance exercises. All guidelines advise against activities involving sudden directional changes, physical contact, a risk of falling, and exercises performed lying down. Despite cautions from the ADA and ACOG on blood glucose fluctuations during physical activity, the lack of specific methods and recommendations from other societies reveals a notable gap in evidence-based guidelines for GDM. For effective and safe blood glucose management in GDM patients, further research should be conducted on the exercise-related precautions outlined for GDM patients. Establishing ample evidence would facilitate the development of customized exercise guidelines for GDM patients.

Gestational Age and Neurodevelopmental Delay in Term Births at 6 and 12 Months: The Japan Environment and Children's Study (JECS)

BACKGROUND

In the recent years, a high risk of developmental delay not only in very low birth weight infants and late preterm infants but also in early term infants (37-38 weeks) have increasingly been reported. However, in Japan, there are virtually no studies regarding the development delays in early term infants.

METHODS

This study used the data from the Japan Environment and Children's Study (JECS), a birth cohort study conducted in Japan. Data were selected for analysis from the records of 104,065 fetal records. The risk of neurodevelopmental delays at 6 months and 12 months after birth was evaluated using multivariate analysis for infants of various gestational ages, using the 40th week of pregnancy as a reference value. Neurodevelopment was evaluated at 6 months and 12 months after birth using the Ages and Stages Questionnaires, Japanese translation (J-ASQ-3).

RESULTS

The proportion of infants born at a gestational age of 37 to 38 weeks who did not reach the J-ASQ-3 score cutoff value was significantly higher in all areas at both 6 months and 12 months after birth, when compared to that of infants born at 40 weeks. The odds ratio decreased at 12 months after birth compared to that at 6 months after birth.

CONCLUSION

Early term infants in Japan are at an increased risk of neurodevelopmental delay at 12 months after birth.

Exercise FITT-V during pregnancy: Association with birth outcomes

BACKGROUND

Prenatal exercise improves birth outcomes, but research into exercise dose-response effects is limited.

METHODS

This study is a retrospective, secondary analysis of pooled data from three blinded, prospective, randomized controlled trials. Prenatal exercise frequency, intensity, type, time, and volume (FITT-V) were assessed in supervised sessions throughout pregnancy. Gestational age (GA), neonatal resting heart rate (rHR), morphometrics (body circumferences, weight-to-length and ponderal index) Apgar and reflex scores, and placental measures were obtained at birth. Stepwise regressions and Pearson correlations determined associations between FITT-V and birth outcomes.

RESULTS

Prenatal exercise frequency reduces ponderal index (R2 = 0.15, F = 2.76, p = .05) and increased total number of reflexes present at birth (R2 = 0.24, F = 7.89, p < .001), while exercise intensity was related to greater gestational age and birth length (R2 = 0.08, F = 3.14; R2 = 0.12, F = 3.86, respectively; both p = .04); exercise weekly volume was associated with shorter hospital stay (R2 = 0.24, F = 4.73, p = .01). Furthermore, exercise type was associated with placenta size (R2 = 0.47, F = 3.51, p = .01).

CONCLUSIONS

Prenatal exercise is positively related to birth and placental outcomes in a dose-dependent manner.

The association between musculoskeletal pain during pregnancy and pregnancy outcomes: A systematic review and meta-analyses

OBJECTIVE

To systematically investigate the association between musculoskeletal pain during pregnancy and birth outcomes including caesarean section, newborn birthweight, newborn birth length, and gestational age at birth.

METHODS

Medline, Embase, Web of Science, Cinahl and Scopus were systematically searched to identify eligible studies. Odds ratios, mean differences, and confidence intervals were used to describe results. Risk of Bias was assessed using the Newcastle-Ottawa Scale for observational studies. GRADE (The Grading of Recommendation Assessment, Development, and Evaluation) was used to assess the quality of each outcome.

RESULTS

Seven studies were included with a total population of 85,991 participants. There is low- quality evidence that pregnant women with musculoskeletal pain had 1.59 greater odds to experience delivery by caesarean section compared to those without musculoskeletal pain ([OR] 1.59, 95 % confidence interval [CI] 1.09 to 2.31). Both newborn birth weight (Mean Difference [MD] 77.79 g, 95 % [CI] -23.09 to 178.67) and newborn birth length ([MD] 0.55 cm, 95 % [CI] -0.47 to 1.56) were not affected by musculoskeletal pain, with very low-quality and low-quality evidence, respectively. There was moderate evidence that pregnant women with musculoskeletal pain had shorter gestational age (weeks), although the effect was small and possibly not clinically relevant ([MD] -0.41, 95 % [CI] -0.41 to -0.07).

CONCLUSION

Pregnant women experiencing musculoskeletal pain are at greater odds of delivering their babies via caesarean than those without musculoskeletal pain, however, musculoskeletal pain during pregnancy does not appear to affect newborn birth weight, length, or gestational age at birth.

Investigating the association of the lifestyle of pregnant women with the rate of preterm labor

Introduction

From a long time ago, preterm birth has posed life-threatening risks due to the significant complications it causes. The present study aimed to examine how the lifestyle of pregnant women is related to the incidence of preterm birth.

Materials and Methods

For this cohort study, a total of 234 individuals with healthy and unhealthy lifestyles who visited the women's clinics of Azad University hospitals during the year 2021 were randomly selected to participate. Four criteria were utilized to build lifestyle questionnaires, which included smoking habits, physical activity levels, consumption of high-fiber foods, and sufficient sleep. According to the individuals' responses, 117 mothers who scored above 14, and 117 mothers who scored below 14 were followed up. The SPSS version 25 (SPSS Inc., Chicago, Ill., USA) was used to analyze the correlation between variables and preterm birth, employing statistical tests such as Mann-Whitney, Chi-square, and independent t-test.

Results

In this study, the mean age of the examined women was 27.11 ± 3.19. Out of the total number of babies, 133 (56.8%) were females, while 101 (43.2%) were males. The P value for the association between lifestyle and preterm birth was less than 0.0001, indicating statistical significance. The difference between the consumption of tobacco, fruits, and vegetables and sufficient sleep with preterm birth was not statistically significant (P value >0.05).

Conclusion

A healthy lifestyle can serve as an important preventive measure against preterm birth. Adequate education provided by the healthcare and treatment system plays an important role in promoting the adoption of a healthy lifestyle and benefiting from its positive outcomes.

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.

A narrative review of exercise dose during pregnancy

The current recommendations for prenatal exercise dose align with those from the American College of Sports Medicine; 150 min of moderate intensity every week of pregnancy. However, recent works suggest there may be a dose-dependent beneficial effect for mother and offspring; maternal and offspring health outcomes respond differently to low, medium, and high doses of prenatal exercise. It is, therefore, our aim to summarize the published evidence (years 1950-2023) for five metrics of prenatal exercise training commonly reported, that is, "FITT-V": Frequency (number of sessions), Intensity (metabolic equivalents "METs"), Time (duration of sessions), Type (exercise mode), Volume (exercise MET*mins). The target audience includes clinicians and health care professionals, as well as exercise professionals and physiologists. Data suggest that moderate exercise frequency (3-4 times weekly) appears safe and efficacious for mother and offspring, while there is contradictory evidence for the safety and further benefit of increased frequency beyond 5 sessions per week. Moderate (3-6 METs) and vigorous (>6 METs) intensity prenatal exercise have been shown to promote maternal and offspring health, while little research has been performed on low-intensity (<3 METs) exercise. Exercise sessions lasting less than 1 hr are safe for mother and fetus, while longer-duration exercise should be carefully considered and monitored. Taken together, aerobic, resistance, or a combination of exercise types is well tolerated at medium-to-high volumes and offers a variety of type-specific benefits. Still, research is needed to define (1) the "minimum" effective dose of exercise for mother and offspring health, as well as (2) the maximum tolerable dose from which more benefits may be seen. Additionally, there is a lack of randomized controlled trials addressing exercise doses during the three trimesters of pregnancy. Further, the protocols adopted in research studies should be more standardized and tested for efficacy in different populations of gravid women.

Do pregnant African women exercise? A meta-analysis

INTRODUCTION

Antenatal exercise can reduce gestational weight gain, backache; pregnancy induced medical disorders, caesarean section rates, and improves pregnancy outcomes. American College of Obstetrics and Gynecology (ACOG) recommends prenatal exercise, which is associated with minimal risk and has been shown to be beneficial for pregnancy outcomes, although some exercise routines may need to be modified. Consequently, this meta-analysis is intended to verify the pooled practice of antenatal exercise in Africa using available primary articles.

METHODS

Genuine search of the research articles was done via PubMed, Scopes, Cochrane library, the Web of Science; free Google databases search engines, Google Scholar, and Science Direct databases. Published and unpublished articles were searched and screened for inclusion in the final analysis and Studies without sound methodologies, and review and meta-analysis were not included in this analysis. The Newcastle-Ottawa scale was used to assess the risk of bias. If heterogeneity exceeded 40%, the random effect method was used; otherwise, the fixed-effect method was used. Meta-analysis was conducted using STATA version 14.0 software. Publication bias was checked by funnel plot and Egger test.

RESULTS

This review analyzed data from 2880 women on antenatal care contact from different primary studies. The overall pooled effect estimate of antenatal exercise in Africa was 34.50(32.63-36.37). In the subgroup analysis for pooled antenatal exercise practice by country, it was 34.24 (31.41-37.08) in Ethiopia and 37.64(34.63-40.65) in Nigeria.

CONCLUSION

The overall pooled effect estimate of antenatal exercise in Africa was low compared to other continent. As it was recommended by ACOG antenatal exercise to every patient in the absence of contraindications, it should be encouraged by professionals providing antenatal care service.

Determination of Pregnant Women's Physical Activity and Exercise Status During Pregnancy and Affecting Factors

Objective: This study aims to determine pregnant women's physical activity and exercise status during pregnancy and affecting factors. Methods: The research was conducted in a cross-sectional design with 220 low-risk pregnant women who were in their third trimester between March 3 and June 29 2022 at Training and Research Hospital. Research data were collected by face-to-face interview method using the forms developed by the authors. Results: It was seen that among the pregnant women who participated in the research, 35.9% exercised regularly before pregnancy and 25.9% regularly exercised during pregnancy. The most common exercises performed during pregnancy were walking and pilates. The assessment of the physical activity of pregnant women revealed that 80.5% were sedentary. The rate of exercising during pregnancy was 4.04 times (aOR 4.04, 95% CI 1.33-12.27) higher in women with planned pregnancies compared to unplanned pregnancies and 30.57 times higher in women who exercised regularly before pregnancy compared to those who did not do so (aOR 30.57, 95% CI 12.53-74.55). Likewise, compared to those who were obese during pregnancy, non-obese ones were 0.36 times more physically active (aOR 0.36, 95% CI 0.16-0.84). Similarly, it was established that women who exercised before pregnancy were 10.51 times more physically active than those who did not (aOR 10.51, 95% CI 4.60-24.02). Conclusion: In the research, it was concluded that the rates of exercising and being physically active during pregnancy were low, that planned pregnancy and regular exercise before pregnancy increased exercise behavior during pregnancy, and that obesity decreases physical activity.

Association between maternal fish consumption during pregnancy and preterm births: the Japan Environment and Children's Study

BACKGROUND

Fish are a rich source of essential nutrients that protect against preterm birth. However, as fish can absorb environmental pollutants, their consumption can also increase the risk of preterm birth. This study aimed to assess whether maternal fish consumption during pregnancy is associated with preterm birth in a nationwide large Japanese cohort that consumed relatively high amounts and many types of fish.

METHODS

This study included 81,428 mother-child pairs enrolled in a nationwide prospective Japanese birth cohort study. Fish consumption was assessed using a validated food frequency questionnaire. Multivariate logistic regression was used to investigate the association of total consumption of fish, fatty fish and lean fish, fish paste, and seafood and clams with preterm birth, adjusted for potential confounders.

RESULTS

There was no association between overall fish consumption and preterm births. However, the highest quintile of fish paste consumption was significantly associated with an increased risk of preterm birth (odds ratio [OR]: 1.11; 95% confidence interval [CI: 1.04, 1.17]). The consumption of baked fish paste at least three times per week was significantly associated with preterm birth (OR: 1.20; 95% CI: 1.03, 1.40). Consumption of other types of fish, except fish paste, was not significantly associated with preterm birth risk.

CONCLUSIONS

Fish paste consumption may increase the risk of preterm birth. Further studies are required to confirm this association.

Subjective well-being, happiness, and environmental health factors related to women planning a pregnancy or pregnant, using mobile health intervention

Objectives

To compare the environmental health results in women trying to get pregnant or pregnant using a mobile health application (Green Page) through healthcare professionals or self-completed by women, and to explore the relationship between the subjective well-being of these women with their lifestyles and environmental factors.

Methods

A descriptive study with mixed methods was conducted in 2018. A mobile health survey was used in two phases. Phase 1 was a cross-sectional study through professionals (n  =  1100) followed by phase 2, a convenience sampling through women's self-reporting (n  =  3425). A personalized report was downloadable with health recommendations for the well-being of the mother and child.

Results

Of the 3205 participants (mean age  =  33 years, SD  =  0.2 years), 1840 were planning a pregnancy and 1365 were pregnant. One in five pregnant women had a low level of happiness. Globally, subjective well-being and happiness were found to be negatively associated with lack of contact with nature, sedentary lifestyle, excess weight, environmental exposure, and older age in pregnancy. Precisely 45%, 60%, and 14% of women were exposed to tobacco, alcohol, and illegal drugs, respectively. The women self-reported levels of risk factors higher than when the tool was used by or through professionals.

Conclusions

The use of mobile health interventions focused on environmental health during planning or pregnancy periods could help improve the quality of healthcare and foster greater involvement of women in their self-care process, thus promoting empowerment, healthier environments, and lifestyles. Ensuring equity of access and data protection are global challenges to be addressed.

Surgical and obstetric outcomes of breast cancer surgery during pregnancy: a nationwide database study in Japan

PURPOSE

Although the incidence of breast cancer during pregnancy is increasing, little is known about short-term outcomes following breast cancer surgery during pregnancy. We aimed to compare the characteristics and outcomes of breast cancer surgery with and without pregnancy, and describe the obstetric outcomes following surgery.

METHODS

The data of 249,257 female patients aged < 60 years who underwent breast cancer surgery between July 2010 and March 2020 were analyzed using a nationwide Japanese database; we generated a 1:10 matched-pair cohort (260 and 2597 patients with and without pregnancy, respectively) matched according to age and treatment year. We conducted multivariable analyses to compare surgical procedures and outcomes, adjusting for potential confounders in the matched-pair cohort. Additionally, we described the obstetric outcomes of patients with pregnancy.

RESULTS

Patients with pregnancy were more likely to undergo total mastectomy [odds ratio: 1.48 (95% confidence interval: 1.13-1.94)] and axillary dissection [1.62 (1.17-2.24)], but less likely to undergo reconstruction [0.14 (0.07-0.31)], than patients without; however, postoperative complications, postoperative length of stay, and total hospitalization costs did not differ significantly with pregnancy. Additionally, some pregnant patients experienced premature delivery [n = 18 (6.9%)] and miscarriage [n = 4 (1.5%)], and 31 of 101 patients in the third trimester at breast cancer surgery underwent a cesarean section.

CONCLUSION

This study demonstrated significant differences regarding surgical procedures; however, there were no significant differences regarding surgical outcomes between patients who underwent breast cancer surgery with and without pregnancy. Obstetric outcomes following breast cancer surgery were also reported.

The Effect of Physical Activity during Pregnancy on Childbirth

Active pregnant women have fewer physical problems and gain weight during pregnancy, and this often leads to fewer complications as exercise also increases self-confidence and reduces the risk of mood swings after childbirth (postpartum) and depression, and “it is not only the women who benefits from being active.” Studies have shown that exercise during pregnancy has a “training effect” on the baby, and this is reflected in increased heart rate variability and a decrease in the fetus’s resting heart rate. Aim of this study is known Effect of Physical Activity during Pregnancy on Childbirth. 155 patients were collected from Bint Al-Huda Maternity & Children Hospital, Thi-Qar, Iraq, and the samples were divided into two groups (90 women who practiced exercise and 65 for control).  All demographic information about patients was obtained through the distribution of questionnaires, and several techniques were used to analyze the results, including the statistical analysis program in evaluating physical activity on childbirth and analyzing the effects generated during pregnancy and the duration of the stage of labor and Positive results were found in the assessment of physical activity on pregnant women, and the results were in another way related to age and body mass index.

Prospective associations between prepartum physical activity, birth experience, and maternal depressive symptoms in the postpartum period: Insights from the population-based DREAM cohort study

BACKGROUND

This study aims to examine whether physical activity (PA) before and during pregnancy and birth experience predict incident postpartum depressive (PPD) symptoms. Because PA may increase endurance and feelings of physical control, it may contribute to a positive birth experience and birth experience may mediate the association between PA before and during pregnancy and PPD symptoms.

METHODS

The study is part of the prospective-longitudinal cohort study "Dresden Study on Parenting, Work, and Mental Health" (DREAM). Participants were n = 1,254 (expectant) mothers. PA was assessed during pregnancy, birth experience and PPD symptoms 8 weeks postpartum. Multiple regression analyses were performed, including potential confounders.

RESULTS

A negative birth experience was linked to PPD symptoms, when controlling for relevant confounders. There was no evidence for a link between PA before and during pregnancy and birth experience or between PA during pregnancy and PPD symptoms. PA at low and at vigorous intensity before pregnancy was associated with PPD symptoms, but not when controlling for confounders. Because PA was not associated with birth experience, no mediation analysis was performed.

LIMITATIONS

The current sample was relatively homogenous (i.e., mostly German native speakers, primiparous, highly educated). Birth experience was assessed retrospectively at 8 weeks following birth.

CONCLUSIONS

Our results highlight the importance of the birth experience in the development of PPD symptoms. Promoting a positive birth experience represents a promising approach to prevent PPD symptoms. Further research on the association between PA and PPD symptoms is warranted.

Relationship between Physical Activity and Physical and Mental Health Status in Pregnant Women: A Prospective Cohort Study of the Japan Environment and Children's Study

To discuss appropriate physical activity (PA) levels during pregnancy, this prospective cohort study examined the relationships between PA levels before and during pregnancy and physical and mental health status. Fixed data for 104,102 pregnant women were used from the Japan Environment and Children’s Study, of which data for 82,919 women were analyzed after excluding women with multiple birth and pregnancy complications. PA levels were measured using the International Physical Activity Questionnaire-Short Form. The 8-Item Short Form Health Survey was used to measure outcomes. Logistic regression with multiple imputations showed that moderate PA for over 720 min/wk and vigorous PA before pregnancy were associated with poorer mental health in the first trimester (adjusted odds ratio (AOR): 1.087–1.376. Walking in the second and third trimesters was associated with better physical and mental health (AOR: 0.855–0.932). Moderate PA over 1080 min/wk and vigorous PA in the second and third trimesters were associated with poorer mental health (AOR: 1.223–1.873). Increases over 4135.4 MET–min/wk and decreases in PA levels were associated with poorer mental and physical health (AOR: 1.070–1.333). Namely, pregnant women receiving health benefits prefer continuous walking in addition to avoiding vigorous PA and excessive changes in PA levels during pregnancy.

Low Back Pain during Pregnancy and Delivery Outcomes

AIM

To evaluate low back pain (LBP) incidence and impact throughout pregnancy in terms of women's well-being and delivery outcomes.

MATERIAL AND METHODS

Cross-sectional prospective study conducted on singleton pregnancies at ≥37th gestational age admitted for delivery. Localization of LBP, intensity and frequency as well as derived functional disability status were assessed with a self-reported questionnaire. Main delivery outcomes including mode of delivery, and maternal or neonatal complications were recorded.

RESULTS

A total of 229 women participated in the study. LBP prevalence amounted to 55.9%, with the pain already present before pregnancy in 14.0% of the cases. The pain was mostly localized in the lower back (40.6%), symphysis (23.3%), and coccyx (20.5%). Both the frequency and intensity of pain gradually increased significantly during pregnancy, reaching 20 days/month (IQR=10-30) and 6/10 points (IQR=5-8) on a visual analog scale in the 3rd trimester (p<0.05). The extent of functional impairment also progressively increased up to 39/100 points (IQR=25-55, p<0.05). Women affected by LBP during pregnancy had a higher cesarean section rate during labor than women without LBP (11.9% vs. 28.9%, p<0.05). The risk was also significant in the multivariate analysis (OR=4.0, 95%CI=1.1-15.0, p<0.05). There was no difference in the rate of operative vaginal births or in the other outcomes considered.

CONCLUSIONS

LBP is a common issue in pregnant women, accounting for increasing morbidity and invalidity, and leading to an increased cesarean section risk during labor.

Preterm birth and PM2.5 in Puerto Rico: evidence from the PROTECT birth cohort

BACKGROUND

Preterm birth (PTB, birth before 37 weeks of gestation) has been associated with adverse health outcomes across the lifespan. Evidence on the association between PTB and prenatal exposure to air pollutants is inconsistent, and is especially lacking for ethnic/racial minority populations.

METHODS

We obtained data on maternal characteristics and behaviors and PTB and other birth outcomes for women participating in the Puerto Rico Testsite for Exploring Contamination Threats (PROTECT) cohort, who lived in municipalities located along the North Coast of Puerto Rico. We assessed pre-natal PM_2.5 exposures for each infant based on the nearest US Environmental Protection Agency monitor. We estimated prenatal phthalate exposures as the geometric mean of urinary measurements obtained during pregnancy. We then examined the association between PM_2.5 and PTB using modified Poisson regression and assessed modification of the association by phthalate exposure levels and sociodemographic factors such as maternal age and infant gender.

RESULTS

Among 1092 singleton births, 9.1% of infants were born preterm and 92.9% of mothers had at least a high school education. Mothers had a mean (standard deviation) age of 26.9 (5.5) years and a median (range) of 2.0 (1.0-8.0) pregnancies. Nearly all women were Hispanic white, black, or mixed race. Median (range) prenatal PM_2.5 concentrations were 6.0 (3.1-19.8) μ g/m³. Median (interquartile range) prenatal phthalate levels were 14.9 (8.9-26.0) and 14.5 (8.4-26.0), respectively, for di-n-butyl phthalate (DBP) and di-isobutyl phthalate (DiBP). An interquartile range increase in PM_2.5 was associated with a 1.2% (95% CI 0.4, 2.1%) higher risk of PTB. There was little difference in PTB risk in strata of infant sex, mother's age, family income, history of adverse birth outcome, parity, and pre-pregnancy body mass index. Pregnancy urinary phthalate metabolite levels did not modify the PM_2.5-PTB association.

CONCLUSION

Among ethnic minority women in Puerto Rico, prenatal PM_2.5 exposure is associated with a small but significant increase in risk of PTB.

Physical activity and sleep duration during pregnancy have interactive effects on caesarean delivery: a population-based cohort study in Tianjin, China

Background

There were inconsistent findings in the literature regarding the associations of physical activity and sleep duration during pregnancy with caesarean delivery for different reasons. It was also unknown whether physical activity and sleep duration during pregnancy had interactive effects on the risks of different types of caesarean delivery. The study aimed to investigate the effects of physical activity, sleep duration and their interactions on the risk of caesarean delivery for medical reasons and non-medical reasons.

Methods

From October 2010 to August 2012, a prospective population-based cohort of 13,015 pregnant women was established in six central urban districts of Tianjin, China. Pregnancy outcomes were retrieved from an electronic database and caesarean delivery was divided into caesarean delivery for medical reasons and caesarean delivery for non-medical reasons. Physical activity and sleep status were collected at 24–28 weeks of gestation using self-reported questionnaires. Logistic regression and additive interaction were used to examine physical activity, sleep duration and their interactive effects on risk of caesarean delivery.

Results

In the cohort, 5692 (43.7%) and 2641 (20.3%) of women had caesarean delivery for medical reasons and non-medical reasons, respectively. Low physical activity increased the risk of caesarean delivery for medical reasons (adjusted OR: 1.13, 95%CI 1.04–1.23) but not caesarean delivery for non-medical reasons. Sleep duration < 7 h/day and poor sleep quality were not associated with caesarean delivery. Sleep duration ≥9 h/day increased the risk of caesarean delivery for medical reasons (1.12, 1.02–1.22) and caesarean delivery for non-medical reasons (1.16, 1.05–1.29). Co-presence of low physical activity and sleep duration ≥9 h/day increased risk of caesarean delivery (1.25, 1.12–1.41), and their additive interaction was statistically significant for caesarean delivery for medical reasons but not for caesarean delivery for non-medical reasons.

Conclusions

Low physical activity and excessive sleep duration during pregnancy each increased the risk of caesarean delivery, and they had an interactive effect on the risk of caesarean delivery for medical reasons but not on the risk of caesarean delivery for non-medical reasons. Increasing physical activity and maintaining recommended sleep duration during pregnancy may have benefits for perinatal health.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03788-4.

Physical Activity in Pregnancy: Beliefs, Benefits, and Information-Seeking Practices of Pregnant Women in South Africa

Background

Notwithstanding the benefits of physical activity (PA) during pregnancy, anecdotal evidence suggests ignorance, unscientific beliefs, and lack of awareness about PA among pregnant South African women.

Aim

This study examined the beliefs, perceived benefits, and sources of information on PA during pregnancy.

Methods

A cross-sectional descriptive study was employed between June and September 2019 using an interviewer-administered questionnaire with 1,082 pregnant women. These women were attending antenatal primary health–care clinics in Buffalo City, Eastern Cape, South Africa. A self-designed questionnaire solicited information on beliefs, benefits, and sources of information regarding PA during pregnancy.

Results

A majority of the participants held positive beliefs concerning PA during pregnancy. They maintained that PA was safe for mother and fetus, improved labor and delivery (93.1%), promoted energy (89.0%), and should be discontinued when tired (76.6%). Most held negative convictions that PA during pregnancy increased body temperature (64.5%) and that pregnancy was a time to rest and refrain from PA (56.5%). Predominantl sources of information received about PA during pregnancy were television, the radio, and other media (70.2%). Most participants were aware of the benefits of PA during pregnancy —— reduction in infant weight (61.4%), lessening of moodiness (90.4), and decreased risk of gestational diabetes mellitus (92.9%), pregnancy-induced hypertension (92.5%), and complications at birth (97.8%), while common negative perceptions included musculoskeletal discomfort (82.7%), and back pain (85.7%). An overwhelming majority affirmed that PA improved self-image (95.7%), sleep patterns (94.2%), and respiratory function (95.8%).

Conclusion

Our findings suggested that women hold positive beliefs and perceive PA as beneficial to their health and the baby; however, they received most of their information from the Internet. Most women regarded pregnancy as a period to relax and rest. Interventions to promote PA during pregnancy are needed.

Exercise Counseling in Pregnancy: Do Women Perceive Receiving the Information They Need?

The American College of Obstetricians and Gynecologists recommends that women exercise throughout pregnancy unless they have a condition-related contraindication. This study's purpose was to determine if pregnant women perceive receiving exercise counseling by their providers with details of frequency, intensity, type, and time (FITT principle). Women in 2 postpartum care units of a large health care system were invited to complete a voluntary, anonymous survey regarding whether they received exercise counseling during their prenatal care. Survey results were descriptively reported, stratified by demographic variables, and analyzed using Fisher's exact tests. Of 224 postpartum women surveyed, 130 (58.0%) perceived receiving exercise counseling during pregnancy; 119 (91.5%) did not recall receiving counseling on exercise frequency. Though 165 (73.6%) exercised before becoming pregnant, 64 (38.8%) ceased exercise during pregnancy. Eighty-eight (39.3%) received advice from other sources/non-health care professionals. Privately insured women reported receiving exercise counseling at a higher rate (70.1%) than those on Medicaid (44.8%) or uninsured (40.0%; P = .004). A disproportionate number of pregnant women perceived not receiving adequate prenatal exercise counseling or received incomplete counseling. Women at a socioeconomic disadvantage may be vulnerable. As social determinants of health, structural barriers, and socioeconomic status likely contribute, women may benefit from more targeted inclusive and equitable messaging.

Physical activity and exercise during pregnancy in Africa: a review of the literature

BACKGROUND

Pregnancy is an important phase in a woman's life, with health status at this stage affecting both the woman and her child's life. Global evidence suggests that many women engage in low levels of physical activity (PA) and exercise during pregnancy despite its beneficial effects. This is particularly the case in Africa.

METHODS

This article reviews the literature on levels of PA and exercise among pregnant women in Africa, highlighting the level of PA or exercise participation during pregnancy in Africa, including types of PA, factors affecting PA, beliefs about and benefits of prenatal activity, advice or counselling on PA during pregnancy in Africa, and PA interventions proposed to promote the uptake of prenatal PA. Electronic search databases used were Google Scholar, Science Direct, Scopus, EMBASE, ERIC, Medline, Web of Science, EBSCOhost, PubMed, BIOMED Central, and African Journal Online. The basic search terms were: 'Physical activity', 'Exercise', 'Pregnancy', 'Pregnant women' and 'Africa'. A total of 40 references were found. On the basis of an analysis of titles, abstracts and the language of publication (other than English), 11 articles were rejected, and 29 articles were fully read, although two had to be rejected due to a lack of access to the full version. Finally, 27 references were included in the review.

RESULTS

Few studies exist on PA during pregnancy in Africa. The limited data available suggests that, compared to the Western world, pregnant women in Africa do not adhere to the recommendations for PA during pregnancy. Levels of participation in PA during pregnancy are low and decline as the pregnancy progresses. The majority of the studies used direct, objective measures to assess PA during pregnancy. Personal and environmental factors such as lack of time, lack of knowledge, inadequate information from healthcare providers, feelings of tiredness and an absence of social support constituted the main barriers to PA during pregnancy. The types of PA participation among pregnant women varied across studies and geographical settings.

CONCLUSIONS

While published data is limited, it seems clear that the participation of pregnant women in PA during pregnancy in Africa is low and declines with advancing pregnancy. There is a need for more studies to examine the dynamics of PA during pregnancy in Africa to guide contextual interventions to improve and promote maternal health on the continent.

Developing a Physical Activity Intervention Strategy for Pregnant Women in Buffalo City Municipality, South Africa: A Study Protocol

Despite global awareness about the importance and health benefits of physical activity (PA) during pregnancy, several studies have reported a low prevalence of PA participation among pregnant women in both developed and developing countries. This means that most pregnant women do not meet the current PA recommended guideline of 150 min of moderate intensity PA per week. The global call to prioritise PA participation levels in the general population necessitates evaluating the factors affecting PA practice. Seemingly, pregnant women mostly from low-to-middle income countries like South Africa are often predisposed to adverse pregnancy outcomes, possibly because of limited access to, and knowledge of, improved pregnancy and health outcomes as a result of PA participation. Physical activity has been sparsely studied among pregnant South African women, and specifically, there is no known study that assesses the PA levels, patterns, beliefs, sources of information, perceived benefits, barriers, attitudes of pregnant women concerning PA and exercise participation; nor one that explores the perspectives of healthcare providers regarding prenatal PA in the Eastern Cape Province. In addition, no PA intervention strategy exists to promote PA participation in the region. This study, in attempting to fill these gaps in knowledge, adopts two phases. In Phase I, a concurrent mixed-method (quantitative and qualitative) approach assesses the following factors related to PA participation in pregnant women: participation levels, beliefs, attitudes, perceived benefits, barriers to uptake and sources of information. It further ascertains if healthcare professionals are sufficiently informed about PA and if they are advising pregnant women about the need for PA participation during pregnancy. Data will be collected through a structured questionnaire, interviews and focus group discussions. Information on socio-demographic and maternal characteristics will be obtained, and the Pregnancy Physical Activity Questionnaire (PPAQ) will assess PA during pregnancy. A sample size of 384 pregnant women is the required minimum sample for an infinite population at a confidence level of 95%, a precision level of ± 5% and at a prevalence of PA or exercise during pregnancy of 50% (p < 0.05); however, a sample size larger than the minimum number necessary will be recruited to account for possible attrition and to protect against possible data loss. Data will be analysed using a multiple logistic regression to determine the factors that predict sedentary or moderate PA levels and chi-squared analysis to determine the associations between the PA levels of the participants and socio-demographic and clinical variables. The study will assess the data collected on the above-mentioned variables and draw conclusions based on patterns and themes that emerge during analysis. Phase II of the study focuses on strategy development and validation to facilitate the promotion of PA during pregnancy. The developed strategy will be validated through the application of the Delphi technique and the administration of a checklist to selected key stakeholders through organised workshops. Understanding the level and correlates of PA participation among this special population is fundamental to designing intervention strategies to enhance their understanding of, and participation in, PA and exercise. Furthermore, this study's findings will inform facility-based healthcare providers about the need to integrate health education on PA and pregnancy into antenatal and postnatal care visits in the setting.

Pregnancy in GNE myopathy patients: a nationwide repository survey in Japan

BACKGROUND

GNE myopathy is an autosomal recessive adult-onset distal myopathy. While a few case reports have described the progression of GNE myopathy during pregnancy, to our knowledge, none have examined disease progression after delivery or obstetric complications.

OBJECTIVE

This study aimed to reveal maternal complications, newborn complications, and the impact of pregnancy on disease progression in GNE myopathy patients.

METHODS

We conducted a questionnaire survey on pregnancy, delivery, and newborns involving female GNE myopathy patients who are currently registered in a national registry in Japan.

RESULTS

The response rate for the questionnaire survey was 60.0% (72/120). Of the 72 respondents, 44 (61.1%) had pregnancy experience (average, 1.8 pregnancies; 53 pregnancies before onset and 28 after onset). The incidence of threatened abortion was 26.9% among post-onset pregnancies, which was higher compared to those of the general Japanese population (p = 0.03). No other maternal or infant complications were commonly observed. Over 80% were unaware of changes in disease progression during pregnancy (mean age, 32.8 ± 3.5 years) or after delivery (32.9 ± 3.8 years), while 19.0% experienced disease exacerbation within a year after delivery (30.0 ± 1.0 years). Six patients developed myopathy within a year after delivery (29.7 ± 4.6 years), while none developed myopathy during pregnancy.

CONCLUSIONS

There were no serious maternal or newborn complications, and subjective progression did not differ during or after delivery in the majority of GNE myopathy patients. However, our findings suggest the importance of considering the possibility of threatened abortion and disease progression after delivery.

Testing the Multiple Pathways of Residential Greenness to Pregnancy Outcomes Model in a Sample of Pregnant Women in the Metropolitan Area of Donostia-San Sebastián

Residential greenness may positively impact diverse human health indicators through the reduction of air pollution, the improvement of psychological health, and the promotion of physical activity. Previous studies indicate a weak but positive association with pregnancy outcomes. Our aim was to test the multiple pathways from residential greenness to pregnancy outcomes model, using residential NO₂ concentrations, psychological health, and moderate-to-vigorous physical activity (MVPA) during the first trimester of pregnancy, in a sample of 440 pregnant women residing in Donostia, Spain. Three metrics of residential greenness were calculated around each participant’s home address: normalized difference vegetation index (NDVI) within 300 m, and green space (>5000 m²) availability within 300 and 500 m. Residential NO₂ concentrations, psychological health, and MVPA were explored as mediators of the associations between these metrics and the following pregnancy outcomes: birth weight (BW), low birth weight (LBW), prematurity, small for gestational age (SGA), and large for gestational age (LGA). Educational attainment, parity, and body mass index (BMI) were treated as covariates. Counterfactual mediation analyses showed very low to null statistical support for an association between any of the greenspace metrics and pregnancy outcomes in the full sample. Green space availability (300 m) was associated with lower BW and showed a marginal protective effect against LGA.

What Accounts for Physical Activity during Pregnancy? A Study on the Sociodemographic Predictors of Self-Reported and Objectively Assessed Physical Activity during the 1st and 2nd Trimesters of Pregnancy

Physical activity (PA) during pregnancy has positive health implications for both mother and child. However, current literature indicates that not all pregnant women meet the international recommendations for PA (at least 150 min/week of moderate-to-vigorous PA). The main objective of this study was to assess PA levels among pregnant women in the city of Donostia-San Sebastian and identify their main sociodemographic predictors. We recruited 441 women in the 12th week of pregnancy from the local public obstetric health services. Women wore an accelerometer for one week during two separate time points (1st and 2nd trimesters of pregnancy) and completed a questionnaire assessing several sociodemographic variables as well as self-reported PA. With this information, we estimated women’s overall PA levels during both time points. The fulfillment of PA recommendations raised up to 77% and 85% during the first and second trimesters, respectively. We found that a higher number of children and a greater preference for exercise positively predicted light-to-moderate PA, being the most consistent predictors. The availability of a greater number of cars negatively predicted moderate-to-vigorous PA.

Physical Activity Patterns among 9000 Pregnant Women in Poland: A Cross-Sectional Study

The aim was to analyze the knowledge and experience of women regarding physical activity during their latest pregnancy. An anonymous questionnaire was completed electronically, in 2018, by 9345 women who gave birth at least once, with 52% of the women having performed exercises during pregnancy. Physically non-active respondents suffered from gestational hypertension (9.2% vs. 6.7%; p < 0.01) and gave birth prematurely (9% vs. 7%; p < 0.01) to newborns with a low birth weight significantly more often (6% vs. 3.6%; p < 0.001). Physically active women delivered vaginally more often (61% vs. 55%; p < 0.001) and were more likely to have a spontaneous onset of the delivery as compared with non-active women (73.8% vs. 70.7% p = 0.001). The women who were informed by gynaecologist about the beneficial influence of physical activity during pregnancy exercised significantly more often (67% vs. 44% p < 0.001). In addition, 13% of the women felt discrimination due to their physical activity during a pregnancy, 22% of respondents' physical activity was not accepted by their environment, and 39.1% of the women were told by others to stop physical exercise because it was bad for the baby's health. Physical activity during pregnancy is associated with improved fitness, decreased pregnancy ailments occurrence, and therefore influences the course of pregnancy and delivery in a positive way.

Factors Associated with the Leisure-Time Physical Activity (LTPA) during the First Trimester of the Pregnancy: The Cross-Sectional Study among Pregnant Women in Serbia

Background: The benefits of physical activity during pregnancy include lower maternal weight gain, a lower likelihood of gestational diabetes, low back pain, preeclampsia, preterm delivery, caesarian delivery, and macrosomia. This study aimed to examine the factors associated with insufficient leisure-time physical activity (LTPA) during the first trimester. Methods: A cross-sectional study was conducted at the Clinic for Obstetrics and Gynecology of Clinical Center of Serbia, Belgrade, between January and June of 2018. The final analyses included 162/175 pregnant women. The questionnaire was used to obtain social characteristics, pregnancy, and lifestyle characteristics (Pregnancy Risk Assessment Monitoring System-PRAMS), pre-pregnancy LTPA (International Physical Activity Questionnaire-IPAQ), and LTPA during the first trimester (Pregnancy Physical Activity Questionnaire-PPAQ). Women were classified into two groups of sufficient and insufficient LTPA during the first trimester based on the recommendations of the World Health Organization. Multivariate logistic regression analysis was applied. Results: A total of 27.2% of the women had insufficient LTPA during pregnancy. Insufficient LTPA during pregnancy was associated with <12 years of education (OR: 2.3, 95% CI: 1.05-5.04), self-rated financial status as poor (OR: 0.34, 95% CI: 0.14-0.79), and hours spent walking before pregnancy (OR: 0.87, 95% CI: 0.77-0.99). Conclusions: Our results can help direct health care professionals advice for women who are planning pregnancy towards walking as it seems to be sustained during pregnancy.

The effects of vigorous intensity exercise in the third trimester of pregnancy: a systematic review and meta-analysis

Background

Fetal growth is dependent upon utero-placental vascular supply of oxygen and nutrients from the mother and has been proposed to be compromised by vigorous intensity exercise in the third trimester. The aim of this systematic review was to investigate the effects of vigorous intensity exercise performed throughout pregnancy, on infant and maternal outcomes.

Methods

Electronic searching of the PubMed, Medline, EMBASE, Cochrane Library, Web of Science and CINAHL databases was used to conduct the search up to November 2018. Study designs included in the systematic review were randomised control trials, quasi-experimental studies, cohort studies and case-control studies. The studies were required to include an intervention or report of pregnant women performing vigorous exercise during gestation, with a comparator group of either lower intensity exercise or standard care.

Results

Ten cohort studies (n = 32,080) and five randomized control trials (n = 623) were included in the systematic review (n = 15), with 13 studies included in the meta-analysis. No significant difference existed in birthweight for infants of mothers who engaged in vigorous physical activity and those who lacked this exposure (mean difference = 8.06 g, n = 8006). Moreover, no significant increase existed in risk of small for gestational age (risk ratio = 0.15, n = 4504), risk of low birth weight (< 2500 g) (risk ratio = 0.44, n = 2454) or maternal weight gain (mean difference = − 0.46 kg, n = 1834). Women who engaged in vigorous physical activity had a small but significant increase in length of gestational age before delivery (mean difference = 0.21 weeks, n = 4281) and a small but significantly reduced risk of prematurity (risk ratio = − 0.20, n = 3025).

Conclusions

Findings from this meta-analysis indicate that vigorous intensity exercise completed into the third trimester appears to be safe for most healthy pregnancies. Further research is needed on the effects of vigorous intensity exercise in the first and second trimester, and of exercise intensity exceeding 90% of maximum heart rate.

Trial registration

PROSPERO trial registration CRD42018102109.

Electronic supplementary material

The online version of this article (10.1186/s12884-019-2441-1) contains supplementary material, which is available to authorized users.