Modify, don't stop! Time to reconsider the 'relative' and 'absolute' contraindications to physical activity in pregnancy: an opinion piece

Prenatal immobility stress: Relationship with oxidative stress, inflammation, apoptosis, and intrauterine growth restriction in rats

BACKGROUND

Prenatal stress is a significant risk factor affecting pregnant women and fetal health. In the present study, we aimed to investigate the effect of immobility stress at different periods of pregnancy on oxidative stress, inflammation, placental apoptosis and intrauterine growth retardation in rats.

METHODS

Fifty adult virgin female Wistar albino rats were used. Pregnant rats were exposed to 6 h/day immobilization stress in a wire cage at different stages of pregnancy. Groups I and II (Day 1-10 stress group) were sacrificed on the 10th day of pregnancy, and Group III, Group IV (10-19th-day stress group), and Group V (1-19th-day stress group) were sacrificed on the 19th day of pregnancy. Inflammatory cytokines, including interleukin-6 (IL-6) and interleukin-10 (IL-10), serum corticotropin-releasing hormone (CRH), and corticosterone levels were measured by enzyme-linked immunosorbent assay. Malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) levels in the placenta were spectrophotometrically measured. Histopathological analyses of the placenta were evaluated by hematoxylin and eosin staining. Tumor necrosis factor-alpha (TNF-α) and caspase-3 immunoreactivity in placenta tissues were determined by the indirect immunohistochemical method. Placental apoptosis was determined by the TUNEL staining method.

RESULTS

We found that the immobility stress during pregnancy significantly increased serum corticosterone levels. Our results showed that the immobility stress diminished the number and weight of fetuses in rats compared to the non-stress group. The immobility stress caused significant histopathological changes in the connection zone and labyrinth zone and increased placental TNF-α and caspase-3 immunoreactivity and placental apoptosis. In addition, immobility stress significantly increased the levels of pro-inflammatory IL-6 and MDA and caused a significant decrease in the levels of antioxidant enzymes such as SOD, CAT, and anti-inflammatory IL-10.

CONCLUSIONS

Our data suggest that immobility stress causes intrauterine growth retardation by activating the hypothalamic-pituitary-adrenal axis and deteriorating placental histomorphology and deregulating inflammatory and oxidative processes.

Recent Patterns of Physical Activity and Sedentary Behaviour Among Pregnant Adults in Canada

OBJECTIVE

To evaluate current levels of physical activity and sedentary behaviour among pregnant and non-pregnant adults in Canada.

METHODS

We ascertained population-based cross-sectional data from the Canadian Community Health Survey (CCHS), 2015-2019, and the Canadian Health Measures Survey (CHMS), 2007-2019. We included adults who were assigned female at birth and were of reproductive age (aged 18-55 years) living in the provinces. We analyzed activity data from validated questionnaires and accelerometers.

RESULTS

We included 53 765 adults from the CCHS and 5321 from the CHMS, weighted to represent 16 million people. Based on accelerometers, both pregnant and non-pregnant adults spent 9.5 hours per day (70% of their time) engaged in sedentary behaviour. Across all survey years, ages, and Canadian regions, pregnant adults, especially those aged under 35 years, spent less time engaged in moderate-to-vigorous physical activity (MVPA) compared with non-pregnant adults. Pregnant adults reported 34.3 minutes (95% CI 30.5-38.2) and objectively accrued 14.9 minutes (95% CI 7.9-21.8) in MVPA per day - 15.1 and 8.9 fewer minutes than non-pregnant adults, respectively. After accounting for self-report bias, only 27.5% (95% CI 24.1-31.0) of the pregnant and 41.1% (95% CI 40.4-41.9) of the non-pregnant adults met the Canadian physical activity guidelines (i.e., ≥150 minutes of MVPA per week).

CONCLUSION

Physical activity levels are remarkably low among both pregnant and non-pregnant adults, with few meeting current guidelines. Given the substantial physical and mental health benefits, more support is needed to increase pre-pregnancy and prenatal activity in Canada.

Activity Restriction and Hospitalization in Pregnancy: Can Bed-Rest Exercise Prevent Deconditioning? A Narrative Review

Evidence suggests that exercise during pregnancy is beneficial to both parent and fetus. However, there are high-risk pregnancy conditions that may warrant hospitalization. In our narrative review, we first describe the clinical implications for activity restriction in pregnancy, the effects of hospitalization, and the impact of bed rest on non-pregnant individuals. We provide examples of a 30 min bed-rest exercise program for hospitalized pregnant patients using the principal of suggested frequency, intensity, time (duration) of activity, and type of activity (FITT) using a resistance tool while in bed. If the individual is able to ambulate, we recommend short walks around the ward. Every minute counts and activity should be incorporated into a program at least 3 times per week, or every day if possible. As in all exercise programs, motivation and accountability are essential. Flexibility in timing of the exercise intervention is important due to the scheduling of medical assessments that may occur throughout the day for these hospitalized patients. Evidence suggests that by improving physical and emotional health through a bed-rest exercise program during a hospitalized pregnancy may help the individual resume demanding daily activity in the postpartum period and improve quality of life once birth has occurred. More research is necessary to improve the health of those individuals who are hospitalized during pregnancy, with follow up and support into the postpartum period.

Monitoring one heart to help two: heart rate variability and resting heart rate using wearable technology in active women across the perinatal period

BACKGROUND

Characterizing normal heart rate variability (HRV) and resting heart rate (RHR) in healthy women over the course of a pregnancy allows for further investigation into disease states, as pregnancy is the ideal time period for these explorations due to known decreases in cardiovascular health. To our knowledge, this is the first study to continuously monitor HRV and RHR using wearable technology in healthy pregnant women.

METHODS

A total of 18 healthy women participated in a prospective cohort study of HRV and RHR while wearing a WHOOP® strap prior to conception, throughout pregnancy, and into postpartum. The study lasted from March 2019 to July 2021; data were analyzed using linear mixed models with splines for non-linear trends.

RESULTS

Eighteen women were followed for an average of 405.8 days (SD = 153). Minutes of logged daily activity decreased from 28 minutes pre-pregnancy to 14 minutes by third trimester. A steady decrease in daily HRV and increase in daily RHR were generally seen during pregnancy (HRV Est. = - 0.10, P < 0.0001; RHR Est. = 0.05, P < 0.0001). The effect was moderated by activity minutes for both HRV and RHR. However, at 49 days prior to birth there was a reversal of these indices with a steady increase in daily HRV (Est. = 0.38, P < 0.0001) and decrease in daily RHR (Est. = - 0.23, P < 0.0001), regardless of activity level, that continued into the postpartum period.

CONCLUSIONS

In healthy women, there were significant changes to HRV and RHR throughout pregnancy, including a rapid improvement in cardiovascular health prior to birth that was not otherwise known. Physical activity minutes of any type moderated the known negative consequences of pregnancy on cardiovascular health. By establishing normal changes using daily data, future research can now evaluate disease states as well as physical activity interventions during pregnancy and their impact on cardiovascular fitness.

Abnormal placental villous maturity and dysregulated glucose metabolism: implications for stillbirth prevention

OBJECTIVES

In the UK one in 250 pregnancies end in stillbirth. Abnormal placental villous maturation, commonly associated with gestational diabetes, is a risk factor for stillbirth. Histopathology reports of placental distal villous immaturity (DVI) are reported disproportionately in placentas from otherwise unexplained stillbirths in women without formal diagnosis of diabetes but with either clinical characteristics or risk factors for diabetes. This study aims to establish maternal factors associated with DVI in relation to stillbirth.

METHODS

Placental histopathology reports were reviewed for all pregnant women delivering at University College London Hospital between July 2018 to March 2020. Maternal characteristics and birth outcomes of those with DVI were compared to those with other placental lesions or abnormal villous maturation.

RESULTS

Of the 752 placental histopathology reports reviewed, 11 (1.5%) were reported as diagnostic of DVI. Eighty cases were sampled for clinical record analysis. All women with DVI had normal PAPP-A (>0.4 MoM), normal uterine artery Doppler studies (UtA-PI) and were normotensive throughout pregnancy. Nearly one in five babies (2/11, 18.5%) with DVI were stillborn and 70% had at least one high glucose test result in pregnancy despite no formal diagnosis of diabetes.

CONCLUSIONS

These findings suggest that the mechanism underlying stillbirth in DVI likely relates to glucose dysmetabolism, not sufficient for diagnosis using current criteria for gestational diabetes, resulting in placental dysfunction that is not identifiable before the third trimester. Relying on conventional diabetes tests, foetal macrosomia or growth restriction, may not identify all pregnancies at risk of adverse outcomes from glucose dysmetabolism.

To Be Active or to Stop? A Cross-Sectional Retrospective Study Exploring Provider Advice and Patient Fears Surrounding Physical Activity in Pregnancies Complicated by Fetal Growth Restriction

Exercise guidance for women with pregnancies complicated by fetal growth restriction (FGR) is vague, despite the fact that physical activity during pregnancy improves placental development, placental blood flow, and encourages healthy fetal growth. The goal of this study is to test the hypothesis that women with pregnancies complicated by FGR are fearful of physical activity and are being given unclear or limited advice from healthcare providers. Participants (N = 78) (women who delivered an infant diagnosed with FGR within the past 5 years) took an electronic survey including demographic information, pregnancy information, provider advice recall, and other health-related information relevant to growth-restricted pregnancies. Quantitative and qualitative (post-positivism paradigm) methods were employed to analyze the data. When asked specifically about how the FGR diagnosis impacted their activity levels, nearly 50% of participants said the diagnosis led them to decrease their activity levels. Participants reported that healthcare providers who do discuss activity with pregnant patients with FGR suggest low-intensity activities or ceasing activity, although the majority of providers did not discuss activity at all. More fears surrounding physical activity were reported post-FGR diagnosis, including worrying about fetal growth and development and causing fetal harm when engaging in physical activity.