THE EFFECT OF PERINATAL PHYSICAL ACTIVITY ON METABOLIC HEALTH AND VASCULAR FUNCTION DURING PREGNANCY

Mohd Salleh, N (2025) THE EFFECT OF PERINATAL PHYSICAL ACTIVITY ON METABOLIC HEALTH AND VASCULAR FUNCTION DURING PREGNANCY. Doctoral thesis, Liverpool John Moores University.

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Abstract

Gestational diabetes mellitus (GDM) is associated with adverse maternal and foetal outcomes, and physical activity (PA) has been shown to play a crucial role in improving glucose regulation and overall maternal health in healthy pregnancy. However, the influence of PA on glucose variability in GDM pregnancies remains unclear. Despite the well-documented benefits of PA, many pregnant females reduce their activity levels, particularly in the later stages of their pregnancy. A GDM diagnosis may further discourage PA due to medical concerns and a lack of clear guidance. To date, qualitative insights into the perception of PA in females diagnosed with GDM remain lacking.
Additionally, limited evidence exists on the influence of PA on glucose variability and the effects of sedentary behaviour during pregnancy in both GDM and healthy pregnancy. Sedentary behaviour, which is defined as waking activities in sitting, reclining, or lying posture with low energy expenditure (≤1.5 METs), has also emerged as a potential risk factor for adverse pregnancy outcomes. While some evidence suggests that prolonged sedentary time may impair glycaemic control and cardiometabolic health, little is known about whether breaking up this behaviour can offer protective benefits during pregnancy.
This thesis investigates the role of PA in glucose variability across the perinatal period in females with GDM, identifies barriers and facilitators to PA in GDM pregnancies, and examines the acute cardiovascular and metabolic effects of prolonged and breaking up the sedentary time in healthy pregnancies.
A multi-methods approach was employed across three studies. Study 1 (Chapter 3) presents a longitudinal observational study assessing PA levels and glucose variability during pregnancy and postpartum in 30 females diagnosed with GDM using an accelerometer and continuous glucose monitoring (CGM). Multiple regression analysis and partial correlation were performed to examine associations. Findings showed 24-hour glucose variability increased significantly across the perinatal period [F(2, 43)=3.419, P=0.042, η²=0.137] and remained 15.38% higher in postpartum than in trimester 2 (T2). PA levels were lower at trimester 3 (T3) compared to T2, with a mean difference of 9 mg in average acceleration, equivalent to a small but meaningful reduction in physiological implications for maternal and foetal health. PA was not a significant predictor of glucose variability (GV) at any time point (P>0.05). Despite reduced PA, participants were still active enough to meet PA guidelines and 96% kept their GV below 30%, suggesting that dietary and medical management, played a dominant role in glycaemic control.
Study 2 (Chapter 4) explored the experiences, barriers, and facilitators of PA engagement among females diagnosed with GDM using semi-structured interviews (n=15) and analysed using reflexive thematic analysis. Three over-arching themes, each with their own sub-themes, were co-created from these data: Managing GDM, Facilitators to Engaging in PA, and Barriers to Engaging in PA. Interestingly, this study demonstrates that GDM diagnosis both hinders and facilitates antenatal PA and stresses the need for healthcare professionals' guidance surrounding PA. Importantly, this study highlights the need for better education for healthcare providers and specific antenatal PA guidelines for GDM pregnancies.
Study 3 (Chapter 5) presents a randomised crossover trial in which twenty healthy pregnant females completed two conditions: uninterrupted sitting (3hours) and breaking up sitting time by 3 min walking breaks every 30 min. Vascular function was assessed using flow-mediated dilation (FMD) of the femoral and brachial arteries. PA and GV were assessed during the laboratory phase, 24- and 48-hours post sitting intervention. A two-way repeated ANOVA examined the acute main effects of protocol (laboratory phase), while a linear mixed model assessed glucose response over time. Breaking up prolonged sitting significantly improved femoral artery vascular function, including increases in peak response and FMD percentage (P<0.05). In contrast, brachial artery responses were more variable, with no significant changes in FMD observed but did not significantly affect glucose variability. Prolonged sitting was associated with lower glucose variability and fewer low-glucose episodes. No significant differences in glucose variability were observed in free-living conditions over 24 and 48 hours. These findings suggest that regular movement breaks can mitigate the vascular consequences of prolonged SB during pregnancy, though their impact on glucose regulation remains unclear.
This thesis contributes new insights into the complex interplay between PA, glucose variability, and sedentary behaviour in pregnancy. The findings support integrating PA promotion and sedentary behaviour reduction strategies into antenatal care to enhance both metabolic and cardiovascular function outcomes for mother.

Item Type:	Thesis (Doctoral)
Uncontrolled Keywords:	pregnancy; physical activity; sedentary behaviour; gestational diabetes; cardiometabolic health
Subjects:	R Medicine > RC Internal medicine > RC1200 Sports Medicine
Divisions:	Sport and Exercise Sciences
Date of acceptance:	4 June 2025
Date Deposited:	27 Jun 2025 16:03
Last Modified:	27 Jun 2025 16:04
DOI or ID number:	10.24377/LJMU.t.00026655
Supervisors:	Sprung, V, Boddy, L, Hesketh, K and Sheen, K
URI:	https://researchonline.ljmu.ac.uk/id/eprint/26655

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