Maternal daily activity in low risk pregnancy : a longitudinal study
A review of the scientific literature revealed a lack of information regarding the integrated daily activity levels of low-risk pregnant women in contemporary Western society. A prospective, longitudinal study was therefore undertaken to (i) assess the impact of low-risk pregnancy on the daily activity levels of healthy, British primigravid women and (ii) examine the relationship between total maternal daily activity level and pregnancy outcome. The best combination of methods to measure daily activity levels during pregnancy was considered to be a subjective self-report measure used in conjunction with an objective ambulatory activity monitor. These methods were developed and were demonstrated to be both reliable and valid in non-pregnant women. However, the study identified some unique problems in using activity monitors in pregnant women. These problems emanated both from women's reluctance to wear an activity monitor when pregnant and from a need to measure extremely low levels of activity in late gestation. Both data from the ambulatory monitor and the new activity questionnaire demonstrated a overall decrease in mean maternal daily activity levels between 25 & 38 weeks gestation (n=51; p<0.01). This decline masked different maternal responses in different activity domains. The mean occupational activity ratios of women working full-time declined steadily between 16 & 34 weeks gestation (n=25, p<0.01). Women's working hours and the more flexible elements of their work were reduced whilst the frequency of work breaks increased. Between 25 & 38 weeks gestation, mean recreational activity ratios also declined (n=50, p<0.05). Participation in structured sports and exercise ceased and increasing amounts of time were spent within the home. In contrast, mean overall domestic activity ratios were maintained. Between 16 & 38 weeks gestation mean nocturnal activity ratios increased steadily (n=47; p=0.01) To maintain waking activity during pregnancy, women actively engaged in a number of different balancing strategies. These strategies comprised monitoring, prioritising, pacing and forward planning. Despite the changes that occurred in maternal activity behaviour, one of the strongest and most consistent predictors of maternal activity behaviour during pregnancy was that of maternal activity behaviour prior to pregnancy. Occupational activity levels pre-pregnancy were independently associated with maternal daily activity levels at 12,16 & 25 weeks gestation (p=0.004-0.020). Self-efficacy was the only significant predictor of the change in maternal daily activity levels between 25 & 38 weeks gestation (p=0.013). The women who reduced their activity the most were likely to be those individuals who had more difficulty in overcoming perceived barriers to physical activity participation. Five main barriers to physical activity were identified: (i) the physical symptoms of pregnancy (ii) the effect of outside influences (iii) a lack of motivation (iv) a low maternal body image and (v) a lack of time and/or appropriate facilities. Findings suggested that maternal daily activity may impact significantly on pregnancy outcome. Higher maternal daily activity at 16 weeks gestation was independently associated with a lower incidence of emergency caesarean section (p<0.05). Higher maternal daily activity at 38 weeks gestation was independently associated with a higher incidence of an induction of labour (p<0.05). Total daily activity at 25 & 34 weeks gestation was independently and negatively associated with infant birthweight (p<0.05).