A PROSPECTIVE COHORT STUDY OF THE ASSOCIATION BETWEEN VIGOROUS EXERCISE DURING PREGNANCY AND PREGNANCY OUTCOME Sarah Lee Research Midwife Central Manchester University Hospitals NHS Foundation Trust Master of Clinical Research School of Nursing, Midwifery and Social Work The University of Manchester
Introduction NHS guidelines recommend that adults should undertake 150 minutes of moderate intensity aerobic activity every week (NHS, 2013) The Royal College of Obstetricians and Gynaecologists recommend that pregnant women should participate in four aerobic exercise sessions per week lasting at least 30 minutes each (RCOG, 2006) A Cochrane review from 2010 reported the impact of prolonged and repeated aerobic exercise on clinical outcomes for mother and infant are still unknown (Kramer and McDonald, 2010)
Literature Review The broad aim of the literature search was to examine the evidence for undertaking recreational exercise whilst pregnant The PICO framework was used to frame and answer the clinical question (Schardt et al., 2007) Patient = pregnant women Intervention = recreational exercise in pregnancy Comparison = no exercise in pregnancy Outcome = all relevant clinical outcomes of pregnancy “ Do pregnant women who carry out recreational exercise in pregnancy have different clinical outcomes than those who do not carry out recreational exercise?”
Literature Review An online search was undertaken in September 2011 and repeated in September 2013 Seventeen papers reporting primary research studies and two systematic reviews formed the basis of the literature review Four themes emerged concerning exercise in pregnancy and pregnancy outcome 1. Effect of exercise on mode of birth 2. Effect of exercise on birth weight 3. Effect of exercise on gestation at birth 4. Effect of exercise on length of labour
Exercise and mode of birth Findings were mixed with all studies having faults in their design One small study showed that exercise increases the chance of a spontaneous vaginal birth when compared with instrumental birth One study found women who exercise have a non-significant increased chance of a vaginal birth (unassisted or assisted) Two studies established that exercise does not affect mode of birth
Exercise and birth weight There is conflicting evidence regarding exercise in pregnancy and birth weight The latest Cochrane review (Kramer and McDonald, 2010) shows that exercise has no impact on birth weight Other studies demonstrate that women who exercise: – are less likely to have an LGA infant – are protected against LBW infants
Summary of findings Exercise may influence all of these outcomes Data are inconsistent and conflicting The main gaps in current knowledge are how exercise in pregnancy affects – mode of birth – birth weight.
Research Question The study aimed to investigate the relationship between vigorous exercise during the first 21 weeks of pregnancy and its effect on – mode of birth – birth weight – onset of labour – length of labour The hypothesis was that women undertaking vigorous exercise in the first 21 weeks of pregnancy had an increased chance of a spontaneous vaginal birth at term
Methods Data for this study were collected as part of the SCOPE study from 2004 to 2012 – A prospective, international multicentre cohort study of healthy nulliparous women with a singleton pregnancy – Participants completed a lifestyle questionnaire at two time points in their pregnancy to provide data on vigorous exercise Secondary analysis of data from SCOPE to examine the influence of exercise on pregnancy outcome 3376 women with uncomplicated pregnancies were extracted from the SCOPE dataset for this study A quantitative approach to analysis was used
The Lifestyle Questionnaire Vigorous exercise question in the SCOPE lifestyle questionnaire How often have you engaged in vigorous exercise in the last month? (exercise which made you breathe harder or puff or pant such as tennis, jogging, aerobics, heavy gardening, rollerblading, skiing, rowing, rowing/cycling machine) 1 - Never 2 - Once a week 3 - 2-3 time each week 4 - 4-6 times per week 5 - Daily 6 - More than once a day
Analysis Closed questions answered by participants in the lifestyle questionnaires were converted into numerical answers for statistical analysis using IBM SPSS 20 Main analysis involved the estimation of associations between vigorous exercise and clinical outcomes of pregnancy, adjusted for the presence of other potentially confounding factors A statistical significance level of p ≤ 0.05 was used for all tests performed
Prevalence of Exercise in Pregnancy • Pregnancy weeks 11-15 – 2175 (64.4%) never exercised – 1105 (32.7%) exercised 1-3 times per week – 96 (2.8%) exercised 4+ times per week • Pregnancy weeks 16-20 – 2012 (61.9%) never exercised – 812 (25.0%) exercised 1-3 times per week – 426 (13.1%) exercised 4+ times per week
Mode of Birth Engaged in vigorous Whole Statistical cohort Analysis exercise between 11-15 weeks ≥ 4 times Never 1-3 times per week per week Sample size (N) 2175 1105 96 (2.8%) 3376 (64.4%) (32.7%) 2 = 11.67 Mode of X 1567 Spontaneous 973 543 51 df = 6 (46.4%) birth vaginal birth (44.8%) (49.1%) (53.1%) p =0.070 Operative 641 275 27 943 vaginal (29.5%) (24.9%) (28.1%) (27.9%) Birth Pre-labour 152 83 5 240 Caesarean (7.0%) (7.5%) (5.2%) (7.1%) Caesarean in 408 204 13 625 Labour (18.8%) (18.5%) (13.5%) (18.5%)
Mode of Birth Whole Statistical Engaged in vigorous Cohort Analysis exercise between 16-20 weeks ≥ 4 times Never 1-3 times per week per week Sample Size (N) 2012 812 426 3250 (61.9%) (25.0%) (13.1%) 2 = 14.64 Mode of Spontaneous 891 418 201 1510 X (46.5%) df=6 birth vaginal birth (44.3%) (51.5%) (47.2%) p =0.023 Operative 594 202 112 908 Vaginal (29.5%) (24.9%) (26.3%) (27.9%) Pre-labour 137 59 29 225 Caesarean (6.8%) (7.3%) (6.8%) (6.9%) Caesarean in 389 133 84 606 labour (19.3%) (16.4%) (19.7%) (18.7%) A Significant Result!
Mode of Birth Mode of Birth Statistical Analysis Operative Prelabour LSCS in Whole SVD vaginal LSCS labour Cohort birth Sample size (N) 1567 943 240 625 3375 2 =9.22 Engaged in Never 973 641 152 408 2174 Pearson X (29.5%) (7.0%) (18.8%) (100%) df = 3 vigorous (44.8%) p =0.026 exercise at 15 weeks ≥ 1 per 302 88 217 1201 594 (25.1%) (7.3%) (18.1%) (100%) week (49.5%) 2 =11.57 Engaged in Never 891 594 137 389 2011 Pearson X (29.5%) (6.8%) (19.3%) (100%) df = 3 vigorous (44.3%) p =0.009 exercise at ≥ 1 per 314 88 217 1238 20 weeks 619 (25.4%) (7.1%) (17.5%) (100%) week (50.0%) very similar results and both statistically significant
Study findings: Mode of Birth Bivariable analyses demonstrated that women who performed vigorous exercise in weeks 11-15 or 16-20 of pregnancy were more likely to have a spontaneous vaginal birth compared with an operative vaginal birth or caesarean section in labour Multivariable analyses confirmed that any vigorous exercise in weeks 11-20 was associated with spontaneous vaginal birth
Birth weight Engaged in vigorous exercise Whole Statistical between 11-15 weeks cohort Analysis ≥ 4 times Never 1-3 times per week per week Sample Size (N) 2175 1105 96 3376 (64.4%) (32.7%) (2.8%) Birth weight Mean birth 3581g 3624g 3524g 3593.46 F = 5.670 (grams) weight (400.19) (392.75) (409.98) (398.60) df = 2 and 3373 (SD) p =0.003 95% 3564.35 3600.48 to 3441.01 3580.01 confidence to 3646.84 to to Interval 3598.01 3607.24 3606.91 Range 2546 to 2600 to 2645 to 2646 to 5110 4940 4990 5110 A Significant Result!
Birth weight Engaged in vigorous exercise Whole Statistical between 16-20 weeks Cohort Analysis ≥ 4 times Never 1-3 times per week per week Sample Size (N) 2012 812 426 3250 (61.9%) (25.0%) (13.1%) Birth weight Mean birth 3586g 3607g 3580g 3590.56 F = 0.985, (grams) weight (401.39) (405.02) (361.26) (397.29) df = 2 and (SD) 1083.302 p =0.374 95% 3568.46 3579.31 to 3545.90 to 3576.89 confidence to 3635.11 3614.70 to interval 3603.56 3601.22 Range 2546 to 2600 to 2605 to 2546 to 5060 5110 4635 5110
Birth weight 95% confidence interval for Difference in p -value birth weight birth weight Lower bound Upper bound 5.036 60.852 Vigorous 33g p=0.021 exercise at 15 weeks Vigorous 13g p=0.352 -14.639 41.108 exercise at 20 weeks BMI at 15 weeks 17g <0.001 13.72 19.906 Age of participant -1.7g 0.252 -4.783 1.253 Smoking status at -118g <0.001 -165.649 -69.589 15 weeks
Study findings: Birth weight Bivariable analyses demonstrated that in pregnancy weeks 11-15 exercise was associated with a slight increase in birth weight – Women who vigorously exercised 1-3 times per week during weeks 11-15 were more likely to give birth to heavier infants than those who did not exercise at all – Women who vigorously exercised four or more times per week had the lightest infants – Difference in mean birth weight was only 100g Multivariable analyses confirmed any vigorous exercise in weeks 11-15 was associated with an increase in birth weight
Recommend
More recommend
