Validation of self-reported recreational exercise in pregnant women in the Norwegian Mother and Child Cohort Study

Mercury exposure in the Norwegian Mother, Father, and Child Cohort Study - measured and predicted blood concentrations and associations with birth weight

Background

Blood total mercury concentration (BTHg) predominantly contains methyl Hg from seafood, and less inorganic Hg. Measured BTHg is often available only in a small proportion of large cohort study samples. Associations between estimated dietary intake of total Hg (THg) and lower birth weight within strata of maternal seafood intake was previously reported in the Norwegian Mother, Father, and Child Cohort Study (MoBa). However, maternal seafood consumption was associated with increased birth weight, indicating negative confounding by seafood in the association between THg intake and birth weight. Using predicted BTHg as a proxy for measured BTHg, we hypothesized that predicted BTHg would be associated with decreased birth weight.

Objectives

To develop and validate a prediction model for BTHg in MoBa and to examine the association between predicted BTHg and birth weight in the MoBa population.

Methods

Using linear regression, measured maternal BTHg (n = 1437) was used to build the best fitting model (highest R-squared value). Model validation (n = 1436) was based on correlation and weighted Kappa (Кw). Associations between predicted BTHg in the MoBa population (n = 86,775) or measured BTHg (n = 3590) and birth weight were assessed by multivariate linear regression models.

Results

The best fitting model had R-squared = 0.3 and showed strong correlation (r = 0.53, p < 0.001) between predicted and measured BTHg. Cross-classification (quintiles) showed 73 % correctly classified and 3.3 % grossly misclassified, with Кw of 0.37. Measured BTHg was not associated with birth weight. Predicted BTHg was significantly associated with higher birth weight. There were no trends in birth weight with increasing quintiles of measured or predicted BTHg after stratification into high or low seafood consumption.

Conclusions

The results indicate that prediction of BTHg did not overcome negative confounding of the association between Hg exposure and birth weight by seafood intake. Furthermore, effect on birth weight of toxicological concern is unexpected in our observed BTHg range.

The Impact of Exercising on Pelvic Symptom Severity, Pelvic Floor Muscle Strength, and Diastasis Recti Abdominis After Pregnancy: A Longitudinal Prospective Cohort Study

OBJECTIVE

The objective of this study was to evaluate whether early postpartum exercise is associated with changes in pelvic symptom severity, pelvic floor muscle strength, and diastasis recti abdominis (DRA) from 3 to 12 months postpartum.

METHODS

In this prospective cohort study, 504 participants with and without pelvic symptoms (pelvic girdle pain, stress urinary incontinence, vaginal heaviness) were followed. At 3, 6, 9, and 12 months postpartum, we assessed pelvic symptoms, exercise behavior (by questionnaires), pelvic floor muscle strength (by vaginal palpation), and DRA (by caliper measurement). Based on the 3-months questionnaire, participants were categorized as nonexercisers (n = 105), minimal low-impact exercisers (n = 249), regular low-impact exercisers (n = 117), and high-impact exercisers (n = 32). Between-group differences and within-group changes from 3 to 12 months were calculated using Chi-square tests, Kruskal-Wallis tests, and Friedman analysis of variance.

RESULTS

At 3 months, no differences in symptom prevalence were seen between the groups. Nonexercisers reported higher pelvic girdle pain severity and had weaker pelvic floor muscles. The within-group analysis showed that pelvic girdle pain severity did not change in nonexercisers or high-impact exercisers, but decreased in minimal and regular low-impact exercisers. Stress urinary incontinence increased in nonexercisers from 3 to 12 months, while it remained unchanged in regular low-impact and high-impact exercisers, and decreased in minimal low-impact exercisers. Across all groups, vaginal heaviness and DRA decreased, and pelvic floor strength increased from 3 to 12 months.

CONCLUSION

The study indicates that early low-impact exercising is associated with reduced pelvic girdle pain severity during the first postpartum year. Minimal low-impact exercisers also showed a slight reduction in stress urinary incontinence. Conversely, nonexercisers reported an increase in stress urinary incontinence between 3 and 12 months postpartum.

IMPACT

Physical therapists should encourage women to start with low-impact exercise early after pregnancy.

LAY SUMMARY

This study highlights the positive effects of starting gentle, low-impact exercise early after childbirth to reduce pelvic girdle pain and urinary incontinence.

Maternal physical activity and sitting time and its association with placental morphology and blood flow during gestation: Findings from the Queensland Family Cohort study

OBJECTIVES

Antenatal exercise is associated with placental morphological alterations, however research in this area is limited. Given the emphasis on the beneficial effects of antenatal exercise, it is important to understand its effect on placental function and the relationship to foetal development. The aim of this study was to investigate the association between physical activity, sitting time, and placental outcomes measured during gestation.

DESIGN

Prospective cohort study.

METHODS

Pregnant women in the Queensland Family Cohort study self-reported physical activity at 24 and 36 weeks of gestation (n = 203) and were categorised into physical activity volume groups of nil-low (0-<500 metabolic equivalent of task·minutes/week), moderate (500-<1000 metabolic equivalent of task·minutes/week), or high-volume activity (≥1000 metabolic equivalent of task·minutes/week). Participants reported average daily sitting time, whereby excessive sitting time was considered as ≥8h/day. Placental stiffness, thickness, and uteroplacental blood flow resistance were measured by ultrasound imaging at each timepoint.

RESULTS

Physical activity volume was not associated with changes to placental morphometrics or uteroplacental blood flow resistance at 24 or 36 weeks of gestation. Excessive sitting time at 36 weeks was associated with greater placental stiffness (p = 0.046), and a lower umbilical artery pulsatility index (p = 0.001).

CONCLUSIONS

Placental tissue stiffness and umbilical artery resistance were altered in late gestation with higher maternal sitting time but not with physical activity volume. Overall, excessive sitting time may be a risk for suboptimal placental function and could be an important focus for antenatal care.

Update and Novel Validation of a Pregnancy Physical Activity Questionnaire

The aim of this study was to update and validate the Pregnancy Physical Activity Questionnaire (PPAQ), using novel and innovative accelerometer and wearable camera measures in a free-living setting, to improve the measurement performance of this method for self-reporting physical activity. A prospective cohort of 50 eligible pregnant women were enrolled in early pregnancy (mean = 14.9 weeks' gestation). In early, middle, and late pregnancy, participants completed the updated PPAQ and, for 7 days, wore an accelerometer (GT3X-BT; ActiGraph, Pensacola, Florida) on the nondominant wrist and a wearable camera (Autographer; OMG Life (defunct)). At the end of the 7-day period, participants repeated the PPAQ. Spearman correlations between the PPAQ and accelerometer data ranged from 0.37 to 0.44 for total activity, 0.17 to 0.53 for moderate- to vigorous-intensity activity, 0.19 to 0.42 for light-intensity activity, and 0.23 to 0.45 for sedentary behavior. Spearman correlations between the PPAQ and wearable camera data ranged from 0.52 to 0.70 for sports/exercise and from 0.26 to 0.30 for transportation activity. Reproducibility scores ranged from 0.70 to 0.92 for moderate- to vigorous-intensity activity and from 0.79 to 0.91 for sports/exercise, and were comparable across other domains of physical activity. The PPAQ is a reliable instrument and a valid measure of a broad range of physical activities during pregnancy.

Intake of sucrose-sweetened beverages and risk of developing pharmacologically treated hypertension in women: cohort study

Objective

To investigate the association between intake of sucrose-sweetened beverages (SSBs) and risk of developing pharmacologically treated hypertension in a population of Norwegian mothers followed up to 10 years after delivery.

Design

Women without hypertension at baseline in the Norwegian Mother, Father and Child Cohort Study (n=60 027) who delivered between 2004 and 2009 were linked to the Norwegian Prescription Database to ascertain antihypertensive medication use after the first 90 days following delivery. Diet was assessed by a validated semiquantitative Food Frequency Questionnaire in mid pregnancy. Cox proportional hazard analyses evaluated HRs for the development of hypertension associated with SSB consumption as percent energy by quintiles in multivariable models. Supplemental analyses were stratified by gestational hypertension and by a low versus high sodium-to-potassium intake ratio (<0.78 compared with ≥0.78).

Results

A total of 1480 women developed hypertension within 10 years of follow-up. The highest relative to the lowest quintile of SSB intake was associated with an elevated risk for hypertension after adjusting for numerous covariates in adjusted models (HR: 1.20 (95% CI: 1.02 to 1.42)). Consistency in results was observed in sensitivity analyses. In stratified analyses, the high SSB intake quintile associated with elevated hypertension risk among women who were normotensive during pregnancy (HR: 1.25 (95% CI: 1.03 to 1.52)), who had normal body mass index (HR: 1.49 (95% CI: 1.13 to 1.93)) and among women with low sodium to potassium ratio (HR: 1.33 (95% CI: 1.04 to 1.70)).

Conclusions

This study provides strong evidence that SSB intake is associated with an increased risk of hypertension in women.

No association between maternal exercise during pregnancy and the child's weight status at age 7 years: The MoBa study

INTRODUCTION

Maternal lifestyle during pregnancy may affect the development of overweight and obesity in the child. We examined whether maternal exercise during pregnancy is associated with offspring overweight and obesity in childhood. A secondary aim was to examine whether the association is affected by the child's physical activity level.

MATERIALS AND METHODS

This study is based on data from the Norwegian Mother, Father and Child Cohort Study (MoBa), including 44 352 pregnancies and children (n = 32 304 in week 17 and n = 32 419 in week 30 in the final adjusted model). Maternal exercise during pregnancy was self-reported in gestational weeks 17 and 30. We conducted linear and logistic regression separately for girls and boys, and outcomes were the child's body mass index (BMI) and weight status (overweight/obese) at age 7 years. We further examined the additive joint association between maternal exercise during pregnancy and the child's leisure time physical activity on weight status at age 7 years.

RESULTS

In total, 12.4% of the children were classified as overweight or obese, and 1.7% as obese. The results suggest no association between maternal exercise in both gestational weeks 17 and 30 and the weight status of the child at age 7 years. The association between maternal exercise and the child's weight status at age 7 years appears not to be affected by the child's physical activity level.

CONCLUSION

Maternal exercise level during pregnancy does not appear to be associated with the child's BMI or odds of being overweight or obese in childhood.

Physical activity in pregnancy: a Norwegian-Swedish mother-child birth cohort study

BACKGROUND

Physical activity during pregnancy is important for maternal and offspring health. Optimal conditions during pregnancy may help reduce the burden of noncommunicable diseases. National and international guidelines recommend at least 150 minutes of physical activity of at least moderate intensity per week. To optimize physical activity in pregnant women, it is important to identify factors associated with higher levels of physical activity.

OBJECTIVE

This study aimed to explore types and levels of physical activity in midpregnancy in Norway and Sweden and to identify factors associated with higher levels of physical activity.

MATERIALS AND METHODS

From the population-based mother-child cohort Preventing Atopic Dermatitis and Allergies in Children study recruiting 2697 women in Norway and Sweden from 2014 to 2016, we included 2349 women who answered an electronic questionnaire at enrollment in midpregnancy. Women were asked about regular physical activity in the last 2 weeks of pregnancy and afterward for types and levels of physical activity in pregnancy and before pregnancy and socioeconomic status, lifestyle, and maternal health. Logistic regression analyses were used to identify factors associated with higher levels of physical activity in pregnancy, defined as >30 minutes per session of ≥2 times per week of moderate- or high-intensity brisk walking, strength training, jogging, and bicycling.

RESULTS

No regular physical activity during the last 2 weeks before answering the questionnaire at midpregnancy was reported by 689 women (29%). In this study, 1787 women (76%) reported weekly strolling during pregnancy. Regular physical activity at least twice weekly in the first half of pregnancy was reported as brisk walking by 839 women (36%), bicycling by 361 women (15%), strength training by 322 women (14%), and other activities by <10% of women. Among the 1430 women with regular moderate- or high-intensity physical activity, the estimated median duration per week was 120 minutes. Higher physical activity levels were achieved in 553 women (23.5%) by brisk walking, 287 women (12.2%) by strength training, 263 women (11.2%) by bicycling, and 114 women (4.9%) by jogging. Higher physical activity levels were positively associated with regular physical activity before pregnancy, dog ownership, and atopic dermatitis and negatively associated with higher body mass index, study location in Østfold, previous pregnancy or pregnancies, non-Nordic origin, suburban living, and sick leave.

CONCLUSION

At midpregnancy, 29% of women were inactive, and less than 50% of women had at least 2 hours of moderate-intensity physical activity weekly. Awareness of physical activity in pregnancy should be discussed at pregnancy follow-up visits, particularly among women with higher body mass index, sick leave, previous pregnancy or pregnancies, and non-Nordic origin.

Leisure-time physical activity before pregnancy and risk of hyperemesis gravidarum: a population-based cohort study

INTRODUCTION

Women who experience severe nausea and vomiting in early pregnancy are less likely to participate in leisure-time physical activity (LTPA) during pregnancy. Whether LTPA before pregnancy is associated with hyperemesis gravidarum (HG) has not yet been studied. The aim of the study was to estimate associations between prepregnancy LTPA and HG in pregnancy.

METHODS

We present data from 37,442 primiparous women with singleton pregnancies enrolled in The Norwegian Mother and Child Cohort Study. Prepregnancy LTPA was self-reported by questionnaire in pregnancy week 17. HG was reported in week 30 and defined as prolonged nausea and vomiting in pregnancy requiring hospitalisation before the 25th gestational week. We estimated the crude and adjusted associations between LTPA and HG using multiple logistic regression. We assessed effect modification by prepregnancy BMI or smoking by stratified analysis and interaction terms.

RESULTS

A total of 398 (1.1%) women developed HG. Before pregnancy 56.7% conducted LTPA at least 3 times weekly, while 18.4% of women conducted LTPA less than once a week. Compared to women reporting LTPA 3 to 5 times weekly, women reporting no LTPA before pregnancy had an increased odds of HG (adjusted odds ratio (aOR) 1.69; 95% confidence interval (CI), 1.20 to 2.37). LTPA-HG associations differed by prepregnancy BMI but not by prepregnancy smoking.

DISCUSSION

Lack of LTPA before pregnancy was associated with an increased odds of HG. Due to few cases of HG and thereby low statistical power, one need to be cautious when interpreting the results of this study.

Physical Activity Questionnaires for Pregnancy: A Systematic Review of Measurement Properties

Background

In order to assess physical activity (PA) during pregnancy, it is important to choose the instrument with the best measurement properties.

Objectives

To systematically summarize, appraise, and compare the measurement properties of all self-administered questionnaires assessing PA in pregnancy.

Methods

We searched PubMed, Embase, and SPORTDiscus with the following inclusion criteria: (i) the study reported at least one measurement property (reliability, criterion validity, construct validity, responsiveness) of a self-administered questionnaire; (ii) the questionnaire intended to measure PA; (iii) the questionnaire was evaluated in healthy pregnant women; and (iv) the study was published in English. We evaluated results, quality of individual studies, and quality of evidence using a standardized checklist (Quality Assessment of Physical Activity Questionnaires [QAPAQ]) and the GRADE (Grading of Recommendation, Assessment, Development, and Evaluation) approach.

Results

Seventeen articles, reporting 18 studies of 11 different PA questionnaires (17 versions), were included. Most questionnaire versions showed insufficient measurement properties. Only the French and Turkish versions of the Pregnancy Physical Activity Questionnaire (PPAQ) showed both sufficient reliability and construct validity. However, all versions of the PPAQ pooled together showed insufficient construct validity. The quality of individual studies was usually high for reliability but varied considerably for construct validity. Overall, the quality of evidence was very low to moderate.

Conclusions

We recommend the PPAQ to assess PA in pregnancy, although the pooled results revealed insufficient construct validity. The lack of appropriate standards in data collection and processing criteria for objective devices in measuring PA during pregnancy attenuates the quality of evidence. Therefore, research on the validity of comparison instruments in pregnancy followed by consensus on validation reference criteria and standards of PA measurement is needed.

Electronic supplementary material

The online version of this article (10.1007/s40279-018-0961-x) contains supplementary material, which is available to authorized users.

Contrasting patterns of overweight and thinness among preschool children of different ethnic groups in Norway, and relations with maternal and early life factors

Background

Childhood obesity is a worldwide health challenge and risk factor for adult life obesity, which predisposes to development of type 2 diabetes and cardiovascular diseases. However, also thinness in early life has been related to these diseases, especially if followed by fat gain. In European countries, susceptibility to cardio-metabolic diseases varies considerably between ethnic groups. We investigated ethnic differences in overweight and thinness in a multi-ethnic, population-based cohort of preschool children in Norway, and associations with maternal and early postnatal factors.

Methods

Participants were children aged 4–5 years (n = 570) drawn from the population-based STORK Groruddalen cohort of healthy women and offspring followed from early pregnancy. Ethnic groups were: European (n = 298), South Asian (n = 154), and Middle East/North African (n = 118). Children’s growth data were provided from routine visits at local Child Health Clinics. Weight status was defined by the International Obesity Task Force. Using multinomial logistic regression analysis, we explored ethnic differences in overweight and thinness, and associations with maternal-, pre, − and postnatal factors.

Results

Children of Middle East/North African origin had higher prevalence of overweight (22.0%) compared to European (12.8%) children, and in adjusted logistic regression analysis almost the double risk (OR 1.98; 95%CI: 1.08–3.63). Prevalence was lower in children of South Asian origin (5.2%). Children with South Asian background had higher prevalence of thinness (26.0%) compared to ethnic Europeans (10.4%), and the double risk (OR 2.20; 95%CI: 1.25–3.87) in adjusted models. Applying newly suggested BMI adjustments in South Asian children, taking into account their relatively increased adiposity, markedly increased the prevalence of overweight, and decreased the prevalence of thinness in this subgroup. Birthweight and maternal prepregnant overweight were strongly, positively associated with overweight, and inversely associated with thinness. Lower maternal age was associated with overweight only.

Conclusions

In a multi-ethnic cohort we found strikingly different patterns of overweight and thinness among children of different ethnic groups at age 4–5 years, and a strong association between maternal BMI and their children’s weight status. More knowledge is needed on what characterizes and what promotes healthy growth patterns in multi-ethnic populations.

Electronic supplementary material

The online version of this article (10.1186/s12889-018-5952-1) contains supplementary material, which is available to authorized users.

Leisure Time Physical Activity and Gestational Diabetes Mellitus in the Omega Study

PURPOSE

Findings of studies investigating associations of leisure time physical activity (LTPA) with gestational diabetes mellitus (GDM) risk have been inconsistent. We investigated associations of LTPA with GDM and whether these associations differ by prepregnancy overweight/obese status or gestational weight gain category.

METHODS

Participants (N = 3209) of the Omega study, a pregnancy cohort study in Washington State (1996-2008), reported LTPA duration (h·wk) and energy expenditure (MET·h·wk) in the year before pregnancy and in early pregnancy. Diagnoses of GDM were abstracted from medical records. Poisson regression models were used to determine relative risks of GDM across tertiles of prepregnancy or early pregnancy LTPA duration and energy expenditure. Stratified analyses and interaction terms were used to assess effect modification by prepregnancy overweight/obese status (BMI ≥25 kg·m) or gestational weight gain category (adequate or excessive).

RESULTS

Each tertile increase in prepregnancy LTPA duration or energy expenditure was associated with 15% (95% CI = 0.72-1.00) and 19% (95% CI = 0.69-0.96) lower risk of GDM, respectively. Each tertile increase in early pregnancy LTPA duration or energy expenditure was associated with 16% (95% CI = 0.72-0.97) and 17% (95% CI = 0.72-0.95) lower risk of GDM, respectively. LTPA during both prepregnancy and early pregnancy was associated with a 46% reduced risk of GDM (95% CI = 0.32-0.89) compared with inactivity during both periods. LTPA-GDM associations were similar by prepregnancy BMI and gestational weight gain.

CONCLUSION

Our results support a role for the promotion of physical activity before and during pregnancy in the prevention of GDM.

Low Calcium Intake in Midpregnancy Is Associated with Hypertension Development within 10 Years after Pregnancy: The Norwegian Mother and Child Cohort Study

Background: Low dietary calcium intake may be a risk factor for hypertension, but studies conflict.Objective: We evaluated the ability to predict hypertension within 10 y after delivery based on calcium intake during midpregnancy.Methods: The Norwegian Mother and Child Cohort Study of women delivering in 2004-2009 was linked to the Norwegian Prescription Database (2004-2013) to ascertain antihypertensive medication usage >90 d after delivery. Women with hypertension before pregnancy were excluded, leaving 60,027 mothers for analyses. Age and energy-adjusted cubic splines evaluated dose-response curves, and Cox proportional hazard analyses evaluated HR and 95% CIs by calcium quartiles adjusting for 7 covariates. Analyses were stratified by gestational hypertension and by sodium-to-potassium intake ratio (<0.76 compared with ≥0.76).Results: Participants had a mean ± SD age of 30.5 ± 4.6 y, a body mass index (in kg/m²) of 24.0 ± 4.3 before pregnancy, and a mean follow-up duration of 7.1 ± 1.6 y. Cubic spline graphs identified a threshold effect of low calcium intake only within the range of dietary inadequacy related to increased risk. The lowest calcium quartile (≤738 mg/d; median: 588 mg/d), relative to the highest quartile (≥1254 mg/d), had an HR for hypertension of 1.34 (95% CI: 1.05, 1.70) among women who were normotensive during pregnancy, and an HR of 1.62 (95% CI: 1.14, 2.35) among women who had gestational hypertension, after adjusting for covariates. Women with gestational hypertension, who were in the lowest quartile of calcium intake, and who had a high sodium-to-potassium intake ratio had a risk of hypertension more than double that of their counterparts with a calcium intake in the highest quartile. Results were attenuated by adjusting for covariates (HR: 1.92; 95% CI: 1.09, 3.39).Conclusions: The results suggest that low dietary calcium intake may be a risk factor or risk marker for the development of hypertension, particularly for women with a history of gestational hypertension.

Reliability and concurrent validity of the International Physical Activity Questionnaire short form among pregnant women

ABSTRACT

Sanda B, Vistad I, Haakstad LAH, Berntsen S, Sagedal LR, Lohne-Seiler H, Torstveit MK. Reliability and concurrent validity of the International Physical Activity Questionnaire short form among pregnant women.

BACKGROUND

The International Physical Activity Questionnaire short-form (IPAQ-SF) is frequently used to assess physical activity (PA) level in the general adult population including pregnant women. However, the reliability and validity of the questionnaire in pregnancy is unknown. Therefore, the aims of the present study were to investigate test-retest reliability and concurrent validity of IPAQ-SF among pregnant women, and whether PA is reported differently among those who fulfill (active) vs. do not fulfill (inactive) recommendations of ≥150 min of weekly moderate intensity PA in pregnancy.

METHOD

Test-retest reliability was examined by answering IPAQ-SF twice, two weeks apart (n = 88). To assess validity, IPAQ-SF was compared to the physical activity monitor SenseWear Armband® (SWA) (n = 64). The participants wore SWA for 8 consecutive days before answering IPAQ-SF. PA level was reported as time spent in moderate-, vigorous- and moderate-to-vigorous intensity PA (MPA, VPA and MVPA) corresponding to the cut-off points 3-6, >6 and >3 Metabolic Equivalents (METs), respectively.

RESULTS

Test-retest intraclass-correlation of MPA, VPA and MVPA ranged from 0.81-0.84 (95% Confidence Intervals: 0.69,0.90). Comparing time spent performing PA at various intensities; the mean differences and limits of agreement (±1.96 Standard Deviation) from Bland-Altman plots were-84 ± 402 min/week for MPA,-85 ± 452 min/week for MVPA and 26 ± 78 min/week for VPA, illustrating that the total group under-reported MPA by 72% and MVPA by 52%, while VPA was over-reported by 1400%. For the inactive group corresponding numbers were 44 ± 327 min/week for MPA, 52 ± 355 min/week for MVPA and 16 ± 33 min/week for VPA, illustrating that the inactive group over-reported MPA by 13% and MVPA by 49%, while VPA was not detected by SWA, but participants reported 16 min of VPA/week. In contrast, corresponding numbers for the active group were-197 ± 326 min/week for MPA,-205 ± 396 min/week for MVPA and 35 ± 85 min/week for VPA, illustrating that the active group under-reported MPA by 81% and MVPA by 60%, while they over-reported VPA by 975%.

CONCLUSION

IPAQ-SF had good test-retest reliability, but low to fair concurrent validity for MPA, VPA and MVPA compared to an objective criterion measure among pregnant women. Further, women fulfilling PA guidelines in pregnancy under-reported, while inactive women over-reported PA level.

Exercise in pregnancy: an association with placental weight?

BACKGROUND

Women with high levels of physical exercise have an increased demand for oxygen and nutrients. Thus, in pregnancies of women with high levels of exercise, it is conceivable that the supply of oxygen and nutrients to the placenta is suboptimal, and growth could be impaired.

OBJECTIVE

The objective was to study the association of frequency of exercise during pregnancy with placental weight and placental to birthweight ratio.

STUDY DESIGN

This was a prospective study of 80,515 singleton pregnancies in the Norwegian Mother and Child Cohort Study. Frequency of exercise was self-reported by a questionnaire at pregnancy weeks 17 and 30. Information on placental weight and birthweight was obtained by linkage to the Medical Birth Registry of Norway.

RESULTS

Placental weight decreased with increasing frequency of exercise (tests for trend, P < .001). For nonexercisers in pregnancy week 17, the crude mean placental weight was 686.1 g compared with 667.3 g in women exercising ≥6 times weekly (difference, 18.8 g; 95% confidence interval, 12.0-25.5). Likewise, in nonexercisers in pregnancy week 30, crude mean placental weight was 684.9 g compared with 661.6 g in women exercising ≥6 times weekly (difference, 23.3 g; 95% confidence interval, 14.9-31.6). The largest difference in crude mean placental weight was seen between nonexercisers at both time points and women exercising ≥6 times weekly at both time points (difference, 31.7 g; 95% confidence interval, 19.2-44.2). Frequency of exercise was not associated with placental to birthweight ratio.

CONCLUSION

We found decreasing placental weight with increasing frequency of exercise in pregnancy. The difference in placental weight between nonexercisers and women with exercising ≥6 times weekly was small and may have no clinical implications.

Is consumption of sugar-sweetened soft drinks during pregnancy associated with birth weight?

In Norway, there were parallel increases and subsequent decreases in birth weight (BW) and consumption of sugar‐sweetened carbonated soft drinks (SSC) during the period 1990–2010, and by an ecological approach, we have suggested that the relationship was causal. The objective of this study was to examine if such a relationship was present in a prospectively followed cohort of pregnant women. The study population included 62,494 term singleton mother–infant dyads in the Norwegian Mother and Child Cohort Study (MoBa), a national prospective cohort study in Norway from 1999 to 2008. The association between SSC consumption and BW was assessed using multiple regression analyses with adjustment for potential confounders. Each 100 ml intake of SSC was associated with a 7.8 g (95% confidence interval [CI]: −10.3 to −5.3) decrease in BW, a decreased risk of BW > 4,500 g (odds ratio [OR]: 0.94, 95% CI: 0.90 to 0.97) and a near significantly increased risk of BW < 2,500 g (OR: 1.05, 95% CI: 0.99 to 1.10). The negative association with SSC consumption was aggravated by smoking, lack of exercise, and obesity. For mothers with gestational diabetes mellitus, we observed an increased risk of BW > 4,500 g (OR: 1.18, 95% CI: 1.00 to 1.39) and a trend towards significant increase in mean BW (25.1 g, 95% CI: −2.0 to 52.2) per 100 ml SSC. Our findings suggest that increasing consumption of rapidly absorbed sugar from SSC had opposite associations with BW in normal pregnancies and pregnancies complicated by gestational diabetes mellitus.

Exercise during pregnancy and risk of cesarean delivery in nulliparous women: a large population-based cohort study

BACKGROUND

Vaginal delivery for the first birth is of great importance for further obstetric performance for the individual woman. Given the rising cesarean delivery rates worldwide over the past decades, a search for modifiable factors that are associated with cesarean delivery is needed. Exercise may be a modifiable factor that is associated with type of delivery, but the results of previous studies are not conclusive.

OBJECTIVE

The purpose of this study was to investigate the association between exercise during pregnancy and cesarean delivery, both acute and elective, in nulliparous women.

STUDY DESIGN

We conducted a population-based cohort study that involved 39,187 nulliparous women with a singleton pregnancy who were enrolled in the Norwegian Mother and Child Cohort Study between 2000 and 2009. All women answered 2 questionnaires in pregnancy weeks 17 and 30. Acute and elective cesarean delivery data were obtained from the Medical Birth Registry of Norway. Information on exercise frequency and type was assessed prospectively by questionnaires in pregnancy weeks 17 and 30. Generalized linear models estimated risk differences of acute and elective cesarean delivery for different frequencies and types of exercise during pregnancy weeks 17 and 30. We used restricted cubic splines to examine dose-response associations of exercise frequency and acute cesarean delivery. A test for nonlinearity was also conducted.

RESULTS

The total cesarean delivery rate was 15.4% (n=6030), of which 77.8% (n=4689) was acute cesarean delivery. Exercise during pregnancy was associated with a reduced risk of cesarean delivery, particularly for acute cesarean delivery. A nonlinear association was observed for exercise frequency in weeks 17 and 30 and risk of acute cesarean delivery (test for nonlinearity, P=.003 and P=.027, respectively). The largest risk reduction was observed for acute cesarean delivery among women who exercised >5 times weekly during weeks 17 (-2.2%) and 30 (-3.6%) compared with nonexercisers (test for trend, P<.001). Reporting high impact exercises in weeks 17 and 30 was associated with the greatest reduction in risk of acute cesarean delivery (-3.0% and -3.4%, respectively).

CONCLUSION

Compared with nonexercisers, regular exercise and high-impact exercises during pregnancy are associated with reduced risk of having an acute cesarean delivery in first-time mothers.

Predicting who fails to meet the physical activity guideline in pregnancy: a prospective study of objectively recorded physical activity in a population-based multi-ethnic cohort

BACKGROUND

A low physical activity (PA) level in pregnancy is associated with several adverse health outcomes. Early identification of pregnant women at risk of physical inactivity could inform strategies to promote PA, but no studies so far have presented attempts to develop prognostic models for low PA in pregnancy. Based on moderate-to-vigorous intensity PA (MVPA) objectively recorded in mid/late pregnancy, our objectives were to describe MVPA levels and compliance with the PA guideline (≥150 MVPA minutes/week), and to develop a prognostic model for non-compliance with the PA guideline.

METHODS

From a multi-ethnic population-based cohort, we analysed data from 555 women with MVPA recorded in gestational week (GW) 28 with the monitor SenseWear™ Pro3 Armband. Predictor variables were collected in early pregnancy (GW 15). We organized the predictors within the domains health, culture, socioeconomic position, pregnancy, lifestyle, psychosocial factors, perceived preventive effect of PA and physical neighbourhood. The development of the prognostic model followed several steps, including univariate and multiple logistic regression analyses.

RESULTS

Overall, 25 % complied with the PA guideline, but the proportion was lower in South Asians (14 %) and Middle Easterners (16 %) compared with Westerners (35 %). Among South Asians and Middle Easterners, 35 and 28 %, respectively, did not accumulate any MVPA minutes/week compared with 18 % among Westerners. The predictors retained in the prognostic model for PA guideline non-compliance were ethnic minority background, multiparity, high body fat percentage, and perception of few physically active friends. The prognostic model provided fair discrimination between women who did vs. did not comply with the PA guideline.

CONCLUSION

Overall, the proportion who complied with the PA guideline in GW 28 was low, and women with ethnic minority background, multiparity, high body fat percentage and few physically active friends had increased probability of non-compliance. The prognostic model showed fair performance in discriminating between women who did comply and those who did not comply with the PA guideline.

Recreational Physical Activity and Differentiated Thyroid Cancer Risk: A Pooled Analysis of Two Case-Control Studies

PURPOSE

Physical activity has been hypothesized to influence cancer occurrence through several mechanisms. To date, its relation with thyroid cancer risk has been examined in relatively few studies. We pooled 2 case-control studies conducted in Cuba and Eastern France to assess the relationship between self-reported practice of recreational physical activity since childhood and thyroid cancer risk.

METHODS

This pooled study included 1,008 cases of differentiated thyroid cancer (DTC) matched with 1,088 controls (age range 9-35 and 17-60 years in the French and Cuban studies, respectively). Risk factors associated with the practice of recreational physical activity were estimated using OR and 95% CI. Logistic regressions were stratified by age class, country, and gender and were adjusted for ethnic group, level of education, number of pregnancies for women, height, BMI, and smoking status.

RESULTS

Overall, the risk of thyroid cancer was slightly reduced among subjects who reported recreational physical activity (OR = 0.8; 95% CI 0.5-1.0). The weekly frequency (i.e. h/week) seems to be more relevant than the duration (years).

CONCLUSION

Long-term recreational physical activity, practiced since childhood, may reduce the DTC risk. However, the mechanisms whereby the DTC risk decreases are not yet entirely clear.

Pre-pregnant body mass index and recreational physical activity: effects on perinatal mortality in a prospective pregnancy cohort

OBJECTIVE

To examine the effect of maternal pre-pregnant body mass index (BMI) and recreational physical activity on perinatal mortality.

DESIGN

A prospective cohort study.

SETTING

The Norwegian Mother and Child Cohort (MoBa), 1999-2008.

POPULATION

Singleton pregnancies without congenital anomalies (n = 77 246).

METHODS

Pre-pregnant BMI was classified as underweight (<18.5), normal weight (18.5-24.9), overweight (25-29.9), obese (30-34.9) or morbidly obese (BMI ≥ 35). Risk estimates were obtained by logistic regression and adjusted for confounders.

MAIN OUTCOME MEASURES

Perinatal death (stillbirth ≥ 22 weeks plus early neonatal death 0-7 days after birth).

RESULTS

An increased risk of perinatal death was seen in obese [odds ratio (OR) 2.4, 95% CI (confidence interval) 1.7-3.4] and morbidly obese women (OR 3.3, 95% CI 2.1-5.1) as compared with normal weight women. In the group participating in recreational physical activity during pregnancy, obese women had an OR of 3.2 (95% CI 2.2-4.7) for perinatal death relative to non-obese women. In the non-active group the corresponding OR was 1.8 (95% CI 1.1-2.8) for obese women compared with non-obese women. The difference in perinatal mortality risk related to obesity between the active and non-active groups was statistically significant (P-value for interaction = 0.046, multiplicative model).

CONCLUSIONS

Maternal obesity was associated with a two- to three-fold increased risk of perinatal death when compared with normal weight. For women with a BMI <30 the lowest perinatal mortality was seen in those performing recreational physical activity at least once a week.

Recreational Exercise Before and During Pregnancy in Relation to Plasma C-Reactive Protein Concentrations in Pregnant Women

BACKGROUND

Pregnant women who are physically active have a lower risk of preeclampsia and gestational diabetes than women who are less active. One possible mechanism is a reduction in low-grade inflammation, as measured by plasma concentrations of C-reactive protein (CRP). The association between exercise and CRP in pregnant women, however, has not been adequately investigated.

METHODS

A total of 537 pregnant women, enrolled around the 17th week of gestation in the Norwegian Mother and Child Cohort Study in 2003 to 2004, were studied. Self-reported recreational exercise was recalled for both 3 months before pregnancy and early pregnancy. The total energy expenditure from recreational exercise (total recreational exercise, metabolic equivalent of task [MET]-hr/week) was estimated, and low-, moderate- and vigorous-intensity exercise was defined. Plasma CRP concentrations were measured during pregnancy.

RESULTS

In adjusted linear regression models, mean CRP concentration was 1.0% lower [95% CI = -1.9% to 0.2%] with each 1 MET-hr/week of total recreational exercise before pregnancy. In addition, vigorous-intensity exercise before pregnancy was more strongly related to a reduction in CRP levels than low- or moderate-intensity exercise. However, we observed no association between recreational exercise during pregnancy and plasma CRP levels.

CONCLUSIONS

Recreational exercise before pregnancy, especially vigorous exercise, may reduce the risk of maternal inflammation during pregnancy.

Objectively recorded physical activity and the association with gestational diabetes

The aim of this population-based study was to assess the association between objectively recorded physical activity (PA) in early gestation and gestational diabetes mellitus (GDM) identified at 28 weeks of gestation in a multi-ethnic cohort of healthy pregnant women in Oslo, Norway. In total, 759 women were included. In early gestation (<20 weeks), light-, moderate-, and vigorous-intensity PA and number of steps were objectively recorded (SenseWear™ Armband Pro3), and self-reported PA, demographics, and anthropometrics were collected. The 75-g oral glucose tolerance test was performed at 28 weeks of gestation. Women with GDM had fewer objectively recorded steps (mean 7964 steps/day vs 8879 steps/day, P < 0.001) and minutes of moderate-to-vigorous-intensity PA (median 62 min/day vs 75 min/day, P = 0.004) in early gestation than women without GDM. Additionally, 30% of women with GDM compared with 44% (P < 0.001) of women without GDM self-reported regular PA before pregnancy. The significant inverse association between objectively recorded steps per day in early gestation and GDM persisted after adjustment for ethnic origin, weeks of gestation, age, parity, pre-pregnancy BMI, early life socioeconomic position, and self-reported regular PA before pregnancy. The adjusted odds ratio for GDM decreased 19% per standard deviation (3159 steps) increase in objectively recorded steps per day (P = 0.039). Daily life PA in early gestation measured as steps/day was associated with lower risk of GDM.

Physical activity during pregnancy and language development in the offspring

BACKGROUND

In rodents, physical activity during pregnancy has been associated with improved learning and memory in the offspring. We used data from the Avon Longitudinal Study of Parents and Children (born in 1991-92) to investigate maternal physical activity during pregnancy and offspring language development.

METHODS

At 18 weeks of gestation, women reported the hours per week they participated in 11 leisure-time physical activities and the hours per week spent in general physical activity (leisure, household and occupational). Caregivers completed a modified MacArthur Infant Communication scale at 15 months. Verbal intelligence quotient (IQ) was measured at age 8 years. Regression analysis was used to examine the associations of physical activity with MacArthur score (more than 75th percentile) and verbal IQ. The number of participants available for analyses ranged from 4529 to 7162.

RESULTS

Children of women in the two highest quintiles of leisure activity (compared with no leisure activity) were more likely to have high 15-month MacArthur scores (adjusted odds ratio 1.2 [95% confidence interval 0.9, 1.4] and adjusted odds ratio 1.4 [95% CI 1.1, 1.7], respectively). Leisure activity was not associated with IQ, while general physical activity was linked with lower verbal IQ (1 and 3 points lower for the two highest quintiles).

CONCLUSIONS

The most robust finding was a transient increase in offspring vocabulary score at young ages with maternal leisure activity. Differences in the associations with leisure-time physical activity compared with general physical activity need further exploration.

Effect of intensive counselling on physical activity in pregnant women at high risk for gestational diabetes mellitus. A clinical study in primary care

OBJECTIVE

The level of physical activity (PA) of pregnant women in Finland is unknown. Even more limited is our knowledge of PA of women at high risk for gestational diabetes mellitus (GDM).

METHODS

The women (n=54) were randomly assigned to a lifestyle intervention group (n=27) including exercise advice by a physiotherapist six times during pregnancy or to a control group (n=27) without additional exercise advice. Outcomes of the present study were required sample size, timing of counselling and change of PA. PA was retrospectively reported during 12 months before pregnancy and recorded one week monthly during pregnancy.

RESULTS

Individualized counselling by a physiotherapist resulted in small changes of recreational PA (2.7 MET hours/week, p=0.056) up to gestational week 25 compared with the similar decreasing tendency of PA in the control group. The women decreased recreational PA after week 30. Sample size of 550 women at high risk for GDM per group would be needed for a PA study.

CONCLUSIONS

The optimal time window for increasing PA must be earlier than in the last trimester of pregnancy. Sample size for a study to increase PA by 2.7 MET hours/week on pregnant women at high risk of GDM should be about 550 per group.

Physical activity and pregnancy: past and present evidence and future recommendations

PURPOSE

In this review, we provide researchers and practitioners with an overview of the physical activity and pregnancy literature to promote prenatal physical activity, improve measurement, further elucidate the role of activity in reducing maternal health complications, and inform future research.

METHOD

We examined past and present physical activity and pregnancy studies and highlight key papers with a focus on maternal health outcomes to best inform physical activity promotion efforts.

RESULTS

We discuss: (a) historical overview of prenatal physical activity relative to the physical activity guidelines, how they have changed over time, and how evidence of the effect of prenatal activity on maternal/fetal health outcomes has affected clinical recommendations; (b) existing tools and challenges associated with measuring prenatal physical activity; (c) empirical evidence on multilevel determinants of prenatal activity to guide future intervention work; (d) empirical evidence of prenatal activity on adverse maternal outcomes (gestational diabetes mellitus, preeclampsia, excessive gestational weight gain) from observational and intervention studies; and (e) summary/recommendations for future research and practice.

CONCLUSIONS

The physical activity and pregnancy literature has evolved over the past 50 years, and there is sufficient empirical evidence to support the promotion of moderate-to-vigorous prenatal physical activity for maternal health benefits. Future studies and interventions should be carefully designed, theoretically driven, and include validated and reliable activity measures. Researchers and practitioners should also consider the multifaceted determinants and outcomes of prenatal physical activity and intervene to promote physical activity before, during, and after pregnancy.

Validation and responsiveness of the AQuAA for measuring physical activity in overweight and obese pregnant women

OBJECTIVES

The aim of this study was to assess the validity and responsiveness of the self-report Activity Questionnaire for Adults and Adolescents for use in overweight and obese pregnant women.

DESIGN

Longitudinal study with measurements at 17, 24 and 32 weeks of pregnancy.

METHODS

Overweight and obese pregnant women (n=55) were asked to wear an accelerometer (Actigraph model ActiTrainer) and fill out the AQuAA at 17, 24 and 32 weeks of pregnancy. AQuAA outcomes were compared with objective accelerometer data. With accelerometer data, different cut-off points of counts per minute were used to define light, moderate and vigorous physical activities. Spearman correlation coefficients were used to assess evidence for construct validity and responsiveness.

RESULTS

Compared with the accelerometer, time spent in moderate and vigorous physical activities was higher according to the questionnaire, while time spent in sedentary activity was lower. The correlations between AQuAA and accelerometer data were small, regardless of which cut-off point for intensity was used.

CONCLUSIONS

Overweight and obese pregnant women overestimated the time spent in physical activities and underestimated the time spent in sedentary behaviours. The construct validity and responsiveness of the AQuAA compared to an accelerometer was poor for these overweight and obese pregnant women.

Review of self-reported physical activity assessments for pregnancy: summary of the evidence for validity and reliability

BACKGROUND

Epidemiological studies and surveillance systems of pregnant women often rely on collection of physical activity through self-report. This systematic review identified and summarised self-reported physical activity assessments with evidence for validity and reliability among pregnant women.

METHODS

Peer-reviewed articles published through 2011 were included if they assessed validity and/or reliability of an interviewer- or self-administered physical activity questionnaire or diary among pregnant women.

RESULTS

We identified 15 studies, including 12 studies that assessed questionnaires and 4 studies that assessed diaries, conducted in Australia, Finland, Norway, the U.K., the U.S. and Vietnam. For questionnaires, 92% (11/12) assessed mode, all assessed frequency and/or duration and 58% (7/12) collected information on perceived intensity. All but one study (92%) assessed validity of the questionnaires. Questionnaires compared with objective measures (accelerometers, pedometers) ranged from slight to fair agreement, while comparison with other self-reported measures ranged from substantial to almost perfect agreement. Five studies (42%) assessed test-retest reliability of the questionnaires, ranging from substantial to almost perfect agreement. The four studies on diaries were all assessed for validity against objective measures, ranging from slight to substantial agreement.

CONCLUSIONS

Selection of valid and reliable physical activity measures that collect information on dose (type, frequency, duration, intensity) is recommended to increase precision and accuracy in detecting associations of physical activity with maternal and fetal outcomes.

Prepregnancy maternal body mass index and preterm delivery

OBJECTIVE

The purpose of this study was to determine the influence of maternal prepregnancy body mass index on preterm delivery (PTD), controlling for health and lifestyle variables.

STUDY DESIGN

Prospective data were from 83,544 pregnancies in the Norwegian Mother and Child Cohort Study. PTD was divided into early PTD (22 + 0 to 31 + 6 weeks' gestation) and late PTD (32 + 0 to 36 + 6 weeks' gestation).

RESULTS

The overall prevalence of PTD was 5.1%. Increased body mass index was associated with an increased risk of PTD; adjusted odds ratio (aOR) ranged from 1.11 (95% confidence interval [CI], 1.03-1.20) for preobesity to 2.00 (95% CI, 1.48-2.71) for grade-III obesity in the group that included all PTD subgroups. Grade-III obese women had an increased risk of both early and late PTD: aOR, 3.24 (95% CI, 1.71-6.14) and 1.81 (95% CI, 1.29-2.54), respectively.

CONCLUSION

Prepregnancy maternal overweight increases the risk of both early and late PTD.

Maternal Recreational Exercise during Pregnancy in relation to Children's BMI at 7 Years of Age

Exposures during fetal life may have long-term health consequences including risk of childhood overweight. We investigated the associations between maternal recreational exercise during early and late pregnancy and the children's body mass index (BMI) and risk of overweight at 7 years. Data on 40,280 mother-child pairs from the Danish National Birth Cohort was used. Self-reported information about exercise was obtained from telephone interviews around gestational weeks 16 and 30. Children's weight and height were reported in a 7-year follow-up and used to calculate BMI and overweight status. Data was analyzed using multiple linear and logistic regression models. Recreational exercise across pregnancy was inversely related to children's BMI and risk of overweight, but all associations were mainly explained by smoking habits, socioeconomic status, and maternal pre-pregnancy BMI. Additionally, we did not find exercise intensity or changes in exercise habits in pregnancy related to the children's BMI or risk of overweight.

Maternal health and lifestyle, and caries experience in preschool children. A longitudinal study from pregnancy to age 5 yr

In this study, associations were explored between maternal health and lifestyle during pregnancy and in early motherhood, and preschool children's caries experience. The study was based on the Norwegian Mother and Child Cohort Study conducted by the Norwegian Institute of Public Health and on data from the Public Dental Services. A total of 1348 children were followed from pregnancy to age 5 yr. A clinical dental examination was performed at age 5 yr. Questionnaires were completed by the mothers during pregnancy and in the first 18 months of their child's life, and as part of the dental examination. Results from the multivariate logistic regression analysis showed that having an obese mother (OR = 2.3, 95% CI: 1.3-4.1), a mother who consumed a diet containing more fat (OR = 1.6, 95% CI: 1.1-2.5) or sugar (OR = 1.5, 95% CI: 1.1-2.3) than recommended, a mother with low education (OR = 1.5, 95% CI: 1.1-2.3) or one or both parents of non-western origin (OR = 5.4, 95% CI: 2.8-10.6) were statistically significant risk indicators for caries experience at age 5 yr. In conclusion, maternal weight and intake of sugar and fat in pregnancy were associated with caries experience in preschool children. These characteristics may enable early referral to the dental services and preventive care to be delivered.

Measuring physical activity among pregnant women using a structured one-week recall questionnaire: evidence for validity and reliability

Background

Accurate measurement of the components of physical activity during pregnancy can aid in our understanding of the dose response relationships between physical activity and corresponding perinatal outcomes. The aim of this study was to develop and evaluate a one-week recall questionnaire to assess moderate to vigorous physical activity during pregnancy.

Methods

To assess concurrent-related validity, 177 pregnant women (median 18 weeks' gestation, interquartile range (IQR) 15 -23) kept a structured diary and wore an accelerometer (Actigraph) for one week. At the conclusion of the week, they completed the Pregnancy Infection and Nutrition 3 (PIN3) physical activity questionnaire over the telephone. To assess evidence for test-retest reliability, 109 pregnant women (median 19 weeks' gestation, IQR 18-27) completed the questionnaire twice over the telephone, within 48 hours apart, recalling the same two time periods. Spearman correlation coefficients (SCC) and intraclass correlation coefficients (ICC) were used to assess evidence for validity and reliability, respectively.

Results

Comparison of the questionnaire to the structured diary was moderate to substantial (SCC 0.47 to 0.69) for several measures of moderate or vigorous physical activity using either perceived or absolute intensity. Comparison of moderate to vigorous physical activity from the questionnaire (absolute intensity using MET-hours/week) to the accelerometer ranged from 0.12 to 0.23 using SCC for absolute intensity (MET-hours/week) and 0.28 to 0.34 using relative intensity (hours/week) (n = 177). Test-retest reliability was moderate to almost perfect for moderate to vigorous physical activity, with the ICC ranging from 0.56 to 0.82 for both perceived and absolute intensities.

Conclusions

The PIN3 one-week recall questionnaire assessed moderate to vigorous physical activity in the past week with evidence for reliability and validity.