Review of impacts of physical activity on maternal metabolic health during pregnancy.

Our purpose was to review relations between physical activity during pregnancy, gestational diabetes, and other maternal metabolic markers (i.e., lipids, tumor necrosis factor alpha (TNFα), interleukin six (IL-6), leptin, and adiponectin). While observational studies indicate a protective effect of physical activity on gestational diabetes, interventions that promote recommended levels of physical activity during pregnancy (i.e., 150+ min/week) have failed to show significant effects. However, interventions have been often underpowered and with low protocol adherence. Maternal lipids, TNFα, IL-6, and leptin all increase and adiponectin decreases with a healthy pregnancy. Although the evidence base is small, preliminary results indicate a beneficial effect of physical activity on lowering triglycerides, TNFα, and leptin levels while increasing muscle-derived IL-6 levels during pregnancy. Future studies are needed to examine relationships among prospectively measured physical activity and metabolic markers throughout pregnancy, as well as theoretically based physical activity interventions to prevent gestational diabetes.

Preeclampsia and diabetes.

Preeclampsia is diagnosed in women presenting with new onset hypertension accompanied by proteinuria or other signs of severe organ dysfunction in the second half of pregnancy. Preeclampsia risk is increased 2- to 4-fold among women with type 1 or type 2 diabetes. The limited number of pregnant women with preexisting diabetes and the difficulties associated with diagnosing preeclampsia in women with proteinuria prior to pregnancy are significant barriers to research in this high-risk population. Gestational diabetes mellitus (GDM) also increases preeclampsia risk, although it is unclear whether these two conditions share a common pathophysiological pathway. Nondiabetic women who have had preeclampsia are more likely to develop type 2 diabetes later in life. Among women with type 1 diabetes, a history of preeclampsia is associated with an increased risk of retinopathy and nephropathy. More research examining the pathophysiology, treatment, and the long-term health implications of preeclampsia among women with preexisting and gestational diabetes is needed.

Maternal mid-pregnancy lipids and birthweight.

OBJECTIVE: To describe associations between maternal lipids and birthweight and to determine whether pre-pregnancy body mass index (BMI) modifies these associations. DESIGN: Cohort study. SETTING: Multiple communities in Michigan, USA. POPULATION: Participants were a sub-cohort of women from the multi-community Pregnancy Outcomes and Community Health (POUCH) study (1998-2004). METHODS: Maternal total cholesterol, high-density lipoprotein (HDLc), and low-density lipoprotein (LDLc) cholesterol, and triglycerides were assessed at 16-27 weeks' gestation. Women were classified as having normal (< 25 kg/m(2) ) or overweight/obese (≥ 25 kg/m(2) ) pre-pregnancy BMI. MAIN OUTCOME MEASURES: Sex- and gestational-age-specific body weight z-score (BWz). RESULTS: Regression models examined associations among lipids (low: 1st quartile, referent: middle quartiles, high: 4th quartile) and BWz for the total sample and stratified by pre-pregnancy BMI. In adjusted analyses (n = 1207), low HDLc was associated with lower BWz (ß = -0.23, 95% CI -0.40 to -0.06), whereas high triglycerides were associated with higher BWz (ß = 0.23, 95% CI 0.06-0.41). Once stratified by pre-pregnancy BMI, low total cholesterol was associated with lower BWz in normal BMI women (ß = -0.25, 95% CI -0.47 to -0.03), whereas in overweight/obese BMI women, high HDLc was inversely (ß = -0.29, 95% CI -0.54 to -0.04) and high triglycerides were directly associated with BWz (ß = 0.32, 95% CI 0.07-0.54). Removing women with gestational diabetes/hypertensive disorders did not alter the results. CONCLUSIONS: The associations between maternal lipids and BWz vary by lipid measure and pre-pregnancy BMI. Future work should examine whether lipids and pre-pregnancy BMI make unique contributions to the fetal programming of disease.

Improving the physical activity and nutrition environment through self-assessment (NAP SACC) in rural area child care centers in North Carolina.

OBJECTIVE: To determine if child care centers in rural, Western North Carolina met recommendations for nutrition and physical activity, if focusing on nutrition and physical activity practices and policies was effective in improving the center environment, and if differences existed between centers affiliated or unaffiliated with schools. METHODS: Of 33 child care centers in three counties, 29 submitted mini-grant requests and participated in a pre-post evaluation using Nutrition and Physical Activity Self-Assessment for Child Care (NAP SACC). NAP SACC assesses compliance for nutrition and physical activity recommendations and standards. Between October 2011 and April 2012, centers participated in workshops and goal setting specific to nutrition and physical activity. RESULTS: At baseline, over 95% of the centers met all recommendations. However, post-intervention, Wilcoxon Signed Ranks Test (p<0.05) indicated significant improvement across center types in five out of 37 nutrition and seven out of 17 physical activity standards following the intervention. Centers unaffiliated with schools made significant changes in ten nutrition standards, while those affiliated with schools improved in only two standards and decreased on one standard. CONCLUSION: Overall, rural child care centers in Western North Carolina were meeting standards, they were still able to strengthen policies and practices by following NAP SACC. This was especially true for centers unaffiliated with schools. Continued financial support may assist centers in sustaining increased physical activity in children.

Attitudes of pregnant women towards collection of biological specimens during pregnancy and at birth.

Epidemiological investigations of maternal and child health may involve the collection of biological specimens, including cord blood and the placenta; however, the attitudes of pregnant women towards participation in the collection of biological specimens have been studied rarely. We evaluated attitudes towards collection and storage of biological specimens, and determined whether attitudes differed by maternal characteristics, in a cross-sectional study of pregnant women residing in Kent County, Michigan. Women were interviewed at their first visit for prenatal care between April and October 2006 (n = 311). Willingness to participate was highest for maternal blood collection (72%), followed by storage of biological specimens (68%), placenta collection (64%), and cord blood collection (63%). About one-quarter of women (25-28% by procedure) would not participate even if compensated. Hispanic ethnicity was associated with unwillingness to participate in maternal blood collection (OR = 2.16 [95% CI 1.15, 4.04]). Primiparity was associated with unwillingness to participate in cord blood collection (OR = 1.72 [95% CI 1.23, 2.42]). Among women willing to participate, Hispanic women were less likely to require compensation; while higher educated, married and primiparous women were more likely to require compensation. In conclusion, while many pregnant women were willing to participate in biological specimen collection, some women were more resistant, in particular Hispanic and primiparous women. Targeting these groups of women for enhanced recruitment efforts may improve overall participation rates and the representativeness of participants in future studies of maternal and child health.

Maternal lipids at mid-pregnancy and the risk of preterm delivery.

OBJECTIVE: This study examined associations between maternal lipid levels at mid-pregnancy and preterm delivery, medically indicated or spontaneous. DESIGN: Prospective cohort study. SETTING: Women were recruited from 52 clinics in five Michigan, USA communities (1998-2004). POPULATION: Pregnant women were enrolled at 15-27 weeks' gestation and followed to delivery (n=3019). METHODS: A single blood sample was obtained at study enrollment. Blood lipids, i.e. total cholesterol (TC), high-density lipoprotein (HDLc), low-density lipoprotein (LDLc) cholesterol, and triglycerides (TG), were measured on a sub-cohort (n=1309). MAIN OUTCOME MEASURES: There were 221 spontaneous, 100 medically indicated preterm deliveries and 988 term deliveries. Polytomous logistic regression models examined relationships among cholesterol levels (Low: <10(th) percentile, Referent: 10(th) -<70(th) percentile, High: ≥70(th) percentile), quartiles of TG (Referent: first quartile) and delivery outcome (Referent: term). RESULTS: Odds of medically indicated preterm delivery were increased among women with low TC (adjusted odds ratio (aOR)=2.04, 95% confidence interval (CI): 1.12, 3.72), low HDLc (aOR=1.89, 95%CI: 1.04, 3.42) or low LDLc (aOR=1.96, 95%CI: 1.09, 3.54). Odds of spontaneous preterm delivery were increased among women with high TC (aOR=1.51, 95%CI: 1.06, 2.15), high LDLc (aOR=1.42, 95%CI: 0.99, 2.04) or high TG (aOR=1.90, 95%CI: 1.21, 2.97 and aOR=1.72, 95%CI: 1.06, 2.78 for third and fourth quartiles, respectively). CONCLUSIONS: Extremely low TC, HDLc, and LDLc were associated with a modest increase in risk of medically indicated preterm delivery, whereas high TC, LDLc and TG modestly increased the risk of spontaneous preterm delivery. Further research is needed to uncover explanations for these associations and to identify optimal ranges for maternal lipids.

Association of available parkland, physical activity, and overweight in America's largest cities.

OBJECTIVE: To examine associations between the densities of available parkland, parkland provided per capita, and levels of physical activity (PA) and overweight in urban United States. DESIGN: Cross-sectional correlation research using data drawn from the Trust for Public Land's 2010 City Park Facts and The Behavioral Risk Factor Surveillance System (BRFSS). City Park Facts is a report containing "basic information on urban park systems--from acreage, to facilities, to staffing, to budgets, to usership, and more" for America's 85 largest cities. The Behavioral Risk Factor Surveillance System is a state-based surveillance system that collects information on health risk behaviors, preventive health practices, and health care access primarily related to chronic disease and injury. SETTING: Sixty-seven metropolitan statistical areas in the United States that provided data for both reports. PARTICIPANTS: Randomly selected adults aged 18 years and older who participated in the 2009 Behavioral Risk Factor Surveillance Survey in the 67 metropolitan statistical areas. MAIN OUTCOME MEASURE(S): Total parkland per acre of metropolitan area was correlated to inactivity, engaging in recommended levels of moderate or vigorous PA, engaging in recommended levels of vigorous PA, and body weight. Parkland acreage per 1000 residents was correlated to these same variables. Multilevel models considered these relationships while controlling for race, family income, and age of respondents and accounting for clustering by metropolitan statistical area. RESULTS: There were significant, positive correlations between park density and PA (r(s) = 0.37, n = 67, P < .01) and between park density and exercise (r(s) = 0.35, n = 67, P < .01), and a negative correlation between park density and being above normal weight (r(s) = -0.32, n = 67, P < .01). Adjusted multilevel models showed that parkland density in the highest versus lowest quartile was associated with significantly higher odds of meeting PA guidelines (aOR = 1.19, 95% CI: 1.08-1.30) and reduced odds of being overweight/obese (aOR = 0.85, 95% CI: 0.76-0.95). CONCLUSIONS: Each of these findings substantiates the need for providing parkland in a community. As such, this research helps to support the notion that the development of a strong park system may lead to positive PA and health outcomes for that community.

Aerobic fitness and physical activity levels of children born prematurely following randomization to postnatal dexamethasone.

OBJECTIVE: To investigate the effects of postnatal dexamethasone treatment on aerobic fitness and physical activity levels in school-aged children born with very low birth weight (VLBW). STUDY DESIGN: This was a follow-up study of 65 VLBW infants who participated in a randomized controlled trial of dexamethasone (DEX) to reduce ventilator dependency. Aerobic fitness was determined from peak oxygen uptake (VO(2peak)) with a cycle ergometer. Habitual physical activity was assessed by questionnaire. RESULTS: A trend for a treatment with an interaction between treatment and of diagnosis of chronic lung disease (CLD) was found, with the children in the placebo group with CLD having the lowest VO(2peak) (P = .09). Reduced fitness was seen in 53% of the group treated with DEX and 48% of the group given placebo. No between-group differences in physical activity were seen. Parental reports suggested that nearly two-thirds of the children participated in < 1 hour per week of vigorous physical activity, which was explained in part by decreased large airway function (r = 0.30; P = .03). CONCLUSIONS: We found no adverse effect of postnatal DEX on aerobic fitness or habitual physical activity at school age. However, the reduced fitness and physical activity levels emphasize the need for closer follow-up and early interventions promoting physical activity to reduce the risk of chronic disease in this at-risk population.

Factors associated with women's perceptions of physical activity safety during pregnancy.

UNLABELLED: Health benefits of physical activity (PA) during pregnancy have been noted, but women's perceptions of PA safety have been little studied. OBJECTIVES: To examine associations among PA participation, safety perceptions, and demographic characteristics. METHODS: Pregnant women were recruited from nine clinics in Grand Rapids, MI (USA) from April to October, 2006. Demographics, participation in moderate and vigorous PA, and perceived safety of both intensities (5-pt Likert scales) were reported. Logistic regression analyses were used to estimate associations. RESULTS: Of 342 eligible women, 296 provided complete PA information. Most (88%) participated in some PA and felt moderate PA was safe (89%), but only 36% felt vigorous PA was safe. Feeling unsafe/unsure about moderate PA was associated with non-White race/ethnicity, low education, low income, not participating in moderate PA, and/or not intending to be active during pregnancy. Hispanic ethnicity, low education, nulliparity, and not participating in moderate or vigorous PA were associated with feeling unsafe/unsure about vigorous PA. CONCLUSIONS: Pregnant women generally feel that moderate PA is safe, but are less certain about vigorous PA. More work is needed to inform pregnant women about the benefits of moderate PA, especially among non-White and low education/income populations.

Attitudes of pregnant women towards participation in perinatal epidemiological research.

We assessed attitudes of a multi-ethnic sample of pregnant women in regard to participation in five data collection procedures planned for use in the National Children's Study. A cross-sectional survey was conducted in nine prenatal clinics in Kent County, Michigan between April and October 2006. Women were approached in clinic waiting rooms at the time of their first prenatal visit and 311 (91.0%) participated. Women were asked about their willingness to participate, and the smallest amount of compensation required for participation in a 45-min in-person interview, a 15-min telephone interview, maternal and infant medical record abstraction, and an infant physical examination. Percentages for willingness to participate were highest for telephone interview (83%), followed by in-person interview (60%), infant examination (57%), and maternal (56%) and infant medical records (54%). About 34-48% of women reported that no compensation would be required for participation by data procedure. Some women reported unwillingness to participate in telephone (9%) or personal (17%) interview, record abstraction (34%) or infant examination (26%), even with compensation. Education greater than high school was associated with increased odds of refusal for infant physical examination, adjusted odds ratio 2.44 [95% confidence interval 1.41, 4.23]. In conclusion, 9-34% of pregnant women, depending on procedure, stated they would not participate in non-invasive research procedures such as medical record abstraction and infant examination, even with compensation. Resistance to these research procedures was especially noted among more highly educated women. Planning for the National Children's Study will have to address potential resistance to research among pregnant women.

Associations Among Work-Related and Leisure-Time Physical Activity With Level of Nausea During Pregnancy.

OBJECTIVE: Pregnancy-induced nausea and vomiting are common maladies during early pregnancy and may be related to physical activity (PA). Our objective was to determine relations among work-related PA (work PA), leisure-time physical activity (LTPA), and nausea during the first trimester. STUDY DESIGN: Online or mailed surveys with questions on pregnancy-related nausea, work PA, and LTPA were completed by 70 women at 15 to 30 months postpartum. Women recalled nausea during the first trimester (none, ≤1 h/d, 2-3 h/d, 4-6 h/d, ≥6 h/d) as well as LTPA frequency, duration, and type. Women also recalled total working hours in their first trimester and percentage of time sitting, standing, and walking at work. RESULTS: A total of 42 women (60%) were categorized as having high nausea (≥2 h/d). Mann-Whitney U tests showed that women with low nausea had significantly more MET minutes per week of LTPA (P = .05) and hours per week spent standing at work (P = .03). Logistic regression analyses showed standing for ≥20 h/wk at work was related to reduced odds of high nausea (adjusted odds ratio = 0.23; 95% CI = 0.06-0.96), whereas meeting LTPA guidelines was nonsignificantly related to reduced odds. CONCLUSION: These findings suggest an inverse relationship between first trimester PA and level of nausea. Further investigation is needed to determine the directionality of these relations.

Evaluation of the activPAL accelerometer for physical activity and energy expenditure estimation in a semi-structured setting.

OBJECTIVES: Evaluate accuracy of the activPAL and its proprietary software for prediction of time spent in physical activity (PA) intensities (sedentary, light, and moderate-to-vigorous) and energy expenditure (EE) and compare its accuracy to that of a machine learning model (ANN) developed from raw activPAL data. DESIGN: Semi-structured accelerometer validation in a laboratory setting. METHODS: Participants (n=41 [20 male]; age=22.0±4.2) completed a 90-min protocol performing 13 activities for 3-10min each and choosing activity order, duration, and intensity. Participants wore an activPAL accelerometer (right thigh) and a portable metabolic analyzer. Criterion measures of time spent in sedentary, light, and moderate-to-vigorous PA were determined using measured MET values of ≤1.5, 1.6-2.9, and ≥3.0, respectively. Estimated times in each PA intensity from the activPAL software and ANN were compared with the criterion using repeated measures ANOVA. Window-by-window EE prediction was assessed using correlations and root mean square error. RESULTS: activPAL software-estimated sedentary time was not different from the criterion, but light PA was overestimated (6.2min) and moderate- to vigorous PA was underestimated (4.3min). ANN-estimated sedentary time and light PA were not different from the criterion, but moderate- to vigorous PA was overestimated (1.8min). For EE estimation, the activPAL software had lower correlations (r=0.76 vs. r=0.89) and higher error (1.74 vs. 1.07 METs) than the ANN. CONCLUSIONS: The ANN had higher accuracy for estimation of EE and PA than the activPAL software in this semi-structured laboratory setting, indicating potential for the ANN to be used in PA assessment.

Wrist-independent energy expenditure prediction models from raw accelerometer data.

PURPOSES: (1) Develop artificial neural network (ANN) models for wrist accelerometer data which can predict energy expenditure (EE) using data collected from either wrist. (2) Develop ANNs for detecting the wrist on which the accelerometer was worn. Forty-four adults wore GENEActiv accelerometers on the left and right wrists and a portable metabolic analyzer while participating in a 90 min semi-structured activity protocol. Participants performed 14 sedentary, lifestyle, exercise, and ambulatory activities and were allowed to choose activity order, duration, and intensity. ANNs were created to predict EE and wrist detection using a leave-one-out cross-validation. In total, 12 combinations of feature sets (mean and variance of raw, vector magnitude, and absolute value data), training methods (left- and right- wrist), and testing methods (left- and right-wrist data) were used to develop EE prediction ANNs. Accuracy of the ANNs was evaluated using correlations, root mean square error (RMSE), and bias, using metabolic analyzer data as the criterion for EE. ANNs using raw data from the same wrist (e.g. EE predicted from right wrist ANNs using accelerometer data from right wrist) had the highest accuracy for EE prediction (r = 0.84, RMSE = 1.25-1.26 METs); conversely, opposite-wrist prediction accuracy (e.g. EE predicted from right wrist ANNs using accelerometer data from left wrist) was lower (r = 0.60-0.64, RMSE = 1.93-2.01 METs). Preprocessing into absolute values prior to ANN development allowed for, high EE prediction accuracy, with no difference in accuracy for same- versus opposite-wrist prediction (r = 0.80-0.83, RMSE = 1.30-1.49 METs). Wrist detection ANNs correctly determined wrist placement 100% of the time. Highly accurate, wrist-independent EE prediction ANNs were developed by computing absolute values of raw acceleration data prior to ANN development. This method provides a potential approach for advancing predictive accuracy of wrist-worn accelerometers.

Validation and Comparison of Accelerometers Worn on the Hip, Thigh, and Wrists for Measuring Physical Activity and Sedentary Behavior.

BACKGROUND: Recent evidence suggests that physical activity (PA) and sedentary behavior (SB) exert independent effects on health. Therefore, measurement methods that can accurately assess both constructs are needed. OBJECTIVE: To compare the accuracy of accelerometers placed on the hip, thigh, and wrists, coupled with machine learning models, for measurement of PA intensity category (SB, light-intensity PA [LPA], and moderate- to vigorous-intensity PA [MVPA]) and breaks in SB. METHODS: Forty young adults (21 female; age 22.0 ± 4.2 years) participated in a 90-minute semi-structured protocol, performing 13 activities (three sedentary, 10 non-sedentary) for 3-10 minutes each. Participants chose activity order, duration, and intensity. Direct observation (DO) was used as a criterion measure of PA intensity category, and transitions from SB to a non-sedentary activity were breaks in SB. Participants wore four accelerometers (right hip, right thigh, and both wrists), and a machine learning model was created for each accelerometer to predict PA intensity category. Sensitivity and specificity for PA intensity category classification were calculated and compared across accelerometers using repeated measures analysis of variance, and the number of breaks in SB was compared using repeated measures analysis of variance. RESULTS: Sensitivity and specificity values for the thigh-worn accelerometer were higher than for wrist- or hip-worn accelerometers, > 99% for all PA intensity categories. Sensitivity and specificity for the hip-worn accelerometer were 87-95% and 93-97%. The left wrist-worn accelerometer had sensitivities and specificities of > 97% for SB and LPA and 91-95% for MVPA, whereas the right wrist-worn accelerometer had sensitivities and specificities of 93-99% for SB and LPA but 67-84% for MVPA. The thigh-worn accelerometer had high accuracy for breaks in SB; all other accelerometers overestimated breaks in SB. CONCLUSION: Coupled with machine learning modeling, the thigh-worn accelerometer should be considered when objectively assessing PA and SB.

The Influence of Risk Perceptions and Efficacy Beliefs on Leisure-Time Physical Activity During Pregnancy.

BACKGROUND: Pregnancy risk perceptions and physical activity efficacy beliefs may facilitate or impede pregnancy leisure-time physical activity (LTPA). We examined the separate and joint influence of these variables on LTPA behavior among pregnant women. METHODS: Pregnant women (n = 302) completed a survey containing questions on LTPA efficacy beliefs and behavior, as well as pregnancy risk perceptions with respect to the health of the unborn baby. As stipulated by the Risk Perception Attitude (RPA) Framework, 4 attitudinal groups were created: Responsive (High Risk+High Efficacy), Proactive (Low+High), Avoidant (High+Low), and Indifferent (Low+Low). Moderate LTPA and vigorous LTPA were dichotomized for study analyses. RESULTS: A total of 82 women (27.2%) met the moderate physical activity guideline and 90 women (30.1%) performed any vigorous LTPA. Responsive and proactive pregnant women (those with high efficacy) were most likely to meet the moderate guideline and participate in vigorous LTPA. Hierarchical logistic regression did not reveal an interactive effect of pregnancy risk perceptions and LTPA efficacy beliefs for meeting the moderate guideline (OR = 0.94, 95% CI = 0.66-1.36) or any vigorous LTPA participation (OR = 1.41, 95% CI = 0.86-2.29). CONCLUSIONS: LTPA efficacy beliefs appear important in facilitating greater levels of pregnancy LTPA. Significant interactive effects between pregnancy risk perceptions and LTPA efficacy beliefs were not found.

Energy Expenditure Prediction Using Raw Accelerometer Data in Simulated Free Living.

PURPOSE: The purpose of this study was to develop, validate, and compare energy expenditure (EE) prediction models for accelerometers placed on the hip, thigh, and wrists using simple accelerometer features as input variables in EE prediction models. METHODS: Forty-four healthy adults participated in a 90-min, semistructured, simulated free-living activity protocol. During the protocol, participants engaged in 14 different sedentary, ambulatory, lifestyle, and exercise activities for 3-10 min each. Participants chose the order, duration, and intensity of activities. Four accelerometers were worn (right hip, right thigh, as well as right and left wrists) to predict EE compared with that measured by the criterion measure (portable metabolic analyzer). Artificial neural networks (ANNs) were created to predict EE from each accelerometer using a leave-one-out cross-validation approach. Accuracy of the ANN was evaluated using Pearson correlations, root mean square error, and bias. Several ANNs were developed using different input features to determine those most relevant for use in the models. RESULTS: The ANNs for all four accelerometers achieved high measurement accuracy, with correlations of r > 0.80 for predicting EE. The thigh accelerometer provided the highest overall accuracy (r = 0.90) and lowest root mean square error (1.04 METs), and the differences between the thigh and the other monitors were more pronounced when fewer input variables were used in the predictive models. None of the predictive models had an overall bias for prediction of EE. CONCLUSIONS: A single accelerometer placed on the thigh provided the highest accuracy for EE prediction, although monitors worn on the wrists or hip can also be used with high measurement accuracy.

Maternal Physical Activity During Pregnancy, Child Leisure-Time Activity, and Child Weight Status at 3 to 9 Years.

BACKGROUND: We sought to evaluate the effects of maternal leisure-time physical activity (LTPA) during pregnancy and current child LTPA on child weight status. METHODS: Women with term pregnancies in the Pregnancy Outcomes and Community Health Study (1998-2004) were followed-up. A race-stratified subset of participants (cohort A) received extensive follow-up efforts leading to better response rates (592/926 = 64%) and diversity. The remainder (Cohort B) had a lower response rate (418/1629 = 26%). Women reported child height, weight and LTPA at 3 to 9 years (inactive vs. active), and recalled pregnancy LTPA (inactive vs. active). A 4-category maternal/child LTPA variable was created (reference: active pregnancy + active child). Children were classified as healthy weight, overweight, or obese using age- and sex-specific Body Mass Index percentiles. Logistic regression was used to assess the odds of child obesity (reference: healthy weight). RESULTS: In unadjusted analyses, pregnancy inactivity increased odds for obesity when the child was active (1.6 [95% CI, 1.0-2.6] in Cohort A; 2.1 [95% CI, 1.1-4.0] in Cohort B), and more so when the child was inactive (2.4 [95% CI, 1.2-4.9] in Cohort A; 3.0 [95% CI, 1.0-8.8] in Cohort B). Adjustment for covariates attenuated results to statistical nonsignificance but the direction of relations remained. CONCLUSIONS: Maternal inactivity during pregnancy may contribute to child obesity risk.

United States birth weight reference corrected for implausible gestational age estimates.

OBJECTIVES: To provide an updated US birth weight for gestational age reference corrected for likely errors in last menstrual period (LMP)-based gestational age dating, as well as means and SDs, to enable calculation of continuous and categorical measures of birth weight for gestational age. METHODS: From the 2009-2010 US live birth files, we abstracted singleton births between 22 and 44 weeks of gestation with at least 1 nonmissing estimate of gestational age (ie, LMP or obstetric/clinical) and birth weight. Using an algorithm based on birth weight and the concordance between these gestational age estimates, implausible LMP-based gestational age estimates were either excluded or corrected by using the obstetric/clinical estimate. Gestational age- and sex-specific birth weight means, SDs, and smoothed percentiles (3rd, 5th, 10th, 90th, 95th, 97th) were calculated, and the 10th and 90th percentiles were compared with published population-based references. RESULTS: A total of 7 818 201 (99% of eligible) births were included. The LMP-based estimate of gestational age comprised 85% of the dataset, and the obstetric/clinical estimate comprised the remaining 15%. Cut points derived from the current reference identified ∼10% of births as ≤10th and ≥90th percentiles at all gestational weeks, whereas cut points derived from previous US-based references captured variable proportions of infants at these thresholds within the preterm and postterm gestational age ranges. CONCLUSIONS: This updated US-based birth weight for gestational age reference corrects for likely errors in gestational age dating and allows for the calculation of categorical and continuous measures of birth size.

Body mass index is associated with appropriateness of weight gain but not leisure-time physical activity during pregnancy.

BACKGROUND: Little is known about how leisure-time physical activity (LTPA) influences gestational weight gain (GWG) among body mass index (BMI) categories. The purpose of this study was to examine the relationship between pregnancy LTPA and the proportion of normal, overweight, and obese women who meet GWG recommendations. METHODS: Participants included 449 subcohort women from the Pregnancy Outcomes and Community Health (POUCH) study. LTPA was collapsed into 3 categories [(None, < 7.5 kcal/kg/wk (low), ≥ 7.5 kcal/kg/wk (recommended)]. GWG was categorized according to IOM recommendations (low, recommended, or excess). Chi-square and logistic regression analyses were used to evaluate relationships among LTPA, BMI, and GWG. RESULTS: Overweight women were more likely to have high GWG vs. normal weight women (OR = 2.3, 95% CI 1.3-4.0). Obese women were more likely to experience low GWG (OR = 7.3, 95% CI 3.6-15.1; vs. normal and overweight women) or excess GWG (OR = 3.5, 95% CI 1.9-6.5; vs. normal weight women). LTPA did not vary by prepregnancy BMI category (P = .55) and was not related to GWG in any prepregnancy BMI category (P = .78). CONCLUSIONS: Regardless of prepregnancy BMI, LTPA did not affect a woman's GWG according to IOM recommendations. Results may be due to LTPA not differing among BMI categories.

Health benefits of physical activity during pregnancy: an international perspective.

While early studies on the effects of leisure time physical activity (LTPA) during pregnancy were concerned about possible harm to the mother or fetus, these fears have not been substantiated. Instead, a growing body of literature has documented several health benefits related to pregnancy LTPA. The purpose of this article was to synthesize evidence from epidemiological studies conducted in the United States, Canada, and Scandinavia on the benefits of LTPA and exercise during pregnancy with regard to maternal health, pregnancy outcomes, and child health. We focused on studies evaluating relations between pregnancy LTPA and gestational diabetes, hypertensive disorders, excessive gestational weight gain, birth weight, timing of delivery, and child body composition. The bulk of evidence supports beneficial effects of pregnancy LTPA on each outcome; however, most previous studies have been observational and used self-reported LTPA at only one or two time points in pregnancy. Limitations of the current knowledge base and suggestions for future research on the health benefits of LTPA during pregnancy are provided.