Lanay M. Mudd

Maternal levels of dichlorodiphenyl-dichloroethylene (DDE) may increase weight and body mass index in adult female offspring

Objectives: To investigate the effect of prenatal exposure to polychlorinated biphenyls (PCBs) and dichlorodiphenyl-dichloroethylene (DDE) on weight, height and body mass index (BMI) in adult female offspring of the Michigan fisheater cohort examined between 1973 and 1991. Methods: 259 mothers from the Michigan fisheater cohort were studied. Prenatal exposure to PCBs and DDE was estimated by extrapolating maternal measurements to the time that the women gave birth. 213 daughters aged 20–50 years in 2000 were identified and 83% of them participated in at least one of two repeated investigations in 2001/02 (n = 151) and 2006/07 (n = 129). To assess the effect of prenatal PCB and DDE exposure on anthropometric measurements, generalised estimating equations nested for repeated measurements (2001/02 and 2006/07) and for sharing the same mother were used. We controlled for maternal height and BMI and for daughters’ age, birth weight, having been breastfed and number of pregnancies. Results: Maternal height and BMI were significant predictors of the daughters’ height, weight and BMI. Low birth weight (<2500 g) was significantly associated with reduced adult offspring weight and BMI. The weight and BMI of adult offspring were statistically significantly associated with the extrapolated prenatal DDE levels of their mothers. Controlling for confounders and compared to maternal DDE levels of <1.503 μg/l, offspring BMI was increased by 1.65 when prenatal DDE levels were 1.503–2.9 μg/l and by 2.88 if levels were >2.9 μg/l. Prenatal PCB levels showed no effect. Conclusion: Prenatal exposure to the oestrogenic endocrine-disrupting chemical DDE may contribute to the obesity epidemic in women.

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 womens 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.

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: <10th percentile, Referent: 10th–<70th percentile, High: ≥70th 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.

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.

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.

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 Childrens 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 Childrens Study will have to address potential resistance to research among pregnant women.

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.

Physical activity recommendations: an alternative approach using energy expenditure.

UNLABELLED Most adults do not meet the American College of Sports Medicine and Centers for Disease Control and Prevention (ACSM/CDC) physical activity recommendations. Even fewer meet the more extreme Institute of Medicine (IOM) physical activity recommendations. Compliance with either recommendation has been conventionally assessed by combining frequencies and durations of self-reported activities. Leisure-time energy expenditure is a cumulative measure of activity that offers an alternative method of defining compliance. PURPOSES To calculate the leisure-time energy expenditure of adults complying with the ACSM/CDC or the IOM physical activity recommendations determined by conventional measures and to reexamine compliance with the IOM recommendation using energy expenditure criteria. METHODS National, cross-sectional data from the 2000 Behavioral Risk Factor Surveillance System determined the mode, frequency, and duration of up to two leisure-time activities performed by adults. Four mutually exclusive activity groups (Non-, Low-, ACSM/CDC-, and IOM-Active) were defined on the basis of frequencies and durations of reported activities. Leisure-time energy expenditure (kcal x kg(-1) x wk(-1)) was calculated per respondent. The energy expenditure threshold for meeting the IOM recommendation was calculated as 21 kcal x kg(-1) x wk(-1). RESULTS Of the 162,669 respondents included in the analyses, 29.9% were Nonactive, whereas 42.3%, 23.3%, and 4.5% were Low-, ACSM/CDC-, and IOM-Active, respectively. Median leisure-time energy expenditure values were 9.0, 27.4, and 63.0 kcal x kg(-1) x wk(-1) for Low-, ACSM/CDC-, and IOM-Active groups, respectively. When using energy expenditure criteria, compliance with the IOM recommendation rose to 27.7% of respondents. CONCLUSIONS Compliance with the IOM physical activity recommendation dramatically increased when assessed by energy expenditure compared with conventional criteria, thereby highlighting the potential bias of conventional methods. A significant proportion of adults meet the intent but not the letter of the IOM activity recommendation.

Association of age at menarche with adult leg length and trunk height: Speculations in relation to breast cancer risk

Abstract Background: It seems paradoxical that both increased height and earlier age at menarche (which predicts for shorter stature) are both associated with increased breast cancer risk. Methods: Retrospective data from a parental cohort coupled with prospective interviews with and anthropometric measurements from their daughters were used. Multivariable linear regression analyses were conducted using mixed regression models to account for same-family participants. Results: Controlling for birth weight, maternal height, and birth cohort, and analyzed as a group, a 1—year increase in the age at menarche predicted an increase in standing height, leg length, and trunk height of 0.76, 0.41, and 0.35 cm, respectively. However, when stratifying by birth year (prior to 1966 vs 1966 or after), these relationships were true only for those born prior to 1966. Conclusion: Given the height–breast cancer risk association, the emerging evidence linking breast cell proliferation to hormones associated with growth, and the finding in this study that the relationship between age at menarche and adult height no longer exists for women born in 1966 or later, it is possible that the long-established relationship between age at menarche and breast cancer risk may also no longer exist.

Comparison of Activity Type Classification Accuracy from Accelerometers Worn on the Hip, Wrists, and Thigh in Young, Apparently Healthy Adults

ABSTRACT The purpose of this article is to compare accuracy of activity type prediction models for accelerometers worn on the hip, wrists, and thigh. Forty-four adults performed sedentary, ambulatory, lifestyle, and exercise activities (14 total, 10 categories) for 3–10 minutes each in a 90-minute semi-structured laboratory protocol. Artificial neural networks (ANNs) were developed for four accelerometers (right hip, both wrists, and right thigh,) to predict individual activities and activity categories, with direct observation (DO) as criterion. The wrist-mounted accelerometers achieved the highest accuracy for individual activities (80.9%–81.1%) and activity categories (86.6%–86.7%); accuracy was not different between wrists. The hip-mounted accelerometer had the lowest accuracy (66.2% individual activities, 72.5% activity categories); thigh-mounted accelerometer accuracy (71.4% individual activities, 84.0% activity categories) fell between the wrist- and hip-mounted accelerometers. ANNs developed for accelerometers worn on the wrists and thigh provided high accuracy for activity type prediction and represent a potential approach to physical activity (PA) assessment.