M. Karen Campbell

Neonatal morbidity associated with late preterm and early term birth: the roles of gestational age and biological determinants of preterm birth

BACKGROUND The aim of this study was to elucidate the role of gestational age in determining the risk of neonatal morbidity among infants born late preterm (34-36 weeks) and early term (37-38 weeks) compared with those born full term (39-41 weeks) by examining the contribution of gestational age within the context of biological determinants of preterm birth. METHODS This was a retrospective cohort study. The sample included singleton live births with no major congenital anomalies, delivered at 34-41 weeks of gestation to London-Middlesex (Canada) mothers in 2002-11. Data from a city-wide perinatal database were linked with discharge abstract data. Multivariable models used modified Poisson regression to directly estimate adjusted relative risks (aRRs). The roles of gestational age and biological determinants of preterm birth were further examined using mediation and moderation analyses. RESULTS Compared with infants born full term, infants born late preterm and early term were at increased risk for neonatal intensive care unit triage/admission [late preterm aRR=6.14, 95% confidence interval (CI) 5.63, 6.71; early term aRR=1.54, 95% CI 1.41, 1.68] and neonatal respiratory morbidity (late preterm aRR=6.16, 95% CI 5.39, 7.03; early term aRR=1.46, 95% CI 1.29, 1.65). The effect of gestational age was partially explained by biological determinants of preterm birth acting through gestational age. Moreover, placental ischaemia and other hypoxia exacerbated the effect of gestational age on poor outcomes. CONCLUSIONS Poor outcomes among infants born late preterm and early term are not only due to physiological immaturity but also to biological determinants of preterm birth acting through and with gestational age to produce poor outcomes.

The impact of maternal depressive symptoms on health-related quality of life in children with epilepsy: a prospective study of family environment as mediators and moderators.

Purpose:  To examine the impact of maternal depressive symptoms (DS) on health‐related quality of life (HRQL) in children with new‐onset epilepsy and to identify family factors that moderate and mediate this relationship during the first 24 months after epilepsy diagnosis.

Factors Influencing Full Breastfeeding in a Southwestern Ontario Community: Assessments at 1 Week and at 6 Months Postpartum

Factors associated with full breastfeeding (FBF) at 1 week and at 6 months postpartum were examined in a cohort of 856 mother-infant dyads. Questionnaires were mailed at 4 time points over the first 6 months postpartum. At 1 week, 68% of infants were FBF; at 6 months, 23% were FBF. Factors significantly associated with FBF at 1 week were hospital of delivery, residing with a smoker, maternal shiftwork during pregnancy, and having no prior breast-feeding experience. Cox proportional hazards regression analysis showed that residing with a smoker, having consumed caffeine during pregnancy, reporting elevated maternal trait anxiety at 1 week postpartum, having been employed full-time outside the home prior to delivery, and having received anesthesia/analgesia during labor/delivery were associated with earlier cessation of FBF, whereas not having previous breastfeeding experience predicted its continuation. Although most mothers are breastfeeding early on, a number of factors adversely affect its successful continuation.

Socioeconomic status and non-fatal injuries among Canadian adolescents: variations across SES and injury measures

BackgroundWhile research to date has consistently demonstrated that socioeconomic status (SES) is inversely associated with injury mortality in both children and adults, findings have been less consistent for non-fatal injuries. The literature addressing SES and injury morbidity among adolescents has been particularly inconclusive. To explore potential explanations for these discrepant research findings, this study uniquely compared the relationship across different measures of SES and different causes of injury (recreation versus non-recreation injuries) within a sample of Canadian adolescents.MethodsThe sample included adolescent participants (aged 12 to 19 years) in the Canadian 1996–1997 cross-sectional National Population Health Survey (n = 6967). Five SES measures (household income, two neighbourhood-level proxy measures, two parental indicators) were examined in relation to three injury outcomes (total, recreation, and non-recreation injuries) using multivariable logistic regression.ResultsAmong males, a clear relationship with injury was observed only for a parental SES index, which was positively associated with total and recreation injuries (odds ratios for the highest versus lowest SES category of 1.9 for total and 2.5 for recreation injuries). Among females, there was some evidence of a positive relationship between SES and injuries, particularly for a neighbourhood-level education measure with total and recreation injuries (odds ratios of 1.7 for total and 2.0 for recreation injuries).ConclusionThe results suggest that differences related to the measures of SES chosen and the causes of injury under study may both contribute to discrepancies in past research on SES and non-fatal injuries among adolescents. To clarify the potential SES-injury relationship among youth, the findings emphasize a need for a greater understanding of the meaning and relevance of different SES measures for adolescents, and for an exploration of the pathways through which SES may be related to injury risk.

Prevalence and trajectories of depressive symptoms in mothers of children with newly diagnosed epilepsy.

Purpose:  To examine the prevalence, trajectories, and predictors of depressive symptoms (DS) in mothers of children with new‐onset epilepsy.

Higher zinc intake buffers the impact of stress on depressive symptoms in pregnancy.

Prenatal depression is a public health concern. This studys objectives are to model associations involving dietary zinc intake, psychosocial stress, and sociodemographic factors as they interrelate in the development of depressive symptoms in a cohort of pregnant women from London, Ontario (Prenatal Health Project). We hypothesized that (1) psychosocial stress is intermediate in the causal pathway between sociodemographic factors and zinc intake and that (2) zinc intake serves as a partial mediator between sociodemographic factors, psychosocial stress, and the development of depressive symptoms. Depressive symptoms were measured using the Center for Epidemiologic Studies Depression Scale (CES-D). Psychosocial stress was measured by validated scales and summarized into a composite score. Zinc intake was quantified from food frequency questionnaire and nutrient supplement data. Regression methods were used. The Baron and Kenny method was applied to test mediation hypotheses. Stress-zinc interaction terms were added to the regression model predicting CES-D score to test a possible moderating role for zinc. Our analyses showed that social disadvantage, higher stress, and lower zinc intake were associated with higher CES-D score. Every 1-point increase in stress score was associated with a 1-point increase in CES-D score. Being in the lowest quintile of zinc intake was associated with a 1-point increase in CES-D score; although not clinically meaningful, the association was robust. Evidence was not in favor of the mediation hypotheses, but showed instead that zinc intake moderated the association between stress and depressive symptoms; being in the highest zinc quintile appeared to buffer the impact of stress.

A prospective study of diagnostic conversion of major depressive disorder to bipolar disorder in pregnancy and postpartum

The aim of the present study was to determine the rate of, and risk factors for, a change in diagnosis from major depressive disorder to bipolar disorder, and from bipolar II disorder to bipolar I disorder in pregnancy and postpartum.

Management of premature rupture of membranes at term: Randomized trial

OBJECTIVE We hypothesize that expectant management in the presence of premature rupture of membranes at term would result in a lower cesarean birth rate with no increase in maternal, fetal, or neonatal infection. STUDY DESIGN Term patients who consented to the study were randomly allocated either to expectant management for 48 hours or to induction of labor 8 hours after premature rupture of membranes. Premature rupture of membranes was confirmed by sterile speculum examination of the vagina. Patients randomized to expectant management were transferred to antenatal care and were not examined vaginally until they went into labor. Patients randomized to induction of labor had induction with oxytocin 8 hours after premature rupture of membranes. RESULTS Two hundred sixty-two patients were randomized to the expectant management and induction of labor groups. The cesarean birth rate and the clinical diagnosis of postpartum endometritis was not significantly different in the two groups. Pathologic diagnosis of chorioamnionitis and funisitis, however, was significantly greater in the expectant management group (p < 0.05). Eight of the 15 babies with funisitis were admitted to the neonatal intensive care unit for therapy (two in the induction of labor group and six in the expectant management group, p < 0.05). CONCLUSION Expectant management did not reduce the incidence of cesarean birth and increased the pathologic diagnosis of funisitis and newborn requirements for neonatal intensive care.

The effect of physical activity on adult obesity: Evidence from the Canadian NPHS panel

Although physical activity has been considered as an important modifiable risk factor for obesity, the empirical evidence on the relationship between physical activity and obesity is mixed. Observational studies in the public health literature fail to account for time-invariant unobserved heterogeneity and dynamics of weight, leading to biased estimation of the effect of physical activity on obesity. To overcome this limitation, we propose dynamic fixed-effects models to account for unobserved heterogeneity bias and the dynamics of obesity. We use nationally representative longitudinal data on the cohort of adults aged 18-50 years in 1994/95 from Canadas National Population Health Survey and followed them over 16 years. Obesity is measured by BMI (body mass index). After controlling for a wide range of socio-economic factors, the impact of four alternative measures of leisure-time physical activity (LTPA) and work-related physical activity (WRPA) are analyzed. The results show that each measure of LTPA exerts a negative effect on BMI and the effects are larger for females. Our key results show that participation in LTPA exceeding 1.5 kcal/kg per day (i.e., at least 30 min of walking) reduces BMI by about 0.11-0.14 points in males and 0.20 points in females relative to physically inactive counterparts. Compared to those who are inactive at workplace, being able to stand or walk at work is associated with a reduction in BMI in the range of 0.16-0.19 points in males and 0.24-0.28 points in females. Lifting loads at workplace is associated with a reduction in BMI by 0.2-0.3 points in males and 0.3-0.4 points in females relative to those who are reported sedentary. Policies aimed at promotion of LTPA combined with WRPA like walking or climbing stairs daily would help reduce adult obesity risks.

Classification Efficiency of Multinomial Logistic Regression Relative to Ordinal Logistic Regression

Abstract Classification procedures are useful for the prediction of a response (or outcome) as a result of knowledge of the levels of one or more independent (or predictor) variables. The procedure is said to classify the (possibly multivariate) observation to a level of the response variable. An example might be the prediction of whether an individual will be well, suffer a nonfatal heart attack, or suffer a fatal heart attack. This prediction might be made on the basis of the levels of various independent variables, such as weight, blood pressure, and serum cholesterol, to name a few. The three response categories of the aforementioned example are ordinal. An example of three nonordered response categories might be as follows: well, death from heart attack, and death from cancer. There is some recent interest in ordinal classification procedures. It is reasonable to assume that, when the response variable is ordinal, inclusion of ordinality in the classification model to be estimated should improve mode...