Biomedical subjects

M S Kramer

Publications and source records attributed to M S Kramer.

At least 19 recordsLinked to original sources

PubMed2006

Maternal dietary antigen avoidance during pregnancy or lactation, or both, for preventing or treating atopic disease in the child.

BACKGROUND: Some breastfed infants with atopic eczema benefit from elimination of cow milk, egg, or other antigens from their mother's diet. Maternal dietary antigens are also known to cross the placenta. OBJECTIVES: To assess the effects of prescribing an antigen avoidance diet during pregnancy or lactation, or both, on maternal and infant nutrition and on the prevention or treatment of atopic disease in the child. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (March 2006) and contacted researchers in the field. SELECTION CRITERIA: All randomized or quasi-randomized comparisons of maternal dietary antigen avoidance prescribed to pregnant or lactating women. We excluded trials of multimodal interventions that included manipulation of the infant's diet other than breast milk or of nondietary aspects of the infant's environment. DATA COLLECTION AND ANALYSIS: We extracted data from published reports, supplemented by additional information received from the trialists we contacted. MAIN RESULTS: The evidence from four trials, involving 334 participants, does not suggest a protective effect of maternal dietary antigen avoidance during pregnancy on the incidence of atopic eczema during the first 18 months of life. Data on allergic rhinitis or conjunctivitis, or both, and urticaria are limited to a single trial each and are insufficient to draw meaningful inferences. Longer-term atopic outcomes have not been reported. The restricted diet during pregnancy was associated with a slightly but statistically significantly lower mean gestational weight gain, a nonsignificantly higher risk of preterm birth, and a nonsignificant reduction in mean birthweight.The evidence from one trial, involving 26 participants, did not observe a significant protective effect of maternal antigen avoidance during lactation on the incidence of atopic eczema during the first 18 months.One crossover trial involving 17 lactating mothers of infants with established atopic eczema found that maternal dietary antigen avoidance was associated with a nonsignificant reduction in eczema severity. AUTHORS' CONCLUSIONS: Prescription of an antigen avoidance diet to a high-risk woman during pregnancy is unlikely to reduce substantially her child's risk of atopic diseases, and such a diet may adversely affect maternal or fetal nutrition, or both. Prescription of an antigen avoidance diet to a high-risk woman during lactation may reduce her child's risk of developing atopic eczema, but better trials are needed. Dietary antigen avoidance by lactating mothers of infants with atopic eczema may reduce the severity of the eczema, but larger trials are needed.

Allergens↗

PubMed2006

Aerobic exercise for women during pregnancy.

BACKGROUND: Physiological responses of the fetus (especially increase in heart rate) to single, brief bouts of maternal exercise have been documented frequently. Many pregnant women wish to engage in aerobic exercise during pregnancy but are concerned about possible adverse effects on the outcome of pregnancy. OBJECTIVES: The objective of this review was to assess the effects of advising healthy pregnant women to engage in regular aerobic exercise (at least two to three times per week), or to increase or reduce the intensity, duration, or frequency of such exercise, on physical fitness, the course of labour and delivery, and the outcome of pregnancy. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (June 2005), MEDLINE (1966 to 2005 January Week 1), EMBASE (1980 to 2005 January Week 1), Conference Papers Index (earliest to 2005 January Week 1), contacted researchers in the field and searched reference lists of retrieved articles. SELECTION CRITERIA: Acceptably controlled trials of prescribed exercise programs in healthy pregnant women. DATA COLLECTION AND ANALYSIS: Both review authors independently assessed trial quality and extracted data. Study authors were contacted for additional information. MAIN RESULTS: Eleven trials involving 472 women were included. The trials were small and not of high methodologic quality. Five trials reported significant improvement in physical fitness in the exercise group, although inconsistencies in summary statistics and measures used to assess fitness prevented quantitative pooling of results. Seven trials reported on pregnancy outcomes. A pooled increased risk of preterm birth (relative risk 1.82, 95% confidence interval (CI) 0.35 to 9.57) with exercise, albeit statistically nonsignificant, does not cohere with the absence of effect on mean gestational age (weighted mean difference +0.3, 95% CI -0.2 to +0.9 weeks), while the results bearing on growth of the fetus are inconsistent. One small trial reported that physically fit women who increased the duration of exercise bouts in early pregnancy and then reduced that duration in later pregnancy gave birth to larger infants with larger placentas. AUTHORS' CONCLUSIONS: Regular aerobic exercise during pregnancy appears to improve (or maintain) physical fitness. Available data are insufficient to infer important risks or benefits for the mother or infant. Larger and better trials are needed before confident recommendations can be made about the benefits and risk of aerobic exercise in pregnancy.

Exercise↗

PubMed2004

Does previous infection protect against atopic eczema and recurrent wheeze in infancy?

BACKGROUND: Frequent infection in infancy and early childhood has been hypothesized to explain the low prevalence of asthma and other atopic disease among children in developing countries (the so-called 'hygiene hypothesis'), but the low prevalence in Eastern Europe remains unexplained. OBJECTIVE: To test the hygiene hypothesis in the Republic of Belarus by examining the relationship between gastrointestinal (GI) and respiratory infection and two potentially atopic outcomes in the first 12 months of life: atopic eczema and recurrent wheeze. METHODS; We carried out two case-control studies nested within a large (n=17 046) randomized trial in Belarus, with cases defined as (1) first occurrence of atopic eczema (n=819) and (2) second episode of wheezing (n=112). Incidence density sampling was used to select four matched controls born within 1 month at the same hospital as the case. Exposure was defined as one or more episodes of GI or respiratory infection (examined separately) with onset >7 days before onset of the case's atopic outcome. Analyses controlled for family atopic history, duration of exclusive breastfeeding, sex, birth weight, maternal education, and (for recurrent wheeze) maternal smoking. RESULTS: For atopic eczema, prior GI infection occurred in 7.4% of cases vs. 6.0% of controls [adjusted OR=1.27 (0.94-1.72)] and prior respiratory infection in 35.2% vs. 32.6% [adjusted OR=1.14 (95% CI=0.94-1.37)]. For recurrent wheeze, prior GI infection occurred in 9.8% of cases vs. 7.4% of controls [adjusted OR=1.30 (0.60-2.82)]. CONCLUSION: Our results do not support the hypothesis that infection protects against atopic eczema or recurrent wheezing in the first 12 months of life.

Adult↗

PubMed2002

Optimal duration of exclusive breastfeeding.

BACKGROUND: : Although the health benefits of breastfeeding are widely acknowledged, opinions and recommendations are strongly divided on the optimal duration of exclusive breastfeeding. Much of the debate has centered on the so-called 'weanling's dilemma' in developing countries: the choice between the known protective effect of exclusive breastfeeding against infectious morbidity and the (theoretical) insufficiency of breast milk alone to satisfy the infant's energy and micronutrient requirements beyond four months of age. The debate over whether to recommend exclusive breastfeeding for four to six months versus 'about six months' has recently become heated and acrimonious. OBJECTIVES: : The primary objective of this review was to assess the effects on child health, growth, and development, and on maternal health, of exclusive breastfeeding for six months versus exclusive breastfeeding for three to four months with mixed breastfeeding (introduction of complementary liquid or solid foods with continued breastfeeding) thereafter through six months. A secondary objective was to assess the child and maternal health effects of prolonged (greater than six months) exclusive breastfeeding versus exclusive breastfeeding for six months followed by mixed breastfeeding thereafter. SEARCH STRATEGY: : Two independent literature searches were carried out, together comprising the following databases: MEDLINE (as of 1966), Index Medicus (prior to 1966), CINAHL, HealthSTAR, BIOSIS, CAB Abstracts, EMBASE-Medicine, EMBASE-Psychology, Econlit, Index Medicus for the WHO Eastern Mediterranean Region, African Index Medicus, Lilacs (Latin American and Caribbean literature), EBM Reviews-Best Evidence, the Cochrane Database of Systematic Reviews (The Cochrane Library Issue 3, 2000), and the Cochrane Controlled Trials Register (The Cochrane Library Issue 3, 2000). No language restrictions were imposed. The two searches yielded a total of 2,668 unique citations. Contacts with experts in the field yielded additional published and unpublished studies. SELECTION CRITERIA: : We selected all internally-controlled clinical trials and observational studies comparing child or maternal health outcomes with exclusive breastfeeding for six or more months versus exclusive breastfeeding for at least three to four months with continued mixed breastfeeding until at least six months. Studies were stratified according to study design (controlled trials versus observational studies), provenance (developing versus developed countries), and timing of compared feeding groups (three to seven months versus later). DATA COLLECTION AND ANALYSIS: : Two reviewers independently assessed study quality (using a priori assessment criteria) and extracted data. MAIN RESULTS: : Twenty independent studies meeting the selection criteria were identified by the literature search: nine from developing countries (two of which were controlled trials in Honduras) and 11 from developed countries (all observational studies). The two trials did not receive high methodologic quality ratings but were nonetheless superior to any of the observational studies included in this review. The observational studies were of variable quality; in addition, their nonexperimental designs were not able to exclude potential sources of confounding and selection bias. Definitions of exclusive breastfeeding varied considerably across studies. Neither the trials nor the observational studies suggest that infants who continue to be exclusively breastfed for six months show deficits in weight or length gain, although larger sample sizes would be required to rule out modest differences in risk of undernutrition. The data are conflicting with respect to iron status, but at least in developing country settings where newborn iron stores may be suboptimal, suggest that exclusive breastfeeding without iron supplementation through six months may compromise hematologic status. Based primarily on an observational analysis of a large randomized trial in Belarus, infants who continue exclusive breastfeeding for six months or more appear to have a significantly reduced risk of one or more episodes of gastrointestinal infection. No significant reduction in risk of atopic eczema, asthma, or other atopic outcomes has been demonstrated in studies from Finland, Australia, and Belarus. Data from the two Honduran trials suggest that exclusive breastfeeding through six months is associated with delayed resumption of menses and more rapid postpartum weight loss in the mother. REVIEWER'S CONCLUSIONS: : We found no objective evidence of a 'weanling's dilemma'. Infants who are exclusively breastfed for six months experience less morbidity from gastrointestinal infection than those who are mixed breastfed as of three or four months, and no deficits have been demonstrated in growth among infants from either developing or developed countries who are exclusively breastfed for six months or longer. Moreover, the mothers of such infants have more prolonged lactational amenorrhea. Although infants should still be managed individually so that insufficient growth or other adverse outcomes are not ignored and appropriate interventions are provided, the available evidence demonstrates no apparent risks in recommending, as a general policy, exclusive breastfeeding for the first six months of life in both developing and developed country settings. Large randomized trials are recommended in both types of setting to rule out small effects on growth and to confirm the reported health benefits of exclusive breastfeeding for six months or beyond.

Breast Feeding↗

PubMed2002

Validation of image analysis for enzyme histochemical and immunocytochemical staining.

Immunocytochemical and enzyme histochemical analyses of cells and tissues are used to detect changes in the extent of injury and the expression of various molecules. Image analysis quantitation offers an easier, more efficient technique to evaluate these changes. We studied the application of image analysis for evaluating enzyme histochemistry and immunocytochemistry of cells and tissues as a way to assess stroke. Using brain sections, we compared investigator and computer-generated image analysis of 2,3,5-triphenyltetrazolium chloride stained cerebral infarcts in rats subjected to 2 h middle cerebral artery occlusion and 22 h re-perfusion. Both methods documented the infarct volumes with a comparison of means of less then 5%. This suggests no difference between computer- and hand-calculated values. Computer-generated analysis was easier and faster to use. Using endothelial cell monolayers, immunocytochemical staining of a time course of heat shock protein expression was compared to a grading system using fast red chromagen counterstained with hematoxylin. Results demonstrated greater ease and efficiency with computer-generated image analysis compared to other subjective systems of analysis. Image analysis is more useful for detecting small differences in staining, especially when using 3,3-diaminobenzidine as a chromagen. Investigator bias is also reduced using this system. Our comparisons validate the use of this versatile technology to assess more easily both cell and tissues in stroke research.

Animals↗

PubMed2001

Detecting and eliminating erroneous gestational ages: a normal mixture model.

In perinatal research and clinical practice, gestational age is a crucial variable for measuring foetal 'growth' (birth weight for gestational age) and for estimating the risk of mortality and morbidity, yet reported gestational age values are affected by random and systematic errors due to the absence of a gold standard measure. Previous investigators have used birth weight (which is measured with greater validity and precision than is gestational age) to correct such errors, but existing methods are inadequate due to unreasonable assumptions about the distributions of birth weight and gestational age. We propose a new method for identifying and correcting implausible observations using the expectation-maximization (EM) algorithm. Using population-based data from U.S. birth certificates, we compare the resulting gestational ages, birth weight distributions at each gestational age, and gestational age-specific infant mortality based on the new method with those on the same population produced by previous published correction methods. The new method gives the best birth weight distributions for gestational age and the most realistic gestational-age-specific mortality rates, while each of the other methods has at least one significant flaw.

Algorithms↗

PubMed2001

Secular trends in congenital anomaly-related fetal and infant mortality in Canada, 1985-1996.

Prenatal diagnosis of major congenital anomalies and subsequent termination of affected pregnancies has been widely available as part of routine obstetric care in recent years. In this study, vital statistical data on stillbirths, live births, and infant deaths were used to examine secular trends in gestational age-specific and category-specific fetal and infant mortality due to congenital anomalies in Canada (excluding Ontario and Newfoundland) from 1985-1996. Comparisons of the rates between 1985-1987 and 1994-1996 were made using relative risks and 95% confidence intervals (CI). The overall fetal mortality rate due to congenital anomalies increased significantly, from 68.0 per 100,000 total births in 1985-1987 to 78.6 per 100,000 total births in 1994-1996, while the overall infant mortality rate due to congenital anomalies decreased significantly over the same period, from 2.47 to 1.79 per 1,000 live births. The fetal death rate due to congenital anomalies at 20-21 weeks of gestation increased approximately five-fold (relative risk [RR] = 4.83, 95% CI = 3.28-7.11) from 4.5 to 21.5 per 100,000 fetuses at risk, while the rate at 37-41 weeks decreased by 30% (RR = 0.70, 95% CI = 0.50-0.97). Fetal death rates among pregnancies at 20-25 weeks of gestation increased in all categories of congenital anomaly except anencephaly and respiratory system anomalies. Congenital anomaly-related fetal and infant deaths have increased at early gestation but declined at later gestation in Canada. These changes suggest an increase in prenatal diagnosis and selective termination of pregnancies with congenital anomalies in recent years.

Canada↗

PubMed2001

Trends in preterm birth and neonatal mortality among blacks and whites in the United States from 1989 to 1997.

Preterm birth, a major determinant of infant mortality, has been increasing in recent years. The authors examined trends in preterm birth and its determinants by using the US birth and infant death files for 1989-1997. The impact of trends in preterm birth rates on neonatal and infant mortality was also evaluated. Among Whites, preterm births (<37 completed weeks of gestation) increased from 8.8% of livebirths in 1989 to 10.2% in 1997, a relative increase of 15.6%. On the other hand, preterm births among Blacks decreased by 7.6% (from 19.0% to 17.5%) during the same period. An increase in obstetric interventions contributed to increases in preterm births for both races but was outweighed by other unidentified favorable influences for Blacks. Neonatal mortality among preterm Whites dropped 34% during the 8 years of the study, while the decrease was only 24% among Blacks. This large disparity countered the changes in preterm birth rates so that the percentage decline in neonatal mortality was similar in the two racial groups (18-20%). In conclusion, the anticipated mortality benefit from a lower preterm birth rate for Blacks has been blunted by suboptimal improvement in mortality among the remaining preterm infants. The widening race gap in mortality among preterm infants merits attention.

Black or African American↗

PubMed2001

Pacifier use, early weaning, and cry/fuss behavior: a randomized controlled trial.

CONTEXT: The World Health Organization and the United Nations Children's Fund strongly discourage use of pacifiers because of their perceived interference with breastfeeding. Observational studies have reported a strong association between pacifier use and early weaning, but such studies are unable to determine whether the association is causal. OBJECTIVES: To test whether regular pacifier use is causally related to weaning by 3 months postpartum and to examine differences in results according to randomized intervention allocation vs observational use or nonuse of pacifiers. DESIGN: Double-blind, randomized controlled trial conducted from January 1998 to August 1999. SETTING: Postpartum unit of a university teaching hospital in Montreal, Quebec. PARTICIPANTS: A total of 281 healthy, breastfeeding women and their healthy, term singleton infants. INTERVENTIONS: Participants were randomly allocated to 1 of 2 counseling interventions provided by a research nurse trained in location counseling. The experimental intervention (n = 140) differed from the control (n = 141) by recommending avoidance of pacifier use and suggesting alternative ways to comfort a crying or fussing infant. MAIN OUTCOME MEASURES: Early weaning, defined as weaning within the first 3 months, compared between groups; 24-hour infant behavior logs detailing frequency and duration of crying, fussing, and pacifier use at 4, 6, and 9 weeks. RESULTS: A total of 258 mother-infant pairs (91.8%) completed follow-up. The experimental intervention increased total avoidance of pacifier use (38.6% vs 16.0% in the control group), reduced daily use (40.8% vs 55.7%), and decreased the mean number of pacifier insertions per day (0.8 vs 2.4 at 4 weeks [P<.001]; 0.8 vs 3.0 at 6 weeks [P<.001]; and 1.3 vs 3.0 at 9 weeks [P =.004]). In the analysis based on randomized intervention allocation, the experimental intervention had no discernible effect on weaning at 3 months (18.9% vs 18.3% in the experimental vs control group; relative risk [RR], 1.0; 95% confidence interval [CI], 0.6-1.7), and no effect was observed on cry/fuss behavior (in the experimental vs control groups, respectively, total daily duration, 143 vs 151 minutes at 4 weeks [P =.49]; 128 vs 131 minutes at 6 weeks [P =.81]; and 110 vs 104 minutes at 9 weeks [P =.58]). When randomized allocation was ignored, however, we observed a strong observational association between exposure to daily pacifier use and weaning by 3 months (25.0% vs 12.9% of the exposed vs unexposed groups; RR, 1.9; 95% CI, 1.1-3.3). CONCLUSIONS: We found a strong observational association between pacifier use and early weaning. No such association was observed, however, when our data were analyzed by randomized allocation, strongly suggesting that pacifier use is a marker of breastfeeding difficulties or reduced motivation to breastfeed, rather than a true cause of early weaning.

Breast Feeding↗

PubMed2001

Comparison of maternal and infant outcomes between vacuum extraction and forceps deliveries.

The authors conducted a population-based historical cohort study in the Canadian province of Quebec to assess the maternal and infant outcomes associated with vacuum extraction and forceps deliveries. The study database contains information on 305,391 mother-infant dyads (linked by a common institutional code and hospital chart number) for singleton live vaginal births with a nonbreech presentation at the gestational age of 37 or more completed weeks and a birth weight between 2,500 and 4,000 g during fiscal years 1991/1992 to 1995/1996. Of the births, 31,015 were delivered by vacuum extraction, and 18,727 were delivered by forceps. Compared with delivery by forceps, the adjusted risk ratios for third-/fourth-degree perineal laceration, intracranial hemorrhage, subdural or cerebral hemorrhage, intraventricular hemorrhage, subarachnoid hemorrhage, cephalhematoma, and neonatal in-hospital death were 0.48 (95% confidence interval: 0.45, 0.50), 1.28 (95% confidence interval: 0.73, 2.25), 0.97 (95% confidence interval: 0.49, 1.93), 0.99 (95% confidence interval: 0.16, 5.97), 5.44 (confidence interval: 1.26, 23.43), 2.02 (95% confidence interval: 1.89, 2.16), and 0.93 (95% confidence interval: 0.32, 2.70), respectively. The authors conclude that vacuum extraction causes less maternal trauma but may increase the risk of cephalhematoma and certain types of intracranial hemorrhage (e.g., subarachnoid hemorrhage).

Adult↗

PubMed2001

Implausible birth weight for gestational age.

Various rules have been proposed to identify and exclude live births with implausible values of birth weight for gestational age from large perinatal data sets. The authors carried out a preliminary evaluation of common rules by examining the frequency and nature of rule-based exclusions among live births in Canada (excluding Ontario) between 1992 and 1994. There were 625 (0.09%), 133 (0.02%), 170 (0.02%), and 2,858 (0.40%) live births identified for exclusion by a median birth weight for gestational age +/-4 standard deviations (SD) rule, a +/-5 SD rule, a rule based on expert clinical opinion, and a modification of Tukey's rule, respectively. The birth weight and gestational age distribution of the exclusions depended on the particular rule used; for example, 12.1% and 0.3% of live births of > or =4,500 g were excluded under Tukey's rule and the rule based on expert opinion, respectively. Infant mortality rates among those excluded were 8-13 times higher than among all live births. Current rules for identifying implausible birth weight for gestational age tend to flag live births at high risk for infant death. Such rules may erroneously attenuate temporal trends in important perinatal outcomes.

Algorithms↗

PubMed2001

Socio-economic disparities in preterm birth: causal pathways and mechanisms.

Preterm birth is the leading cause of infant mortality in industrialised societies. Its incidence is greatly increased among the socially disadvantaged, but the reasons for this excess are unclear and have been relatively unexplored. We hypothesise two distinct sets of causal pathways and mechanisms that may explain social disparities in preterm birth. The first set involves chronic and acute psychosocial stressors, psychological distress caused by those stressors, increased secretion of placental corticotropin releasing hormone (CRH), changes in sexual behaviours or enhanced susceptibility to bacterial vaginosis and chorioamnionitis, cigarette smoking or cocaine use, and decidual vasculopathy. The second hypothesised pathway is a gene-environment interaction based on a highly prevalent mutation in the gene for methylenetetrahydrofolate reductase (MTHFR), combined with low folate intake from the diet and from prenatal vitamin supplements, consequent hyperhomocysteinemia, and decidual vasculopathy. We propose to test these hypothesised pathways and mechanisms in a nested case-control study within a prospectively recruited and followed cohort of pregnant women with singleton pregnancies who deliver at one of four Montreal hospitals that serve an ethnically and socio-economically diverse population. Following recruitment during the late first or early second trimester, participating women are seen at 24-26 weeks, when a research nurse obtains a detailed medical and obstetric history; administers several scales to assess chronic and acute stressors and psychological function; obtains blood samples for CRH, red blood cell and plasma folate, homocysteine, and DNA for the MTHFR mutation; and performs a digital and speculum examination to measure cervical length and vaginal pH and to obtain swabs for bacterial vaginosis and fetal fibronectin. After delivery, each case (delivery at < 37 completed weeks following spontaneous onset of labour or prelabour rupture of membranes) and two controls are selected for placental pathological examination, hair analysis of cotinine, cocaine, and benzoylecgonine, and analysis of stored blood and vaginal specimens. Statistical analysis will be based on multiple logistic regression and structural equation modelling, with sequential construction of models of potential aetiological determinants and covariates to test the hypothesised causal pathways and mechanisms. The research we propose should improve understanding of the factors and processes that mediate social disparities in preterm birth. This improved understanding should help not only in developing strategies to reduce the disparities but also in suggesting preventive interventions applicable across the entire socio-economic spectrum.

Adult↗

PubMed2001

Critical pediatric equipment availability in Canadian hospital emergency departments.

STUDY OBJECTIVE: Of all child visits to emergency departments, 1% to 5% involve critically ill children who require cardiopulmonary resuscitation. Numerous versions of pediatric equipment lists for EDs have been published. Despite these efforts, many EDs remain unprepared for pediatric emergencies. The objectives of this study were to assess the availability of pediatric resuscitation equipment items in Canadian hospital EDs and to identify risk factors for the unavailability of these items. METHODS: Using the updated database of the Canadian Association of Emergency Physicians (CAEP), a questionnaire survey was sent to 737 Canadian hospital EDs with a maximum of 3 mailings to nonresponders. On-site visits to a selected subset of hospital EDs were completed to validate the results obtained by the mailed questionnaire. RESULTS: The response rate was 88.3% (650/737). Results showed the following overall equipment unavailability: intraosseous needle, 15.9%; pediatric drug dose guidelines, 6.6%; infant blood pressure cuff, 14.8%; pediatric defibrillator paddles, 10.5%; infant warming device, 59.4%; infant bag-valve-mask device, 3.5%; infant laryngoscope blade, 3.5%; 3-mm endotracheal tube, 2.5%; and pediatric pulse oximeter, 18.0%. Low percentage of pediatric visits, lack of an on-call pediatrician for the ED, and lack of a pediatric advanced life support-trained physician on staff were independently associated with equipment unavailability. CONCLUSION: This study demonstrated that essential pediatric resuscitation equipment is unavailable in a disturbingly high number of EDs across Canada and has identified several determinants of this unavailability.

Canada↗

PubMed2001

Maternal asthma and pregnancy outcomes: a retrospective cohort study.

OBJECTIVE: We examined the relationship between asthma during pregnancy and selected infant and maternal outcomes. STUDY DESIGN: A retrospective cohort study was conducted on mother-infant dyads identified from a linked infant and maternal hospital discharge database in the Canadian province of Quebec between fiscal years 1991-1992 and 1995-1996. Mothers with asthma (n = 2193) were compared with a randomly selected control sample (n = 8772) from the remaining population of mothers. RESULTS: After important confounding variables were accounted for, maternal asthma was significantly associated with several adverse infant outcomes, including preterm birth and birth of infants who are very small for gestational age, and adverse maternal outcomes, such as idiopathic preterm labor, early idiopathic preterm labor, preeclampsia, transient hypertension of pregnancy, pregnancy-associated hypertension, chorioamnionitis, and cesarean delivery. CONCLUSION: Our results demonstrated that pregnant women with asthma are at substantially increased risk for several adverse infant and maternal outcomes and suggest the need for extra attention to mothers with asthma and their infants.

Abruptio Placentae↗

PubMed2001

A new and improved population-based Canadian reference for birth weight for gestational age.

BACKGROUND: Existing fetal growth references all suffer from 1 or more major methodologic problems, including errors in reported gestational age, biologically implausible birth weight for gestational age, insufficient sample sizes at low gestational age, single-hospital or other non-population-based samples, and inadequate statistical modeling techniques. METHODS: We used the newly developed Canadian national linked file of singleton births and infant deaths for births between 1994 and 1996, for which gestational age is largely based on early ultrasound estimates. Assuming a normal distribution for birth weight at each gestational age, we used the expectation-maximization algorithm to exclude infants with gestational ages that were more consistent with 40-week births than with the observed gestational age. Distributions of birth weight at the corrected gestational ages were then statistically smoothed. RESULTS: The resulting male and female curves provide smooth and biologically plausible means, standard deviations, and percentile cutoffs for defining small- and large-for-gestational-age births. Large-for-gestational age cutoffs (90th percentile) at low gestational ages are considerably lower than those of existing references, whereas small-for-gestational-age cutoffs (10th percentile) postterm are higher. For example, compared with the current World Health Organization reference from California (Williams et al, 1982) and a recently proposed US national reference (Alexander et al, 1996), the 90th percentiles for singleton males at 30 weeks are 1837 versus 2159 and 2710 g. The corresponding 10th percentiles at 42 weeks are 3233 versus 3086 and 2998 g. CONCLUSIONS: This new sex-specific, population-based reference should improve clinical assessment of growth in individual newborns, population-based surveillance of geographic and temporal trends in birth weight for gestational age, and evaluation of clinical or public health interventions to enhance fetal growth. fetal growth, birth weight, gestational age, preterm birth, postterm birth.

Algorithms↗

PubMed2001

Changes in stillbirth and infant mortality associated with increases in preterm birth among twins.

OBJECTIVE: To examine whether the recent substantial increase in preterm birth among twins has been associated with changes in fetal and infant mortality. DESIGN: Cohort study based on information in the linked live birth, stillbirth, and mortality databases of Statistics Canada. SETTING: Ten of 12 provinces and territories in Canada. PARTICIPANTS: All twin live births and stillbirths between 1985 and 1996, along with information on deaths during infancy (1985-1997). MAIN OUTCOME MEASURE: Fetal and infant mortality rates. RESULTS: The rate of preterm birth among twin live births increased significantly by 17% (95% confidence interval: 14%-20%) from 42.5% between 1985 and 1987 to 49.6% between 1994 and 1996. Overall, stillbirth rates among twins declined from 22.4 per 1000 total births in 1985 to 1987 to 18.8 per 1000 total births in 1994 to 1996. Among twin fetuses >/=34 weeks' gestation, stillbirth rates decreased from 9.5 per 1000 in 1985 to 1987 to 5.4 per 1000 fetuses at risk in 1994 to 1996. Infant mortality rates among twin live births declined substantially in all categories of gestational age above 24 weeks except for live births at 32 to 33 and 34 to 36 weeks' gestation. CONCLUSIONS: The recent increase in preterm birth among twins was associated with a substantial reduction in stillbirth rates at and near term gestation. Infant mortality rates declined concurrently, although the absence of a significant decrease in infant mortality among twin live births at 32 to 33 and 34 to 36 weeks' gestational age needs additional scrutiny.

Canada↗

PubMed2001

Maternal smoking and the risk of early weaning: a meta-analysis.

OBJECTIVES: This study reviewed evidence on the effect of maternal smoking on early weaning. METHODS: The following databases and journals were searched: Medline, Scientific Citation Index, Pediatrics, Journal of Pediatrics, New England Journal of Medicine, and Lancet. Analysis was restricted to studies in which infants who had never been breastfed were excluded or the prevalence of breastfeeding initiation was more than 90%. RESULTS: In smoking vs nonsmoking mothers, the random effects odds ratio for weaning before 3 months was 1.93 (95% confidence interval [CI] = 1.55, 2.40). An adjusted odds ratio of 1.50 (95% CI = 1.34, 1.68) was shown in studies that had lost-to-follow-up rates below 15% and included adequate adjustment for confounding. CONCLUSIONS: Maternal smoking increases the risk of early weaning.

Adult↗

PubMed2001

Recent trends in fetal and infant outcomes following post-term pregnancies.

All births and infant deaths in 1985 87 and 1992 94 in Canada, except in Ontario and Newfoundland, were analyzed to assess the potential impact of the recent increased use of elective labour induction for post-term pregnancies. Probabilistic linkage was carried out of infant death records (Canadian Mortality Database) and respective birth registrations (Canadian Birth Database) for the periods 1985 87 and 1992 94. The combined fetal and infant mortality declined by 20 30% between 1985 87 and 1992 94 at each gestational week beginning at 37 weeks, with no increased reduction among post-term pregnancies. Asphyxia-related fetal and infant deaths, the most likely cause of death being preventable by labour induction for post-term pregnancies, did not decrease among post-term pregnancies. In contrary, a substantial decrease of asphyxia-related deaths was observed at 37 and 38 weeks over the same periods of time. Because fetal and infant deaths are rare events and because the number of pregnancies passing 42 weeks of gestation decreased dramatically during 1992 94, statistically unstable results may be inevitable in the comparison of mortality in this group of pregnancies.

Canada↗