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Biomedical subjects

M Hedegaard

Publications and source records attributed to M Hedegaard.

At least 37 records · Page 2Linked to original sources
PubMed1995

Bias in studies of preterm and postterm delivery due to ultrasound assessment of gestational age.

Ultrasound measurement of fetal dimensions is widely used for estimating gestational age. A little-discussed limitation of this method is that variations in fetal size at a given stage of pregnancy are converted to differences in gestational age. Factors that affect pregnancy duration often affect fetal size also. We explore how the effect of such factors may be biased when gestational age is determined by ultrasound. We selected 3,606 women with singleton pregnancies (1989-1991) who had an early ultrasound measurement of fetal biparietal diameter (BPD) and a good-quality history of last menstrual period (LMP). Using the two measures of gestational age, we estimated risk of preterm and postterm delivery for female babies vs males and for smoking women vs nonsmoking women. There was a 13% excess of preterm delivery among female babies when gestational age was determined by ultrasound, but no excess when gestational age was defined by LMP. For postterm delivery, female babies had a 19% lower risk with ultrasound-defined age, but no deficit with LMP-defined age. We found a similar bias with ultrasound in the analysis of maternal smoking. Thus, factors that reduce fetal size inflate the risk of preterm delivery and deflate the risk of postterm delivery when gestational age is based on ultrasound measurement of the fetus. This bias can distort the relative risk of preterm or postterm delivery by 10-20%.

Adult↗
PubMed1995

Standing at work and preterm delivery.

OBJECTIVE: Guidelines in some European countries and the United States suggest that pregnant women should avoid prolonged standing and heavy lifting in the workplace during the second and third trimester of pregnancy. However, results from epidemiological studies on this topic are ambiguous. The aim of this study was to evaluate the influence of standing and walking at work in the second trimester on preterm delivery in a population with a low frequency of other workplace hazards. SUBJECTS AND DESIGN: A prospective cohort of 8711 women with singleton pregnancies was established during 1989 through 1991. Information was collected during the 16th week of pregnancy about medical and obstetrical history, general lifestyle factors and exposures at work. The analyses were restricted to 4259 respondents who worked at the 16th week. Potential confounders and effect modifiers were evaluated by stratification and multivariate analyses. RESULTS: After adjustment for confounders, women standing more than five hours per work day had an odds ratio (OR) for preterm delivery of 1.2 (95% CI 0.6 to 2.4) compared with women standing two hours or less. For walking, the OR was 1.4 (95% CI 0.7 to 2.5). Many women were unable to separate periods of standing from periods of walking; a combined measure of these two exposures was created to reflect exposure intensity. Women who reported more than five hours of both standing and walking had an adjusted OR of 3.3 (95% CI 1.4 to 8.0) compared with women who reported two hours or less on either of the exposures. No adverse effects were seen for lifting or other types of physical exertion. CONCLUSIONS: Our findings suggest that standing and walking at work during the second trimester may present a particular risk for preterm delivery, and workplace guidelines are justified. Further research is needed to address the specific mechanisms by which physical exertion, including standing and walking, might cause preterm delivery.

Cohort Studies↗
PubMed1995

Standing and walking at work and birthweight.

OBJECTIVES: To study the influence of standing and walking at work on birthweight for gestational age. METHODS: A prospective cohort of 8711 women with singleton pregnancies was established (1989-91). Information about medical and obstetrical history, lifestyle factors and work related exposures were collected at 16 gestational weeks. The 4249 respondents who worked during pregnancy formed the basis of the analyses. RESULTS: After adjustment for confounders and gestational age at delivery, infants of women standing > 5 hours per workday had birthweights 49 g lower (95% confidence interval (CI): -108 to 10) than those of women standing < or = 2 hours. Infants of women walking > 2 but < or = 5 hours per workday had higher birthweights (35 g, CI: 8-63) than those of women with both shorter and longer hours of walking per day. Some women were unable to separate periods of standing from walking; a combined measure of these two exposures was created to reflect exposure intensity. Women who reported > 5 hours of both standing and walking had infants with significantly lower birthweight (-119 g, CI: -230 to -8) compared to those of women who reported < or = 2 hours on either of the exposures. CONCLUSIONS: Our study suggests that standing at work affects birthweight. Prolonged hours of walking and standing decrease birthweight for gestational age, whereas some degree of walking seems beneficial in terms of increased birthweight.

Adult↗
PubMed1994

Methods and consequences of changes in use of episiotomy.

OBJECTIVES: To evaluate the use of feedback by graphical profiles of rates of episiotomy and the impact on clinical practice and perineal state after spontaneous vaginal deliveries assisted by midwives with different attitudes towards episiotomy. DESIGN: Observation period in labour ward followed by feedback to midwives about their own and other midwives' use of episiotomies. The periods before and after the intervention were compared. SUBJECTS: All women (n = 3919) delivering during the two periods who had been assisted by one of 30 midwives; each midwife supervised at least 20 deliveries during each period. MAIN OUTCOME MEASURES: Overall rates of episiotomies and indications, incidence of intact perineums, perineal lacerations, and tears of anal sphincter. RESULTS: The overall rate of episiotomy during the observation period was 37.1% (615). During the second period the rate was 6.6% lower (95% confidence interval 3.6% to 9.6%), corresponding to a relative decrease of 17.8% (10.1% to 24.7%). Higher rates of episiotomy during the observation period were associated with larger reductions in the second period. The decrease could be explained by less use of episiotomy in deliveries with rigid perineum or impending perineal tear. Compared with the observation period, in the second period 3.2% more women (0.3% to 6.3%) had an intact perineum after delivery and 3.4% (0.4% to 6.2%) experienced perineal tears. The overall incidence of tears of the anal sphincter remained unchanged. Women had a slightly reduced incidence of tears of the anal sphincter, however, if they were delivered by midwives who reduced a medium or high initial rate of episiotomy and a tendency towards an increased incidence of tears if they were assisted by midwives who reduced low initial rates (around 20%) of episiotomy. CONCLUSIONS: Changes in the use of episiotomy induced by awareness of clinical practice among midwives seem to increase the incidence of parturients with intact perineum without a concomitant rise in tears of the anal sphincter. To avoid the increase of such tears these changes should probably be restricted to midwives with rates of episiotomies above 30%.

Adult↗
PubMed1994

[Strategies for smoking cessation among pregnant women].

Smoking during pregnancy is harmful to the health of the fetus and the newborn. Smoking increases the risk of low birthweight, preterm delivery and perinatal death. In developed countries smoking during pregnancy is regarded as the single most important risk factor for which it is possible to intervene. We reviewed the Scandinavian and English randomized controlled intervention studies directed towards smoking cessation during pregnancy. The intervention studies were classified according to the method of intervention namely antismoking advice, self-help manuals, measurements of smoking dependent chemical factors and multifactorial methods. We conclude that it is possible to reduce smoking during pregnancy only by an efficient and personal effort performed by a committed person towards each pregnant woman.

Clinical Trials as Topic↗
PubMed1994

[Episiotomy and perineal lesions in spontaneous vaginal delivery].

The purpose of the study was to evaluate the influence of mediolateral episiotomy on the perineal state after spontaneous, singleton vaginal deliveries with the foetus in the occiput anterior position. The design was that of a population based, observational study. Two approaches were used in the analyses: Initially, we considered the parturients as quasi-randomised to one of three equally sized groups of midwives with different attitudes towards episiotomy. Secondly, we studied the effect of episiotomy on the state of the anal sphincter, controlling for birth weight, parity, and duration of second stage of labour. The subjects were 2188 pregnant women delivering consecutively, and the main outcome measures were perineal lacerations and tearing of the anal sphincter. Women allocated to the group of midwives with the lowest rate of episiotomy were more likely to have an intact perineum after delivery (OR = 1.8 (1.4-2.2)), had a slight tendency towards more perineal lacerations (OR = 1.3 (1.0-1.5)), but no increased risk of tearing of the anal sphincter, compared with the women allocated to the two groups of midwives with higher frequencies of episiotomy. The second approach showed that episiotomy was related to an increased risk of tearing of the anal sphincter (OR = 2.3 (1.2-4.6)). However, this relation was not found among the group of parturients delivered by the midwives with the lowest rate of episiotomy (22%). Our results encourage a conservative approach to the use of mediolateral episiotomy, and in the light of previous findings, it seems reasonable to suggest that episiotomy should ideally be used in about one in five spontaneous vaginal deliveries.

Adult↗
PubMed1994

[Fish oil supplementation and duration of pregnancy. A randomized controlled trial].

It was hypothesised from previous observational studies in the Faroes and Denmark that dietary marine n-3 fatty acids would prolong the duration of pregnancy and thereby increase the birth weight, by influencing the production of prostaglandins involved in the process of parturition. Five hundred and thirty-three healthy Danish women were randomly assigned in the 30th week of pregnancy to fish oil (2.7 g n-3 fatty acids (4 1-g capsules Pikasol oil) per day), olive oil (4 1-g capsules per day) or no oil supplementation. The three groups differed in mean gestational age at birth (ANOVA, p = 0.006), with the fish oil group ranking highest and the olive oil group lowest. Babies born to women allocated fish oil had on average 4.0 (95% confidence interval 1.5;6.4) days higher gestational age and 107 (95% confidence interval 1;214) g higher weight at birth than babies born to women allocated olive oil; the difference in gestational age depended on the level of fish intake at enrollment, with a low fish intake enhancing the difference. Fish oil supplementation in the third trimester seems to prolong gestation while allowing continued growth of the foetus; this effect seems to explain the difference between the Faroes and Denmark in pregnancy duration.

Adult↗
PubMed1994

The relation between psychosocial job strain, and preterm delivery and low birthweight for gestational age.

BACKGROUND: The aim of this cohort study was to evaluate the relationship between psychosocial job demands and job control during pregnancy and risk of small-for-gestational age (SGA) and preterm delivery. METHODS: We studied 8711 Danish women with singleton pregnancies between 1989 and 1991. Information about medical and obstetric history, general psychosocial and lifestyle factors and occupational exposures were collected at 16 weeks gestation. The analyses were restricted to 3503 respondents who worked at least 30 hours per week during the first trimester. The women's scores on both the job demand and job control questionnaire were initially dichotomized at the median score, and combined into four exposure categories: relaxed jobs (low demands and high control), active jobs (high demands and high control), passive jobs (low demands and low control), and high-strain jobs (high demands and low control). RESULTS: After adjustment for confounders, women with relaxed jobs had the lowest risk of SGA and preterm delivery. Compared to this group the odds ratio (OR) for SGA delivery among women with passive jobs was 1.3 (95% confidence interval [CI]: 0.9-1.9), with high-strain jobs 1.1 (95% CI: 0.7-1.6), and with active jobs 1.1 (95% CI: 0.8-1.7). Compared to women with relaxed jobs, the OR for preterm delivery among women with passive jobs was 1.4 (95% CI: 0.8-2.3), high-strain jobs 1.3 (95% CI: 0.7-2.2) and active jobs 1.2 (95% CI: 0.7-2.2). All risks were consistently increased in women with low job control. The risks were higher for preterm than for SGA deliveries. However, none of the findings were statistically significant. CONCLUSIONS: The influence of work-related psychosocial strain on the risk of SGA and preterm delivery seems to be small in countries with highly developed social support systems and few other work-related hazards.

Adult↗
PubMed1994

Several genetic and environmental factors influence cord blood IgE concentration.

Cord blood samples were collected from a birth cohort of 2631 infants to elucidate the association between genetic and environmental factors and fetal production of IgE. The cord blood IgE values were treated both as a continuous and as a dichotomous variable in the statistical analyses. Multivariate analysis was used to control for confounding factors. Infants with single and biparental atopic heritage had higher IgE concentrations in cord plasma than children of parents without atopy. Multiple logistic regression analysis revealed a significant association to maternal allergic eczema or perennial rhinitis. The cord blood IgE concentration varied with month of birth with peaks in late autumn. This seasonal variation was not related to parental atopic disease. Boys had significantly higher levels of IgE and more often elevated IgE values (> or = 0.5 kU/l) than girls. Alcohol and caffeine consumption by the mothers during pregnancy were both significantly associated with elevated IgE concentration. There was also a relation between mothers prepregnant weight and elevated CB-IgE levels. No significant association was observed between maternal smoking and cord plasma IgE levels. The fact that many factors presumably not related to child allergy seem to influence the regulation of fetal IgE production, could explain the questionable value of cord blood IgE in predicting allergy in childhood.

Alcohol Drinking↗
PubMed1994

Histamine release from cord blood basophils is influenced by plasma IgE concentration, osmolarity, gestational age at birth and atopic disposition.

To characterize the normal values of histamine release from basophil leucocytes in cord blood after stimulation with both IgE-mediating and non-IgE-mediating secretagogues, a population of 1,684 newborn infants was studied using a microfiber-based method for detecting histamine release. A wide variation in anti-IgE and Concanavalin A-induced histamine release in the population was found. An increase in osmolarity in the release media selectively enhanced the maximal IgE-mediated histamine release, in addition to an increase in sensitivity in the dose response for anti-IgE and Concanavalin A. Both anti-IgE and Concanavalin A mediated histamine release were found to be significantly associated with the concentration of IgE in cord blood. Furthermore, an increased sensitivity to the IgE-mediated response and a close correlation between anti-IgE and Concanavalin A histamine release were found in the group of newborns with high IgE levels. Gestational age at birth and histamine release after stimulation with both IgE-mediating, and non-IgE mediating secretagogues were found to be significantly related, thus suggesting a continuing maturation of the human basophil leucocytes in the last weeks of gestation. Parental atopic disposition also affected basophil releasability in cord blood.

Basophils↗
PubMed1994

Employment during pregnancy in relation to risk factors and pregnancy outcome.

OBJECTIVE: To describe the relation of employment status during pregnancy to potential demographic, behavioural and obstetrical risk factors for adverse late pregnancy outcome, as well as the risks of having a preterm delivery and a small for gestational age infant. DESIGN: Cohort study. SETTING: A university hospital. SUBJECTS: Of 8,711 women with singleton pregnancies (1989-91), 5,875 returned questionnaires about risk factors and employment status at 16 and 30 weeks gestation. Of the respondents 5,552 were analysed in five groups: (1) women working throughout pregnancy, (2) women working in the first, but unemployed during the second trimester, (3) women on sick leave in the first and second trimester, (4) women unemployed throughout pregnancy, and (5) students. The association between employment status and having a small for gestational age infant and preterm delivery was evaluated, accounting for other risk factors. RESULTS: Working women and students had the most and unemployed women the least favourable demographic risk factors. Women on sick leave had the least favourable obstetrical and medical history, followed by unemployed women. No clear pattern of the behavioural risk factors was found. Differences in risk of having a small for gestational age infant were a function of parity, smoking and maternal height. Adjustment for these factors plus education yielded a lower risk of preterm delivery in partially unemployed women and higher risk among women on sick leave compared to working women, accounted for by different risks of bleeding in the second and third trimester. CONCLUSIONS: Comparison of pregnancy outcome among women with different work status should consider the differences in risk factor profile. Adjusting for such risk factors, we found no evidence that work per se had any detrimental or beneficial effects on the risk of having a small for gestational age infant or preterm delivery.

Adolescent↗
PubMed1994

Cesarean section in twin pregnancies in two Danish counties with different cesarean section rates.

OBJECTIVE: Based on a comparison of the clinical indications for cesarean section (CS) in two Danish counties and a review of the literature regarding this issue the aim of this study was to discuss possible explanations for variations in CS rates in twin pregnancies. The comparison of indications for CS in twin pregnancies was made between two Danish counties, one with a high and one with a low overall CS rate in twin deliveries, taking into account the distribution of parity, mother's age, gestational age at birth, and birth weight. DESIGN: A population based, historic follow-up study based on antecedent data. SETTING: Two Danish counties, with a CS rate in twin pregnancies of 57% and 28%, respectively. SUBJECTS: All women with twin pregnancies who delivered in 1989 in the two counties. MAIN OUTCOME MEASURES: Comparison of the CS rates in the two counties according to indications and fetal presentation. SECONDARY MEASURES: Perinatal and maternal outcome. RESULTS: The difference in CS rates between the two counties could not be explained by different distributions of background characteristics. Different attitudes were found towards CS in cases with previous CS, with twin A in breech presentation and in cases with vertex-breech deliveries. These differences could explain less than two thirds of the overall 29% (CI: 12-46%) difference in risk of CS between the two counties, indicating more subtle reasons for the discrepancy. No difference between the two counties in perinatal morbidity and mortality was seen. CONCLUSION: In order to understand and discuss regional variations in the use of CSs in twin deliveries the subjects must be addressed in different ways: the unequivocal indications related to fetal presentations and previous CS can be subjected to randomised controlled trials or large scaled follow-up studies regarding maternal and perinatal morbidity and mortality. Other more subtle determinants of the physicians' and the pregnant women's attitude towards CS, however, seem quantitatively important, and these can only be evaluated in observational studies and through discussions.

Adult↗
PubMed1993

Psychological distress in pregnancy and preterm delivery.

OBJECTIVE: To investigate if psychological distress during pregnancy is associated with increased risk of preterm delivery. DESIGN: Prospective, population based, follow up study with repeated measures of psychological distress (general health questionnaire), based on the use of questionnaires. SETTING: Antenatal care clinic and delivery ward, Aarhus University Hospital, Denmark. SUBJECTS: 8719 women with singleton pregnancies attending antenatal care for the initial visit between 1 August 1989 and 30 September 1991; 5872 women (67%) completed all questionnaires. MAIN OUTCOME MEASURE: Preterm delivery. Estimation of gestational age at delivery was mainly based on early ultrasound measurements. RESULTS: In 197 cases (3.6%) the woman delivered prematurely (less than 259 days). A dose-response relation between psychological distress in the 30th week of pregnancy and risk of preterm delivery was found, but distress measured in the 16th week was not related to preterm delivery. Control of confounding was secured by the use of multivariate logistic regression models. Relative risk for preterm delivery was 1.22 (95% confidence interval 0.84 to 1.79) for moderate distress and 1.75 (1.20 to 2.54) for high distress in comparison to low distress. CONCLUSIONS: Psychological distress later in pregnancy is associated with an increased risk of preterm delivery. Future interventional studies should focus on ways of lowering psychological distress in late pregnancy.

Adolescent↗
PubMed1992

Prediction of light-for-gestational age at delivery in twin pregnancies: an evaluation of fetal weight deviation and growth discordance measured by ultrasound.

The purpose of this retrospective study was to evaluate and discuss different ultrasound methods widely used, among other things, as predictors for light-for-gestational age (LGA) in twin pregnancies. The methods evaluated and compared as predictors for LGA at birth were: (1) Difference between twins in biparietal diameter; (2) difference in abdominal diameter; (3) the percentage difference in estimated fetal weight between twins; and (4) estimation of the weight deviation from the expected weight during pregnancy. The study comprised 66 twin pregnancies, examined by ultrasound scanning less than 15 days before delivery. Using Relative Operating Characteristic curves (ROC curves) estimated fetal weight deviation was the most sensitive and specific of the methods. It is stressed that fetal discordance is not the appropriate predictor of LGA at birth in twin pregnancies.

Birth Weight↗
PubMed1992

[Pregnant women's knowledge about HIV and AIDS].

This investigation is based upon information from 820 pregnant women who replied to a questionnaire about AIDS during the period 17.4.1989-14.7.1989. The questions included sources of information, knowledge about routes of infection and risk groups and the extent of spread of infection and disease in the population. 95% agreed to participate. Knowledge had been obtained primarily via the electronic media, while the health services had limited significance. The employment of sources of information depended on age and occupation. Apart from knowledge about the risk involved in breast feeding, the women were, in general, well informed about routes of infection. Knowledge about risk groups and the current extent of spread of infection was, on the the other hand, deficient. Defective knowledge was concentrated in groups which may be characterized by age (less than 24 years) and occupation (trained and untrained workers and the group of "other occupations"). Information obtained from health staff was connected with better knowledge about the extent of spread of infection. The majority of women desired routine information about AIDS in connection with antenatal control. Prophylactic measures should be based, among other things, on knowledge about development in the knowledge in the population and its employment of sources of information, so that specific information may be directed to certain groups of the population by using the most frequently employed and most effective routes of information. The knowledge of population groups, the attitudes and behaviour should be followed continuously.

Acquired Immunodeficiency Syndrome↗
PubMed1992

[Clinical picture of acute pulmonary embolism. Relations to the degree of vascular obstruction].

In 132 consecutive patients treated for pulmonary embolism, duration of symptoms, number of embolic episodes before the diagnosis, circulatory affection (stable circulation (n = 61), reversible shock (n = 60), circulatory collapse (n = 11), electrocardiographic findings and systolic pulmonary pressure (n = 60) were analysed in relation to 1) underlying diseases (orthopedic surgical patients (n = 43), gynecological-abdominal surgical patients (n = 22), preembolic healthy patients (n = 42), miscellaneous medical patients (n = 25)), and 2) the obstruction of the pulmonary vascular bed quantified by a scintigraphic or angiographic score. While embolic score did not differ between the groups of underlying diseases, preembolic healthy patients with deep vein trombosis (n = 30) had longer mean duration of symptoms (14 days), more embolic episodes, (1.7 episode) and higher pulmonary pressure (72 mmHg) than the material on an average with values of 7 days, 0.9 episodes and 57 mmHg, respectively (p less than 0.001). Among patients with reversible shock or circulatory collapse, half had at least one previous embolic episode, one fifth from two to four. Embolic score correlated well with the circulatory affection (p less than 0.001). A high pulmonary pressure correlated with long duration of symptoms and a high number of embolic episodes (p less than 0.002). Sinus tachycardia and electrocardiographic signs of acute right ventricular strain (complete and incomplete right bundle branch block, SIQIIITIII-pattern and inverted T-waves in V2-4) correlated positively to the circulatory affection and inversely to duration of symptoms and number of embolic episodes (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗