First Year Of Birth Research Articles

Congenital Heart Disease: Frequency and the Need for Intervention on the First Year of Birth

Congenital heart diseases are described as structural abnormalities of the heart and large vessels which are very important in the heart function and are differently prevalent in many societies. Few studies have been carried out on the prevalence of the congenital heart diseases and the condition of such patients within the first year of their life. In this investigation, the frequency of the neonates suffered from congenital heart diseases and the necessity to do interventional treatment within the first year after their birth have been studied. Methods: In this cohort study, all infants born in 2014 in Kashan city are examined for possible congenital heart diseases through physical and paraclinical examinations. The infants suffering from congenital heart disease were followed up for the necessity of interventional treatment during their first year of life. Findings: The frequency of the congenital heart disease was 1.09 percent. Valvular abnormalities and tetralogy of fallout with 23.1 and 21.8 percent respectively, were the most common congenital heart diseases. Among 78 patients, only 16 infants (20.5%) required early interventional treatment during the first year. Conclusion: In this study, it was found that congenital cardiac diseases are rarely common. Tetralogy of fallout as well as valvular defect was mostly common abnormality that needs early interventional treatments.

Offspring birthweight by gestational age and parental cardiovascular mortality: a population-based cohort study.

To estimate risk of parental cardiovascular disease mortality by offspring birthweight. Population-based cohort study. Norwegian mothers and fathers with singleton births during 1967-2002 were followed until 2009 by linkage to the Norwegian cause of death registry. Hazard ratios by offspring absolute birthweight in grams and birthweight adjusted for gestational age (z-score) were calculated using Cox regression and adjusted for parental age at delivery and year of first birth. Stratified analyses on preterm and term births were performed. Maternal and paternal cardiovascular mortality. We followed 711726 mothers and 700212 fathers and found a strong link between maternal cardiovascular mortality and offspring birthweight but only slight evidence of associations in fathers. Adjusting birthweight for gestational age (by z-score) uncovered an unexpected strong association of large birthweight (z-score>2.5) with mothers' cardiovascular mortality (hazard ratio 3.0, 95% CI 2.0-4.6). This risk was apparently restricted to preterm births. In stratified analyses (preterm and term births) hazard ratios for maternal cardiovascular mortality were 1.5 (1.03-2.2) for large preterm babies and 0.9 (0.7-1.2) for large term babies (P-value for interaction=0.02), using normal weight preterm and term, respectively, as references. Women having large preterm babies are at increased risk of both diabetes and cardiovascular mortality. The birth of a large preterm baby should increase clinical vigilance for onset of diabetes and other cardiovascular disease risk factors. Birth of a large preterm baby should increase vigilance for cardiovascular-disease risk factors.

Congenital Heart Disease: Frequency and the Need for Intervention on the First Year of Birth

Congenital Heart Disease: Frequency and the Need for Intervention on the First Year of Birth

Rapamycin enhances survival in a Drosophila model of mitochondrial disease.

Pediatric mitochondrial disorders are a devastating category of diseases caused by deficiencies in mitochondrial function. Leigh Syndrome (LS) is the most common of these diseases with symptoms typically appearing within the first year of birth and progressing rapidly until death, usually by 6-7 years of age. Our lab has recently shown that genetic inhibition of the mechanistic target of rapamycin (TOR) rescues the short lifespan of yeast mutants with defective mitochondrial function, and that pharmacological inhibition of TOR by administration of rapamycin significantly rescues the shortened lifespan, neurological symptoms, and neurodegeneration in a mouse model of LS. However, the mechanism by which TOR inhibition exerts these effects, and the extent to which these effects can extend to other models of mitochondrial deficiency, are unknown. Here, we probe the effects of TOR inhibition in a Drosophila model of complex I deficiency. Treatment with rapamycin robustly suppresses the lifespan defect in this model of LS, without affecting behavioral phenotypes. Interestingly, this increased lifespan in response to TOR inhibition occurs in an autophagy-independent manner. Further, we identify a fat storage defect in the ND2 mutant flies that is rescued by rapamycin, supporting a model that rapamycin exerts its effects on mitochondrial disease in these animals by altering metabolism.

Epidemiologic characterization of sudden infant death syndrome in relation to climate factors and air pollution in Korea: a case-crossover study

Key words: sudden infant death syndrome, time-series, PM10, temperature Background & Aim Sudden infant death syndrome(SIDS) is an unexplained death of a baby within first year of birth. Although cause is unknown, studies suggest that environmental factors including weather and airborne particulate matter (PM) may be associated with infantile fatality. We conducted this study to estimate the effect of climate factors and air pollutants exposure on infantile death in Korea. Method Case-crossover study was performed to assess the temporal association of infantile death with potential environmental factors. SIDS cases from national mortality database from Statistics Korea was matched with 24-hr averages of the air quality indexes and meteorological indexes from the nearest monitoring post from 2007 to 2013, nationwide. Logistic regression was applied to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Result The total number of cases of SIDS in the 7 years was 588, the biggest cases of death was reported from Gyeonggi-do Province (n=135, 22.9%). Most of deaths happened in spring season(n=171; 29.0%), which shows the highest concentration of PM10. OR was 0.97 (95% CI, 0.96-0.99) for an 1℃ increase in 24-hr average of temperature and 1.05 (95% CI, 0.97-1.11) for a10μg/m3 increase in 24-hr average of PM10. Conclusion This study supports that lower temperature and higher PM10 level can be risk factors for SIDS.

Effect of Moving to a Newly Built or Renovated House on Atopic Dermatitis in Korean children: The ISAAC Phase III Study in Korea

Introduction:The prevalence of non-infectious diseases, especially allergic diseases, have been increased. In accordance with the development of economy, the number of people living in newly built houses increased. In previous studies, the positive association between moving to a new house and rhinitis and allergic rhinitis was reported. The aim of this study is to find out the association between moving to a newly built or renovated house during the first year of birth and atopic dermatitis(AD) in Korean children. Methods:Based on the International Study of Asthma and Allergies in Childhood Study (ISAAC) in Korea (2010-2011), we analysed 4,003 1st grade elementary school students who had available data on ISAAC questionnaires, skin prick test result and doctor's inspection reports. AD was defined in a students who had self-reported symptoms within the last 12 months, positive findings in doctor's inspection, and positive skin prick test results. The association was analyzed by using Multiple logistic regression. We used sex, age, parents' academic ability and family history as covariates in our model. Statistical analyses were performed using R ver 3.1.3. Results:Among 4,003 participants, 129 (6.6%) children turned out to be positive for AD.67 (7.0%) children were boys and 62 (6.2%) children were girls. At the time of research, the prevalence of AD of children who had lived in newly built or renovated house within the first year of their birth was 29.7%,and that of children who did not was 16%. In multiple logistic regression model, we found a significant association between them after adjusting for covariates (the crude odds ratio (OR) =2.22, 95%CI:1.49 – 3.32, adjusted OR = 2.07, 95%CI: 1.34 – 3.21). Conclusion:We found a significant association between living in a newly built or renovated house and AD. Further longitudinal epidemiologic study will be needed to get more strong scientific evidence of this association.

한국 후천적 시각장애인의 우울과 영향요인에 관한 연구

본 연구의 목적은 후천적 시각장애인에 대한 우울 실태와 이들의 우울에 영향을 미치는 요인을 규명하는 것으로 이를 위해 본 연구에서는 장애인실태조사 2014 자료를 활용하여 분석을 실시하였다. 연구대상자는 출생 1년 이후부터 시각장애를 가지게 된 20~60세 사이의 성인이며 최종 분석에 포함된 대상자 수는 235명이다. 다중로지스틱회귀분석 실시 결과, 후천적 시각장애인의 약 20%가 우울증상을 경험한 것으로 나타났으며, 우울증상 경험을 예측하는 요인으로는 인구사회학적 요인 중에서는 연령, 성별, 결혼여부가 유의한 요인으로 나타났으며 건강 관련 요인으로는 흡연여부, 일상생활 스트레스 수준, 주관적 건강상태가 유의한 요인으로 파악되었다. 장애관련 요인으로는 장애기간 및 일상생활 수행능력 수준이 유의한 예측요인으로 밝혀졌다. 종합적으로 본 결과는 국내 거주하는 후천적 성인 시각장애인의 많은 수가 우울과 같은 심리적 어려움에 노출되어 있으며, 이를 위한 예방 및 개입 방안 마련이 시급함을 알려준다. 아직까지 장애인 복지 및 장애인 대상 서비스 분야에서 이들에 대한 관심 및 서비스 마련이 미흡한만큼 추후 중도에 실명 혹은 시각손실을 경험하게 된 장애인에 대한 제도적인 고려가 요구된다. This study was designed to examine the depressive symptoms of individuals who became visually impaired and identify factors associated with the symptom. For the analysis, data from the Korean National Survey of Individuals with Disability 2014 was used. Adults between the ages of 20 and 60 years who became visually impaired after the first year of birth were included with a total of 235 individuals in the final sample. To identify the determinants of their depressive symptoms, a multivariate logistic regression analysis was conducted. The results showed that about twenty percent of the respondents reported having depressive symptoms in the past year. Among the sociodemographic factors, age, gender, and marital status were identified as significant predictors, while smoking status, stress level, and self-reported health status were identified as important health-related predictors. Among the disability-related factors, the length of disability and activities of daily living level were found to be significantly associated with the likelihood of experiencing the symptom. The results indicate the need for practitioners working with visually impaired populations to be better aware of the risks of depression and develop a wide array of preventive measures and techniques to work with individuals suffering from depression.

Abstract P194: Association of First Birth with Long-term Trajectories of Cardiovascular Health: The Coronary Artery Risk Development in Young Adults (CARDIA) Study

Background: Pregnancy is the first major physiologic stress women will experience that may exacerbate cardiovascular risk factors. Little is known about how pregnancy impacts cardiovascular health (CVH), as defined by the AHA. We examined the effects of a first birth on trajectories of CVH in a community-based sample of biracial women. Methods: CARDIA is a longitudinal study of 5,115 black and white adults aged 18-30 years at enrollment (1985-86). CVH was defined as poor, intermediate and ideal levels of 6 of 7 available AHA factors (BMI, physical activity, smoking, blood pressure, glucose, and cholesterol) assigned scores of 0, 1, and 2, respectively. A modified CVH score (CVHS) was calculated as the sum of scores from individual health factors (range 0-14; higher score=greater CVH). We employed latent-class modeling to identify distinct trajectories in CVHS over 25 years of follow up after first birth. Results: Among 1,775 baseline nulliparas (59.1% white), 888 first live births occurred. In women with ≥1 birth (Figure 1a) and with no births (Figure 1b) there were 6 distinct CVHS trajectories and most tracked over time. Trajectory patterns were similar between women with and without a birth, and select groups experienced a rapid decline in CVHS (Figure 1a: groups 1,2,5; 1b: groups 1,2,3). There is no statistically significant difference in likelihood of group membership based on number of births or exam year of first birth (1a). Conclusion: Contrary to expectation, CVHS trajectories through adulthood do not differ markedly between women with and without live births. Future analyses among subgroups at risk for longer adverse effects are being evaluated.

Population-based study to determine mortality in spina bifida: New York State Congenital Malformations Registry, 1983 to 2006.

The lifetime risk of death among individuals with spina bifida is 10-times higher compared with the general population. A population-based analysis on cause-specific mortality among individuals spina bifida is lacking. Using statewide, population-based New York Congenital Malformations Registry, we examined all births between years 1983 and 2006, and identified 1988 births with spina bifida and 10,951 births with congenital hypertrophic pyloric stenosis (CHPS). We linked registry records to birth and death files from vital records, and determined age- and cause-specific mortality for isolated and multiple spina bifida, and compared the findings with the less fatal CHPS. Mortality in spina bifida is significantly high compared with CHPS (16.9% vs. 0.96%, respectively). The probability of survival in spina bifida was lower compared with CHPS. A majority of the deaths in spina bifida occurred in infants within the first year of birth; however, an increased risk of death persisted in young adulthood for both isolated and multiple cases of spina bifida. The common causes of death in children with spina bifida were hydrocephalus, infections, cardiac anomalies, pneumonia, and pulmonary embolism; while infections, heart or kidney failure, injuries and neoplasms contributed to deaths in adults. We conclude that mortality in spina bifida is a large concern, and individuals living with the defect require improved clinical care for lethal medical complications. Primary prevention of spina bifida through mandatory folic acid fortification remains as the best strategy to reduce both disability and mortality associated with this defect across the world.

Adult-Type Intrathoracic Xanthogranuloma: Excision and Reconstruction Using a Latissimus Dorsi Muscle Flap

Adult-Type Intrathoracic Xanthogranuloma: Excision and Reconstruction Using a Latissimus Dorsi Muscle Flap

D.P.14 Mining modifier genes for skeletal muscle actin diseases

Actin and myosin are the most important muscle proteins: they generate the force of muscle contraction. Mutations of the skeletal muscle actin gene (ACTA1) cause congenital myopathies, whose commonest presentation is severe, with death within the first year of birth. However, some cases have a mild adult-onset disease suggesting other, modifier genes may be protective. In order to discover such genes, we are using The Collaborative Cross (CC). The CC is a revolutionary genetic resource, part developed at the Western Australian Institute for Medical Research. The CC is a genetic reference population of hundreds of mouse lines descended from eight very diverse founder strains allowing high resolution mapping of genes for traits of interest. Our approach is to cross Acta1 null mice, which usually die by 9days post-natal and are models of human patients with recessive ACTA1 disease, with a large panel of CC mouse strains. We will determine if any of the (CC×Acta1 null) mice are protected from the lethal myopathic phenotype, and will then use the dense genetic map (>600,000 polymorphisms) of the strains to determine the locations of modifier gene (s). In addition, we are using The CC to “mine” genetic loci associated with cardiac actin (Actc) expression in postnatal skeletal muscle. ACTC is the fetal homologue of ACTA1 in skeletal muscle, but is switched off in this tissue at birth. We previously found that transgenic ACTC expression in postnatal skeletal muscle rescues Acat1 knockout mice, suggesting ACTC could have a therapeutic role for ACTA1 diseases. The CC offers unparalleled ability to find modifier genes, as to do so in humans it would take large populations of patients with the same mutation. If we are successful in this project, we will set a precedent for applying The CC to discover disease modifier genes in any disease with a genetic basis.

Deprivation and infant feeding at birth

Aim To examine the association between the health services and increased breastfeeding rates observed in deprived areas. Methods Registered births were linked to maternity, infant and child health surveillance records held by the Information Services Division, NSS Scotland. A total of 20,338 and 6607 singleton births to first time mothers between 2003 and 2009 were linked in the most and least deprived areas (Scottish Index of Multiple Deprivation – SIMD 2006) respectively. Infant feeding was assessed at birth. Multiple births and infants who died within the first year of birth were excluded from the analysis. Descriptive and multivariate analysis (logistic regression – forwards and manual) was conducted using SPSS vs 17 and STATA vs 11. Results There was an increase in any breastfeeding rates at birth (mixed and exclusive) observed in the most deprived areas from 41% in 2001 to 49% in 2009 compared to the least deprived areas which remained relatively stable (figure 1). Mixed feeding formed an important component of any breastfeeding in the most deprived areas (figures 2 and 3). However, the increasing trends were not evident when confounding factors were accounted for (p A range of demographic, socio-cultural, maternal and infant health characteristics and features of the health system independently predicted the types and duration of any breastfeeding in the most deprived areas. In particular, older maternal age > 25 years, mother of non-British birth, maternal and paternal socio-economic status and maternal health/health behaviour influenced the observed trends in the deprived areas. A ‘hospital effect’ was also observed (table 1). Conclusion The linked data set is an invaluable resource for exploring trends in deprived areas and highlights factors that promote breastfeeding in these areas. Increased breastfeeding rates observed in deprived areas can in part be attributed to changes in the composition of the population e.g. more mothers of non-British birth. In addition, a higher prevalence of mixed feeding over time reflects a shift in infant feeding patterns (and a possible process of acculturation). A number of factors influence the likelihood to provide any breast milk at birth underlining the importance of multi-factorial interventions to promote breastfeeding in deprived areas.

Between The Questionnaire And Cotinine Level For Studying Exposure To Tobacco Smoke Among Allergy And Healthy Children

RATIONALE: Several International Study of Asthma and Allergies in Childhood (ISAAC) studies have showed that environmental tobacco smoke (ETS) was strong risk factor for allergic diseases. The underreporting of ETS exposure by parents of study children may depend on the instrument used. We evaluated exposure to ETS by questionnaires and urinary cotinine level to validate the questionnaire. METHODS: The study population was composed of 340 children ages 4 to 6 years. Exposure to ETS was evaluated both by ISAAC questionnaires and level of urine cotinine by an enzyme immunoassay. The questionnaires were three categories, during pregnancy, first year of birth, and previous 12 months. RESULTS: The urinary cotinine concentrations were higher in children living with smoking parents (22.1± 4.3 ng/mg) compared with children not exposed to parental smoke (5.6±3.2 ng/mg; p = 0.01). However, it did not differ between the questionnaires. CONCLUSIONS: These results show that our questionnaire is not discriminating enough to distinguish between the onsets of exposure, but reveals gradients of higher exposure. In further, evaluation with an objective method of the exposure to second-hand smoke.

Differential infant and child mortality in three Dutch regions, 1812–19091

New micro‐level data have recently become available for three provinces of The Netherlands for the period 1812–1912, which allow the study of the evolution of socio‐economic differentials in infant and childhood mortality. The authors found significant differences in the levels of infant mortality by social group between the three provinces, and a wide variety in the pattern of social inequality. This showed the importance of the regional environment for the level of infant mortality in the nineteenth century. Contrary to expectations, strong social differences were also observed in neonatal mortality. Being born in an urban environment did not have a strong effect on survival during the first year of birth.

Determinants of child mortality in LDCs: Empirical findings from demographic and health surveys

Empirical studies on child mortality at the disaggregated level-by social-economic group or geographic location—are more informative for designing health polices. Using Demographic and Health Survey data from over 60 low-income countries, this study (1) presents global patterns of the level and inequality in child mortality and (2) investigates the determinants of child mortality, both at the national level and separately for urban and rural areas. The global patterns of health outcomes reveal two interesting observations. First, as child mortality declines, the gap in mortality between the poor and the better-off widens. Second, while child mortality in rural areas is substantially higher than in urban areas, the reduction in child mortality is much slower in rural areas where the poor are concentrated. This suggests that health interventions implemented in the past decade may not have been as effective as intended in reaching the poor. The analysis on mortality determination shows that at the national level access to electricity, incomes, vaccination in the first year of birth, and public health expenditure significantly reduce child mortality. The electricity effect is large and independent of the income effect. While in urban areas, access to electricity is the only significant mortality determinant, in rural areas, vaccination in the first year of birth is the only significant factor.

Impact of low birthweight on subsequent fertility: population-based register study.

Adverse birth outcomes may influence a family's wish for additional children. We investigated the influence of low birthweight in live births on subsequent fertility, and estimated secular trends of such an effect in a population-based cohort study of births arranged in consecutive sibship records in the Medical Birth Registry of Norway. We included births of order one to seven to all 587 785 mothers in Norway who had a first singleton birth in 1967-91. Associations between birthweight in 1 158 072 surviving index births of order one to six, 1967-91, and subsequent fertility (probability of another birth), 1967-97, were estimated as fertility ratios in Cox regression analysis. Giving birth to a live infant weighing < 3000 g had a negative effect on subsequent fertility, increasingly strong for decreasing birthweight. Low birthweight (<2500 g) was associated with a fertility ratio of 0.88 [95% confidence interval 0.87, 0.89]. This negative impact was stronger if the mother had also given birth to surviving children of low birthweight previously, particularly if combined with caesarean section in the most recent birth. The negative fertility effect of low birthweight grew slightly stronger between 1967 and approximately 1980, according to year of first birth. This trend paralleled reduced population fertility in the same period. The moderate negative impact of giving birth to a live infant of low birthweight on subsequent fertility could result from the combination of reduced wish for additional children and biological subfertility.

Antiretrovirals for reducing the risk of mother-to-child transmission of HIV infection.

At the end of 2000 it was estimated that over 36 million people were living with the human immunodeficiency virus (HIV). This includes 1.4 million children less than 15 years of age. This is one of several reviews assessing the available evidence for preventing mother-to-child transmission of HIV infection. The other reviews will address other interventions, including Caesarean section, breast feeding, vaginal lavage and vitamin A supplementation. To assess which antiretroviral therapies may be effective in decreasing the risk of mother-to-child transmission of HIV infection as well as their effect on neonatal and maternal mortality and morbidity. We searched the Cochrane Pregnancy and Childbirth Group trials register and the Cochrane Controlled Trials Register. We also searched conference abstracts from the International AIDS Conferences and Conference on Retroviruses and Opportunistic Infections. Randomised trials comparing any antiretroviral therapy aimed at decreasing the risk of mother-to-child transmission of HIV infection with placebo or no treatment, or any two or more antiretroviral therapies or regimens aimed at decreasing the risk of mother-to-child transmission of HIV infection. Two reviewers independently extracted data and assessed trial quality. Zidovudine monotherapy Any zidovudine regimen versus placebo significantly reduces the risk of mother-to-child transmission (Peto odds ratio (OR) 0.46, 95% confidence interval (CI) 0.35 to 0.60). Zidovudine also appears to decrease the risk of infant death within the first year of birth (OR 0.57, 95% CI 0.38 to 0.85) and the risk of maternal death (OR 0.32, 95% CI 0.16 to 0.66). There is no evidence that zidovudine influences the incidence of premature delivery (OR 0.86, 95% CI 0.57 to 1.29) or low birth weight (OR 0.74, 95% CI 0.53 to 1.04). The risk of transmission using a 'short-short' course of zidovudine (from 35 weeks in pregnancy for the mother and for the baby until 3 days old) was higher than the risk using a 'long-long' course (from 28 weeks in pregnancy for the mother and for the baby until 6 weeks old), (OR 2.55, 95% CI 1.26 to 5.18). However, the effectiveness of the 'long-short' course (from 28 weeks in pregnancy for the mother and for the baby until 3 days old) and the 'short-long' course (from 35 weeks in pregnancy for the mother and for the baby until 6 weeks old) did not differ from that of the 'long-long' course. Nevirapine One large randomised controlled trial demonstrates that nevirapine given to mothers as a single dose at the onset of labour and to babies as a single dose within 72 hours of birth is more effective than an intrapartum and post-partum regimen of zidovudine (OR 0.51, 95% CI 0.33 to 0.79). When nevirapine is given to mothers already receiving standard antiretroviral therapy, however, there appears to be no additional advantage (OR 1.10, 95% CI 0.42 to 2.86). Combination Therapy Preliminary findings of the effect of combination therapy using zidovudine and lamivudine (3TC) suggest a decrease in the risk of transmission when the combination is given during the antenatal and intrapartum period or during the intrapartum and postpartum period compared with placebo. There is no evidence that intrapartum zidovudine and lamivudine alone are sufficient to decrease the risk of transmission compared with placebo. Implications for practice The randomised trials included in this review provide evidence that short course zidovudine and single-dose nevirapine are effective therapies for reducing mother-to-child transmission of HIV. The challenge for low and middle income countries will be to institute this therapy in practice. In industrialised countries practice has already moved on from the current evidence and combination antiretroviral therapy aimed primarily at preventing disease progression in the mother is the standard of care. Implications for research The potential value of nevirapine used for longer durations in breastfeeding populations should be considered as it may further reduce the risk of mother-to-child transmission, particularly if combined with early weaning. On-going evaluation of combination antiretroviral therapy is essential and will have an immediate benefit for countries with the resources to adopt such treatment. The search for effective, affordable, safe and acceptable alternatives to antiretroviral therapy for reducing mother-to-child transmission in resource poor countries should remain on the research agenda.

Does the increased risk of preterm delivery in teenagers persist in pregnancies after the teenage period?

To study the associations between low maternal age at first birth and the risks of very and moderately preterm birth, in first birth and in second successive birth in adulthood. Population-based cohort study. Sweden. POPULATION Women aged less than 25 years at first birth (n = 275,933), having two successive live single births from 1973 through 1993. Odds ratios with 95 percent confidence intervals were calculated to estimate the effect of low maternal age at first birth. Analyses of first births were adjusted for year of first birth and maternal education and in second births also for previous pregnancy outcomes and interpregnancy interval. Very preterm birth (less than 33 completed weeks) and moderately preterm birth (33-36 completed weeks). Compared with women aged 20 to 24 years at first birth, mothers aged 13 to 15 years were at increased risk of very preterm birth (odds ratio = 4.8). The corresponding risks among women aged 16 to 17 years at first birth were doubled (odds ratio = 2.3). The influence of maternal age on risks of moderately preterm birth was similar, although the age-related risks were lower. At second birth, risks of preterm birth were reduced in all age groups. However, mothers who were 17 years or less at first birth, faced, compared with mothers aged 20-24 years, significantly larger reduction in risks of very and moderately preterm birth. Our results suggest that there may be a biological effect of very young maternal age, affecting foremost very preterm birth.

Does the increased risk of preterm delivery in teenagers persist in pregnancies after the teenage period?

Objective To study the associations between low maternal age at first birth and the risks of very and moderately preterm birth, in first birth and in second successive birth in adulthood. Design Population-based cohort study. Setting Sweden. Population Women aged less than 25 years at first birth ( n=275,933), having two successive live single births from 1973 through 1993. Methods Odds ratios with 95 percent confidence intervals were calculated to estimate the effect of low maternal age at first birth. Analyses of first births were adjusted for year of first birth and maternal education and in second births also for previous pregnancy outcomes and interpregnancy interval. Main outcome measures Very preterm birth (less than 33 completed weeks) and moderately preterm birth (33-36 completed weeks). Results Compared with women aged 20 to 24 years at first birth, mothers aged 13 to 15 years were at increased risk of very preterm birth (odds ratio=4.8). The corresponding risks among women aged 16 to 17 years at first birth were doubled (odds ratio=2.3). The influence of maternal age on risks of moderately preterm birth was similar, although the age-related risks were lower. At second birth, risks of preterm birth were reduced in all age groups. However, mothers who were 17 years or less at first birth, faced, compared with mothers aged 20-24 years, significantly larger reduction in risks of very and moderately preterm birth. Conclusions Our results suggest that there may be a biological effect of very young maternal age, affecting foremost very preterm birth.

Incidence of breast cancer in Norwegian female radio and telegraph operators

Exposure to electromagnetic fields may cause breast cancer in women if it increases susceptibility to sex-hormone-related cancer by diminishing the pineal gland's production of melatonin. We have studied breast cancer incidence in female radio and telegraph operators with potential exposure to light at night, radio frequency (405 kHz-25 MHz), and, to some extent, extremely low frequency fields (50 Hz). We linked the Norwegian Telecom cohort of female radio and telegraph operators working at sea to the Cancer Registry of Norway to study incident cases of breast cancer. The cohort consisted of 2,619 women who were certified to work as radio and telegraph operators between 1920 and 1980. Cancer incidence was analyzed on the basis of the standardized incidence ratio (SIR), with the Norwegian female population as the comparison group. The incidence of all cancers was close to unity (SIR = 1.2). An excess risk was seen for breast cancer (SIR = 1.5). Analysis of a nested case-control study within the cohort showed an association between breast cancer in women aged 50+ years and shift work. In a model with adjustment for age, calendar year, and year of first birth, the rate ratio for breast cancer associated with being a radio and telegraph operator--in comparison with all Norwegian women born 1935 or later--analyzed with Poisson regression, was 1.5 after adjustment for fertility factors. These results support a possible association between work as a radio and telegraph operator and breast cancer. Future epidemiologic studies on breast cancer in women aged 50 and over, should address possible disturbances of chronobiological parameters by environmental factors.