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ABSTRACT: An association between preterm birth and an increased risk for childhood asthma has been demonstrated but the importance of intrauterine growth retardation on asthma risk is unclear.Using data from Swedish health registers, infant characteristics and childhood asthma were studied. Analyses were made using Mantel-Haenszel methodology with adjustment for year of birth, maternal age, parity, smoking in early pregnancy, and maternal body mass index. Preterm birth, birth weight and birth weight for gestational week were analysed and childhood asthma was evaluated from prescriptions of anti-asthmatic drugs. Neonatal respiratory problems and treatment for them were studied as mediating factors.Both short gestational duration and intrauterine growth retardation appeared as risk factors and seemed to act separately. The largest effect was seen from short gestational duration. Use of mechanical ventilation in the newborn period and bronchopulmonary dysplasia were strong risk factors. A moderately increased risk was also seen in infants born large for gestational age.We conclude that preterm birth is a stronger risk factor for childhood asthma than intrauterine growth disturbances, but the latter also affects the risk, also in term infants.
European Respiratory Journal 06/2012; · 5.89 Impact Factor
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ABSTRACT: Relatively few studies published to date have investigated IVF and cancer risk. In this study we compared the occurrence of cancer in women who gave birth after IVF with all other women who gave birth in the study period.
All women who were treated with IVF and gave birth during the years 1982-2006 in Sweden were identified from all IVF clinics, and the occurrence of cancer in these women was identified by linkage with the nationwide Swedish cancer register. Comparison was made with Mantel-Haenszel odds ratios (ORs), adjusting for year of delivery and maternal age, parity and smoking. Cancer before IVF was only studied in first parity women. Specific cancer forms were also studied.
Among 24058 women who had been treated with IVF, 1279 appeared in the cancer register. The total number of women studied in the population was 1 394 061, and 95 775 of these were registered in the cancer register. The risk for cancer before IVF was increased [OR 1.37, 95% confidence interval (CI) 1.27-1.48] and was especially high for ovarian cancer (3.93). The risk for cancer after IVF was significantly lower (OR 0.74, 95% CI 0.67-0.82), mainly due to a lower than expected risk for breast and cervical cancer. The risk for ovarian cancer was increased but lower than the risk before IVF (2.13).
Cancer or cancer treatment may increase the risk for infertility leading to IVF. After IVF, in most cases with treatment with fertility hormones, a significantly low cancer risk was found. Ovarian cancer showed an increased risk, although lower than before IVF. One possible reason is ovarian pathology causing both infertility and an increased cancer risk.
Human Reproduction 11/2010; 26(1):253-8. · 4.47 Impact Factor
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ABSTRACT: Marked changes have occurred in in vitro fertilization (IVF) methodology during the past 25 years but also in characteristics of couples undergoing treatment.
This study was based on 27 386 women undergoing IVF treatment from 1982 to 2006 and giving birth to 31 850 infants. Outcomes of deliveries were studied using Swedish health registers. Comparisons were made with all deliveries in the population (n = 2 603 601). Adjusted odds ratios were calculated when important changes in background rates had occurred.
There was a substantial increase in the use of intracytoplasmatic sperm injection (ICSI) and the transfer of cryopreserved embryos. Among all ICSI cases, the proportion using epididymal or testicular sperm varied between 5 and 10%. Maternal characteristics changed during the observation period but the median age remained relatively constant in spite of the increasing maternal age in the population. There was a decline in the rate of some maternal pregnancy diagnoses (notably pre-eclampsia, premature rupture of membranes) and some neonatal diagnoses (notably preterm births, low birthweight, cerebral hemorrhage, respiratory diagnoses, use of continuous positive airway pressure and mechanical ventilation, sepsis/pneumonia). Up till 1992, the twinning rate increased to a maximum of about 30% and then declined to 5% towards the end of the period whereas higher order multiples nearly disappeared. The total rate of infants with congenital malformations changed only little.
The decrease in unwanted outcomes can, to a large extent, be explained by the reduced rate of multiple births but was seen also among singletons. Other explanations can be sought in changes in the characteristics of patients undergoing IVF.
Human Reproduction 02/2010; 25(4):1026-34. · 4.47 Impact Factor
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ABSTRACT: To compare neonatal outcome among twins conceived after in vitro fertilisation (IVF) with that of spontaneously conceived twins.
Comparison of different-sex (dizygotic) twins born after IVF with non-IVF dizygotic twins.
National health registers in Sweden.
All births in Sweden during the period 1982-2007.
We studied gestational duration, lowest birthweight and birthweight difference in the twin pair, presence of one or two twins with a respiratory complication, and with jaundice in one or both twins. Risk estimates were calculated as odds ratios with adjustments for year of birth, maternal age, parity and smoking in pregnancy.
Gestational duration, birth weight, respiratory complications, jaundice.
We studied 1545 pairs of dizygotic twins born after IVF, and 8675 pairs of dizygotic twins where IVF was not known to have occurred. The risk for preterm delivery before 32 weeks of gestation was significantly increased among dizygotic twin pairs born after IVF compared with non-IVF dizygotic twin pairs. No significant difference in low birthweight or birthweight difference within twin pairs was seen. There was an increased occurrence of twin pairs with respiratory problems or jaundice, but only the latter diagnosis occurred in a statistically significant excess.
The study confirms recent findings that IVF is associated with an increased risk for some neonatal complications, not only among singletons but also among twins.
BJOG An International Journal of Obstetrics & Gynaecology 02/2010; 117(6):676-82. · 3.41 Impact Factor
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ABSTRACT: To investigate maternal and neonatal factors in Down syndrome (DS) at birth, the impact of a congenital heart defect (CHD) on these factors and changes over time.
Medical data of children with DS born in northern Sweden in the periods 1973-1980 (n = 219) and 1995-1998 (n = 88) obtained from the Swedish Medical Birth Register were compared. A comparison with the general population on a group level was also made.
The main finding was a reduction in infant mortality in DS, from 14.2% to 2.3% in 1995-1998 (p < 0.001), but this was still significantly higher than in the general population. The rate of Caesarean sections increased over time (from 14.5% to 27.3%, p < 0.05) even after adjustment for increased maternal age. No change over time was detected in the following rates: premature birth (gestational age < or = 36) (25%); asphyxia (5-min Apgar score < or = 6) (8%); low birthweight (< 2500 g) (14%); or small for gestational age (SGA) (14%); all rates were significantly higher than those of the general population. A CHD did not seem to influence the rates of these factors in a logistic regression model.
Infant mortality decreased substantially over time in the DS group, whereas there was no reduction in the rate of asphyxia, SGA, low birthweight or prematurity. The presence of a CHD did not influence any of the neonatal factors studied.
Acta Paediatrica 02/2004; 93(1):106-12. · 2.07 Impact Factor
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ABSTRACT: To study the neonatal outcome in pregnancies after ovarian stimulation, not including in vitro fertilization. The outcomes studied were multiple birth, preterm birth, and low birth weight among singletons, congenital malformations, and infant death.
We identified 4029 women who delivered between 1995-1999 after ovarian stimulation alone and compared them with 438,582 women who neither had ovarian stimulation nor in vitro fertilization. We controlled for the confounding effect of year of birth, maternal age, parity, and length of subfertility before the pregnancy.
The twinning rate was 5.9% in the study group and 1.2% in the control group. The triplet rate was 0.5% in the study group and 0.02% in the control group. A nearly doubling of the rate of monozygotic twinning was indicated in the study group compared with the control group. There was an excess of singleton preterm births and low birth weight infants in the study group, but this was mainly explainable by confounding of maternal age, parity, and subfertility. The rates of congenital malformations and perinatal deaths were increased, also mainly explainable by maternal characteristics. No increase in specific types of congenital malformations was seen.
As the deviations in neonatal outcome after ovarian stimulation alone were reduced or disappeared when the confounding of maternal age, parity, and subfertility was taken into consideration, there is probably little direct effect of the stimulation procedure as such.
Obstetrics and Gynecology 10/2002; 100(3):414-9. · 4.73 Impact Factor
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ABSTRACT: Infants born after IVF are often twins, and singleton IVF babies have an increased risk for preterm birth. Both conditions are likely to increase morbidity. We examined the frequency and duration of hospitalization required by babies born after IVF, and compared this information with all infants born in Sweden during the same time period.
We used a nationwide registration of IVF pregnancies from 1984 to 1997 and a nationwide register of all in-patient care up to the end of 1998. We identified 9056 live born infants after IVF treatment and compared them with 1 417 166 non-IVF live born infants.
The highest odds ratio (OR approximately 3) was seen for neonatal hospitalization, but an increased OR (1.2-1.3) was noted for children up to 6 years of age. The OR for being hospitalized after IVF was 1.8, but when the analysis was restricted to term infants it was 1.3 and this excess was then explainable by maternal subfertility. Statistically significant increased ORs were seen for hospitalization for cerebral palsy (1.7), epilepsy (1.5), congenital malformation (1.8) or tumour (1.6), but also for asthma (1.4) or any infection (1.4). When information from the Swedish Cancer Registry was used, no excess risk for childhood cancer was found. The average number of days spent in hospital by IVF and non-IVF children was 9.5 and 3.6 respectively.
The increased hospitalization of IVF children is, to a large extent, due to the increased incidence of multiple births. Therefore, the increased costs associated with this may be reduced by the use of single embryo transfers, with the savings in health care costs being offset against the increased number of embryo transfer cycles required to maintain the pregnancy rate.
Human Reproduction 05/2002; 17(4):929-32. · 4.47 Impact Factor
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Lakartidningen 04/1999; 96(13):1560-2, 1565-7.
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ABSTRACT: A prospective national investigation comprising 633 extremely low birthweight (ELBW) infants born alive in the 2-y period 1990-1992 with a birthweight of < or = 1000 g and gestational age of > or = 23 completed weeks was conducted regarding neurosensory outcome and growth. Three-hundred and sixty-two (98%) surviving ELBW infants were assessed at a median age of 36 months, using a specially designed protocol. At follow-up, mean height, weight and head circumference in both boys and girls were significantly lower than the reference values. The incidence of cerebral palsy was 7% among all children and 14%, 10% and 3% in children born at 23-24, 25-26 and > or = 27 gestational weeks, respectively. At least one obvious handicap was present in 14%, 9% and 3% of these three groups of children, respectively. After adjustment for gestational age, a significantly increased risk of handicap was found in children with intraventricular haemorrhage grade > or = 3 and/or periventricular leucomalacia and in children with retinopathy of prematurity stage > or = 3. The results show that more than 90% of ELBW children born at > or = 25 completed gestational weeks were without neurosensory handicap at 36 months of corrected age. In infants born at 23-24 weeks of gestation, both survival and long-term outcome were less favourable.
Acta Paediatrica 11/1998; 87(10):1055-60. · 2.07 Impact Factor
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ABSTRACT: In a previous article, a high infant mortality was reported in the 1980s in Norway compared with Sweden. The aim of the present study was to assess secular trends in this difference, and to clarify whether the difference was confined to particular causes of death. Mortality rates, ratios of mortality rates and numbers of excess deaths were calculated on the basis of birth records comprising all livebirths in Norway and Sweden during the two periods 1975-79 and 1985-88. From the first to the second period, the infant mortality ratio for Norway to Sweden increased from 1.22 to 1.45 for single births, and from 1.23 to 1.54 for twin births. Increasing mortality ratios were observed for all ages at death. These were lowest in the early neonatal period (1.09 and 1.20 respectively) and highest in the postneonatal period (1.53 and 1.78 respectively). Within each cause of death category, the mortality rate in Norway was equal to or higher than the rate in Sweden. The highest mortality rate ratios were observed for sudden infant death syndrome (SIDS), 2.44 and 2.46 respectively, for the two time periods. SIDS was also the single cause of death that gave the largest contribution to the Norwegian excess mortality (45% and 53% overall, 65% and 78% for postneonatal deaths, and 65% and 79% for birthweights above 2500 g). In the second period, the excess SIDS mortality in Norway pertained mainly to infants of young mothers, infants of birth order two or more and twin births. An adverse trend for infants of young mothers in Norway was also observed in non-SIDS deaths. This suggests that in Norway, preventive health care should be improved, particularly for young mothers and their infants.
Paediatric and Perinatal Epidemiology 05/1997; 11(2):214-27. · 2.31 Impact Factor
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ABSTRACT: In a 2-year (1990-92) prospective national investigation, comprising all stillborn and live-born ELBW infants with a birthweight of ≤1000 g born at 23 completed weeks of gestation or more, we examined the incidence, neonatal mortality, major morbidity and infant survival in relation to level of care and place of residence. A total of 633 ELBW infants were live-born, i.e. 0.26% of all live-born infants, and 298 were stillborn. The average neonatal mortality was 37% and 91% at 23 weeks, 70% at 24 weeks, and 40% at 25 weeks of gestation. Of neonatal survivors, 8% had intraventricular haemorrhage grade 3,10% retinopathy of prematurity of stage ≥3, 2% necrotizing enterocolitis, and 28% were oxygen-dependent at a time corresponding to 36 weeks of gestation. In all, 77% were treated with mechanical ventilation, whereas 19% survived without, almost all of them being CPAP treated. Infant mortality among infants born at level III (tertiary centres) was 30%, at level Ha (with full perinatal service) 46% and at level IIb (with basic neonatal service) 55 %. Only 1 % was born at hospital level I. Regarding the relation to place of residence, the mortality rates among infants residing in the areas served by levels III, IIa and lib hospitals were 36%, 45% and 41%, respectively. The referral system thus functioned well, but can be improved, and increased perinatal referral, at borderline perinatal viability, might provide a better quality of care and a better chance of survival.
Acta Paediatrica 04/1997; 86(5):503 - 511. · 2.07 Impact Factor
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ABSTRACT: Several risk factors for sudden infant death syndrome (SIDS) have been consistently reported, while results regarding seasonality and age at death of SIDS victims are conflicting. In the present population-based cohort study, single births in Sweden from 1983 through 1990 were used to estimate the relative and absolute risks for SIDS associated with season at death, age at death, and maternal smoking. In the winter period, 283 SIDS deaths occurred, while only 98 infants died during summer (winter/summer ratio = 2.9). Taking person-time at risk into account and restricting the analysis to infants aged 7-180 days, the authors determined the relative risk for SIDS to be 3.5 times higher in winter than in summer. When comparing incidence rate differences, they found a more noticeable seasonal variation for early SIDS (7-90 days at death) than for late SIDS (91-180 days at death). For early SIDS, the incidence rate was 0.6 cases per 100,000 person-days higher among smokers than among nonsmokers; for late SIDS, the corresponding difference was 0.3. The effect of smoking on SIDS was not associated with seasonality. Since exposure to passive smoking is likely to vary by season, the results suggest that the effect of smoking on SIDS is prenatal rather than the result of passive smoking after birth.
American Journal of Epidemiology 10/1995; 142(6):619-24. · 5.22 Impact Factor
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ABSTRACT: Experimental studies show that some compounds in tobacco smoke are transplacental carcinogens, but epidemiological data on maternal smoking and childhood cancer are inconclusive. Using the national Swedish Medical Birth and Cancer Registries, the incidence of cancer was followed through 1987 in a cohort of 497,051 children born 1982-1987 for whom information was available on maternal smoking at 2-3 months of pregnancy. A total of 327 cancers appeared including 198 solid tumours and 129 cancers of the lymphatic and haematopoietic system. The overall relative risk for cancer in children with mothers reporting smoking during pregnancy was 0.99 (95% confidence interval (CI): 0.78-1.27). Corresponding risks for solid tumours and cancers of the lymphatic/haematopoietic system were 0.96 (0.70-1.32) and 1.04 (0.71-1.52), respectively. There was no consistent increase in risk for cancer of different sites or in relation to number of cigarettes smoked per day.
International Journal of Epidemiology 03/1992; 21(1):1-5. · 6.41 Impact Factor
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ABSTRACT: Since 1982, prospective information on smoking during early pregnancy is reported to the Swedish Medical Birth Registry for nearly all (93%) women who give birth. The present paper studies the validity of this information: effects on birthweight and perinatal mortality are very similar to those described previously in the literature. For each parity class, smoking decreases in inverse proportion to increasing maternal age; for each maternal age class, smoking increases with parity. A slight reduction in smoking rate is observed between 1983 and 1987, most pronounced for young women. There are marked geographic and social differences in the rate of smoking during pregnancy. This dataset can be used in the future to monitor the prevalence of smoking, and to study various factors associated with smoking and the impact of countermeasures taken against smoking during pregnancy. It can also be used to study possible associations between maternal smoking and rare events like congenital malformations and child cancer.
Acta Obstetricia Et Gynecologica Scandinavica 02/1991; 70(2):111-7. · 1.77 Impact Factor
