Karin Källén

One-year survival of extremely preterm infants after active perinatal care in sweden

CONTEXT Up-to-date information on infant survival after extremely preterm birth is needed for assessing perinatal care services, clinical guidelines, and parental counseling. OBJECTIVE To determine the 1-year survival in all infants born before 27 gestational weeks in Sweden during 2004-2007. DESIGN, SETTING, AND PATIENTS Population-based prospective observational study of extremely preterm infants (707 live-born and 304 stillbirths) born to 887 mothers in 904 deliveries (102 multiple births) in all obstetric and neonatal units in Sweden from April 1, 2004, to March 31, 2007. MAIN OUTCOME MEASURES Infant survival to 365 days and survival without major neonatal morbidity (intraventricular hemorrhage grade >2, retinopathy of prematurity stage >2, periventricular leukomalacia, necrotizing enterocolitis, severe bronchopulmonary dysplasia). Associations between perinatal interventions and survival. RESULTS The incidence of extreme prematurity was 3.3 per 1000 infants. Overall perinatal mortality was 45% (from 93% at 22 weeks to 24% at 26 weeks), with 30% stillbirths, including 6.5% intrapartum deaths. Of live-born infants, 91% were admitted to neonatal intensive care and 70% survived to 1 year of age (95% confidence interval [CI], 67%-73%). The Kaplan-Meier survival estimates for 22, 23, 24, 25, and 26 weeks were 9.8% (95% CI, 4%-23%), 53% (95% CI, 44%-63%), 67% (95% CI, 59%-75%), 82% (95% CI, 76%-87%), and 85% (95% CI, 81%-90%), respectively. Lower risk of infant death was associated with tocolytic treatment (adjusted for gestational age odds ratio [OR], 0.43; 95% CI, 0.36-0.52), antenatal corticosteroids (OR, 0.44; 95% CI, 0.24-0.81), surfactant treatment within 2 hours after birth (OR, 0.47; 95% CI, 0.32-0.71), and birth at a level III hospital (OR, 0.49; 95% CI, 0.32-0.75). Among 1-year survivors, 45% had no major neonatal morbidity. CONCLUSION During 2004 to 2007, 1-year survival of infants born alive at 22 to 26 weeks of gestation in Sweden was 70% and ranged from 9.8% at 22 weeks to 85% at 26 weeks.

Incidence of and risk factors for neonatal morbidity after active perinatal care : extremely preterm infants study in Sweden (EXPRESS)

Aims:  The aim of this study was to determine the incidence of neonatal morbidity in extremely preterm infants and to identify associated risk factors.

Caesarean section increases the risk of hospital care in childhood for asthma and gastroenteritis.

Objective To investigate if caesarean section (CS) increases the risk for childhood asthma and gastroenteritis with reference made to children born with vaginal delivery (VD).

Preterm birth in Sweden 1973-2001: Rate, subgroups, and effect of changing patterns in multiple births, maternal age, and smoking

Background.  The objectives of this report are to evaluate changes in the preterm birth rate in Sweden 1973–2001. Furthermore, describe the proportion of spontaneous and indicated preterm births and assess risk factors for the subgroups of preterm birth during the period from 1991 to 2001.

Obstetric outcome in singletons after in vitro fertilization with cryopreserved/thawed embryos

BACKGROUND There is increasing use of cryopreservation in IVF. This study compared singletons born after cryopreservation with singletons born after fresh IVF cycles and singletons born to women in the general population. METHODS Data were collected for Swedish IVF treatments during the years 2002-2006. All singletons from single embryo transfer (SET) and double embryo transfer (DET) after cryopreserved (n = 2348) and fresh cycles (n = 8944) were included and cross-linked with the Swedish Medical Birth Registry and compared with all singletons born after spontaneous conception (n = 571 914). Main outcomes were preterm and very preterm birth and low and very low birthweight (VLBW). Other outcomes were small for gestational age, large for gestational age (LGA), perinatal mortality and maternal outcomes. RESULTS Singletons from cryopreserved SET/DET or cryopreserved SET had increased rates of extreme preterm birth compared with singletons from the general population. A lower rate of LBW was found for cryopreserved SET/DET singletons compared with singletons from fresh cycles; however, a higher rate of perinatal mortality was detected. The rates of LGA and macrosomia were increased for cryopreserved SET/DET singletons when compared with those from fresh cycles and the general population. For maternal outcomes, a higher rate of pre-eclampsia was noted for pregnancies from cryopreserved cycles compared with those from fresh cycles or the general population, but the rate of placenta praevia was lower in pregnancies from cryopreserved cycles compared with those from fresh cycles. CONCLUSIONS The obstetric outcome of singletons after cryopreservation was slightly poorer when compared with the general population. In comparison with fresh cycles, the outcome varied. The finding of an increased rate of LGA after cryopreservation requires further study.

Stillbirths and rate of neonatal deaths in 76,761 postterm pregnancies in Sweden, 1982-1991: a register study

Objective. To study stillbirths and neonatal mortality in the postterm period.Stillbirths and rate of neonatal deaths in 76,761 postterm pregnancies in Sweden, 1982-1991

Paper 6: EUROCAT member registries: organization and activities

BACKGROUND EUROCAT is a network of population-based congenital anomaly registries providing standardized epidemiologic information on congenital anomalies in Europe. There are three types of EUROCAT membership: full, associate, or affiliate. Full member registries send individual records of all congenital anomalies covered by their region. Associate members transmit aggregate case counts for each EUROCAT anomaly subgroup by year and by type of birth. This article describes the organization and activities of each of the current 29 full member and 6 associate member registries of EUROCAT. METHODS Each registry description provides information on the history and funding of the registry, population coverage including any changes in coverage over time, sources for ascertaining cases of congenital anomalies, and upper age limit for registering cases of congenital anomalies. It also details the legal requirements relating to termination of pregnancy for fetal anomalies, the definition of stillbirths and fetal deaths, and the prenatal screening policy within the registry. Information on availability of exposure information and denominators is provided. The registry description describes how each registry conforms to the laws and guidelines regarding ethics, consent, and confidentiality issues within their own jurisdiction. Finally, information on electronic and web-based data capture, recent registry activities, and publications relating to congenital anomalies, along with the contact details of the registry leader, are provided. CONCLUSIONS The registry description gives a detailed account of the organizational and operational aspects of each registry and is an invaluable resource that aids interpretation and evaluation of registry prevalence data.

Maternal smoking and congenital heart defects.

The Swedish Child Cardiology Registry (CCR) and the Swedish Medical Birth Registry (MBR) were used to investigate a possible association between maternal smoking during pregnancy and congenital heart defects. Among 1,413,811 infants born in 1983–1996 with known smoking exposure in early pregnancy, 3384 infants with congenital heart defects were selected (458 term infants with persistent ductus arteriosus (PDA) identified from MBR or CCR, and 2926 infants with other heart defects, identified from CCR). After controlling for year of birth, maternal age, parity, and educational level, a weak, statistically significant association between all heart defects and maternal smoking was found (odds ratio (OR): 1.09; 95% confidence interval (CI): 1.01–1.19). When infants with isolated PDA were removed from the case group the significance disappeared (OR: 1.07; 95% CI: 0.98–1.17). For truncus abnormalities (OR: 1.23; 95% CI: 1.02–1.49), atrial septal defects (OR: 1.63; 95% CI: 1.04–2.57), and PDA (OR: 1.30; 95% CI: 1.05–1.62), a rather strong effect of maternal smoking was indicated. The increased OR for PDA remained when gestational duration and intrauterine growth was also controlled for. Further research based on independent data sets is needed to conclude whether the risk estimates for maternal smoking are true and truly differ between the groups. The classification system used (with 24 classes) is described in enough detail to permit a repetition of the study.

Maternal smoking and craniosynostosis.

To investigate a possible association between maternal smoking during pregnancy and craniosynostosis (premature closure of one or more of the cranial sutures), a study was conducted using Swedish health registries. Infants with craniosynostosis (n = 304) without a known chromosome anomaly were selected among 1,413,811 infants born between 1983-1996 with known smoking exposure in early pregnancy. A statistically significant association between maternal smoking and craniosynostosis was found (adjusted odds ratio (OR), 1.45; 95% confidence interval (CI), 1.13-1.87), but this association was only valid for isolated defects (OR, 1.67; 95% CI, 1.27-2.19). For associated craniosynostosis (malformation syndromes included), a negative (nonsignificant) association with maternal smoking was indicated instead. For isolated craniosynostosis (all types), a dose-dependent effect of maternal smoking was indicated (OR and 95% CI for smoking <10 cigarettes/day, 1.45 (1.04-2.02); OR and 95% CI for smoking >/=10 cigarettes/day, 2.12 (1.50-2.99)), but was not statistically significant. Among the different types of craniosynostosis, premature closure of the sagittal suture showed the strongest association with maternal smoking (OR, 1.48; 95% CI, 1. 02-2.14), whereas for coronal suture defects, no association with maternal smoking could be detected (OR, 1.02; 95% CI, 0.47-2.21). As no obvious confounders were detected, the present study supports an earlier report of an association between maternal smoking during pregnancy and at least some types of craniosynostosis.

Risk factors for autism and Asperger syndrome Perinatal factors and migration

Using the Swedish Medical Birth Registry (MBR), obstetrical and demographic information was retrieved for 250 children with autism or Asperger syndrome who were born in Malmoe, Sweden, and enrolled at the local Child and Youth Habilitation Center. The reference group consisted of all children born in Malmoe during 1980—2005. Obstetric sub-optimality (prematurity, low Apgar scores, growth restriction, or macrosomia) was positively associated with autism but not with Asperger syndrome. Maternal birth outside the Nordic countries was positively associated with autism (adjusted OR: 2.2; 95%CI: 1.6—3.1) and negatively associated with Asperger syndrome (OR: 0.6; 95%CI: 0.3—0.97). The highest risk estimate for autism was found among children to women who were born in sub-Saharan Africa (OR: 7.3), or in East Asia (OR: 3.4).