Dag Moster

Long-Term Medical and Social Consequences of Preterm Birth

BACKGROUND Advances in perinatal care have increased the number of premature babies who survive. There are concerns, however, about the ability of these children to cope with the demands of adulthood. METHODS We linked compulsory national registries in Norway to identify children of different gestational-age categories who were born between 1967 and 1983 and to follow them through 2003 in order to document medical disabilities and outcomes reflecting social performance. RESULTS The study included 903,402 infants who were born alive and without congenital anomalies (1822 born at 23 to 27 weeks of gestation, 2805 at 28 to 30 weeks, 7424 at 31 to 33 weeks, 32,945 at 34 to 36 weeks, and 858,406 at 37 weeks or later). The proportions of infants who survived and were followed to adult life were 17.8%, 57.3%, 85.7%, 94.6%, and 96.5%, respectively. Among the survivors, the prevalence of having cerebral palsy was 0.1% for those born at term versus 9.1% for those born at 23 to 27 weeks of gestation (relative risk for birth at 23 to 27 weeks of gestation, 78.9; 95% confidence interval [CI], 56.5 to 110.0); the prevalence of having mental retardation, 0.4% versus 4.4% (relative risk, 10.3; 95% CI, 6.2 to 17.2); and the prevalence of receiving a disability pension, 1.7% versus 10.6% (relative risk, 7.5; 95% CI, 5.5 to 10.0). Among those who did not have medical disabilities, the gestational age at birth was associated with the education level attained, income, receipt of Social Security benefits, and the establishment of a family, but not with rates of unemployment or criminal activity. CONCLUSIONS In this cohort of people in Norway who were born between 1967 and 1983, the risks of medical and social disabilities in adulthood increased with decreasing gestational age at birth.

Cesarean Section and Risk of Severe Childhood Asthma: A Population-Based Cohort Study

OBJECTIVE To explore the possible association between delivery by cesarean section (CS) and later development of asthma. STUDY DESIGN A population-based cohort study of 1,756,700 singletons reported to the Medical Birth Registry of Norway between 1967 and 1998, followed up to age 18 years or the year 2002. Exposure was the mode of delivery (spontaneous vaginal, instrumental vaginal, or CS, with planned and emergency CS separately from 1988 onward). Outcome was asthma registered in the National Insurance Scheme, which provides cash benefits to families of children with severe chronic illnesses. We used multivariate Cox proportional hazard models to examine associations between exposure and outcome. RESULTS The cumulative incidence of asthma was 4.0/1000. Children delivered by CS had a 52% increased risk of asthma compared with spontaneously vaginally delivered children (adjusted hazard ratio [HR] = 1.52; 95% confidence interval [CI] = 1.42 to 1.62). Between 1988 and 1998, planned and emergency CS was associated with a 42% (HR = 1.42; 95% CI = 1.25 to 1.61) and 59% (HR = 1.59; 95% CI = 1.44 to 1.75) increased risk of asthma, respectively. CONCLUSION We found a moderately increased risk of asthma in the children delivered by CS. The possibly stronger association with emergency CS compared with planned CS could be worth pursuing to investigate possible causal mechanisms.

Joint association of Apgar scores and early neonatal symptoms with minor disabilities at school age

Objective: To examine whether the combination of a low five minute Apgar score and symptoms of neonatal encephalopathy is associated with minor impairments at school age. Design: Population based cohort study. Setting: Norway. Participants: All 727 children of the cohort were born between 1983 and 1987, had normal birth weights, no congenital malformations, and no major neurological abnormalities. The cohort comprised three groups with five minute Apgar scores of 0–3, 4–6, and 7–10, and were followed from birth to 8–13 years of age by combining data from The Medical Birth Registry, questionnaires, hospital discharge summaries, and the National Insurance Scheme. Main outcome measure: Neurodevelopmental impairments such as learning, behavioural, and minor motor difficulties. Results: Children with a five minute Apgar score of 3 or less and signs consistent with neonatal encephalopathy had a significantly increased risk of developing minor motor impairments (odds ratio (OR) 12.8, 95% confidence interval (CI) 2.6 to 63.2), epilepsy (OR 7.0, 95% CI 1.3 to 39.2), need of extra resources in kindergarten (OR 7.0, 95% CI 1.3 to 39.2) or at school (OR 3.4, 95% CI 1.8 to 6.3), and had reduced performance in reading (OR 4.6, 95% CI 2.3 to 9.5) and mathematics (OR 3.3, 95% CI 1.5 to 7.3), compared with children with normal Apgar scores and no neonatal symptoms. They also more often had problems related to tractability, aggressivity, passivity, anxiety, academic performance, and fine motor development. Conclusion: Children with low Apgar scores and subsequent signs of cerebral depression who do not develop cerebral palsy may still have an increased risk of developing a variety of neurodevelopmental impairments and learning difficulties.

Growth references for Norwegian children

BACKGROUND The growth charts currently used in Norway, are based on measurements from the 1970s and 80s. New data are available from the Bergen Growth Study collected in 2003 - 6. In 2006, WHO published international charts for 0-5 year-old children. MATERIAL AND METHODS New growth charts based on data from the Bergen Growth Study and the Medical Birth Registry of Norway are presented for children aged 0-19 years. These were compared with existing references and with the WHO curves. RESULTS Norwegian children aged 0-4 years have length, height and weight measurements that are only marginally different from those in the Norwegian growth charts in current use. In older children there has been an increase in the 50-percentile for height up to 3.4 cm in boys and 2.5 cm in girls. For children older than four years, weight for height has increased, especially for the upper percentiles. The percentile lines in the new Norwegian reference are generally positioned above the WHO standard for weight at birth, and for length/height, weight and head circumference in the age group 6 months to 5 years. INTERPRETATION The secular trends in growth mirror the need for new charts. The fact that Norwegian children differ from the WHO standards may reflect population differences relating to environment or growth potential between the populations.

Growth references for 0–19 year-old Norwegian children for length/height, weight, body mass index and head circumference

Background: Previous growth references for Norwegian children were based on measurements from the 1970s and 1980s. New reference data, collected through the Bergen Growth Study and the Medical Birth Registry of Norway, are presented as LMS values. Materials and methods: A cross-sectional sample of children aged 0–19 years in stratified randomized design measured in 2003–2006 as a part of the Bergen Growth Study (n = 7291) and birth data of children born in 1999–2003 from the Medical Birth Registry of Norway (n = 12 576) was used to estimate the new references by the means of the LMS method. Measurement reliability was assessed by test-rest studies. Results: New references were constructed for length/height, weight, body mass index (BMI) and head circumference. Length/height and weight for children aged 0–4 years were similar to previous Norwegian references, but mean height increased up to a maximum of 3.4 cm in boys and 2.5 cm in girls during the pubertal years. Mean height was similar to (or slightly higher) in comparison with other recent European references. Reliability of the measurements compared well with published estimates. Conclusion: Because of the observed secular trends in growth, it is advised to use the new references, which have been endorsed by the Norwegian Department of Health.

Pulse oximetry screening as a complementary strategy to detect critical congenital heart defects.

Objective: To compare strategies with and without first‐day of life pulse oximetry screening to detect critical congenital heart defects (CCHDs).

Relation between size of delivery unit and neonatal death in low risk deliveries: population based study

AIM To examine risk of neonatal death after low risk pregnancies in relation to size of delivery units. METHODS A population based study of live born singleton infants in Norway with birthweights of at least 2500 g was carried out. Antenatal risk factors were adjusted for. RESULTS From 1972 to 1995, 1.25 million births fulfilled the criteria. The neonatal death rate was lowest for maternity units with 2001–3000 annual births and steadily increased with decreasing size of the maternity unit to around twice that for units with less than 100 births a year (odds ratio 2.1; 95 % confidence interval 1.6 to 2.8). Institutions with more than 3000 deliveries a year also had a higher rate (odds ratio 1.7; 95% CI 1.4 to 2.0), but analyses suggest that this rate is overestimated. CONCLUSION Around 2000 to 3000 annual births are needed to reduce the risk of neonatal deaths after low risk deliveries.

Risk of cerebral palsy in relation to pregnancy disorders and preterm birth: a national cohort study.

To assess the risk of developing cerebral palsy in relation to pregnancy disorders and preterm birth.

Neonatal mortality rates in communities with small maternity units compared with those having larger maternity units

Objective To compare neonatal mortality in geographical areas where most deliveries occur in large hospitals with areas where a larger proportion of deliveries occur in small maternity units.

Immediate Treatment Versus Sonographic Surveillance for Mild Hip Dysplasia in Newborns

OBJECTIVE: We conducted a blinded, randomized, controlled trial to examine whether mildly dysplastic but stable or instable hips would benefit from early treatment, as compared with watchful waiting. PATIENTS AND METHODS: A total of 128 newborns with mild hip dysplasia (sonographic inclination angle [α angle] of 43°–49°) and stable or instable but not dislocatable hips were randomly assigned to receive either 6 weeks of abduction treatment (immediate-treatment group) or follow-up alone (active-sonographic-surveillance group). The main outcome measurement was the acetabular inclination angle, measured by radiograph, at 1 year of age. RESULTS: Both groups included 64 newborns, and there was no loss to follow-up. With the exception of a small but statistically significant excess of girls in the active-sonographic-surveillance group, there were no statistically significant differences in baseline characteristics between the 2 groups. The mean inclination angle at 12 months was 24.2° for both groups (difference: 0.1 [95% confidence interval (CI): −0.8 to 0.9]), and all children had improved and were without treatment. The mean α angle was 59.7° in the treatment group and 57.1° in the active-surveillance group for a difference of 2.6° evaluated after 1.5 and 3 months (95% CI: 1.8 to 3.4; P < .001). At 1.5 months of age, the hips had improved in all treated children but not in 5 children under active surveillance (P = .06). Among the sonographic-surveillance group, 47% received treatment after the initial surveillance period of 1.5 months. CONCLUSIONS: Active-sonographic-surveillance halved the number of children requiring treatment, did not increase the duration of treatment, and yielded similar results at 1-year follow-up. Given a reported prevalence of 1.3% for mildly dysplastic but stable hips, a strategy of active surveillance would reduce the overall treatment rate by 0.6%. Our results may have important implications for families as well as for health care costs.