Paula Rantakallio

Risk factors for recurrent acute otitis media and respiratory infection in infancy

Using a cohort-based design and random enrollment, the relation of various risk factors to acute otitis media, respiratory infection and wheezy bronchitis was studied in 2512 children from the fetal period to the age of two years. The complex interrelations of the risk factors with each other were separated out by multivariate analysis, and the confounding effects of antenatal parameters were also standardized. Acute otitis media with effusion (AOME), as demonstrated by myringotomy, was analyzed as a specific subgroup of acute otitis media (AOM). Day care in local authority nursery was the major risk factor for both types of acute otitis media. The odds ratio (OR) for such children becoming otitis-prone (greater than or equal to 3 episodes of AOME) was 1.8 (95% confidence interval, 1.4-2.2). Short duration of breastfeeding involved another significant risk of recurrent respiratory infections and otitis media, the OR for AOME being 1.5 (1.1-2.0) and that for recurrent respiratory infection 1.3 (1.1-1.6). Allergy and family day care were also significantly associated with infective parameters, but to a lesser extent. The risk factors for wheezy bronchitis were the same as for infections, indicating that wheezy bronchitis is closely related to infections.

The occurrence of acute otitis media in infants. A life-table analysis

A random sample of 2512 children were monitored to an average age of two years to determine the occurrence of acute otitis media (AOM). A life-table methodology was employed in the analysis. The cumulative incidence of the first episode of AOM up to 12 months of age was 42.4% (95% confidence interval 40.4-44.4) and the corresponding figure up to 24 months of age was 71.0% (68.9-73.1). The incidence rate for all acute otitis media episodes was 0.93 episodes per child per year (0.90-0.96) during the first 24 months of life increasing in the spring and autumn. The risk of experiencing an episode of acute otitis media increased at the age of 6-12 months and decreased slowly during the second year of life. The results confirm the frequent nature of acute otitis media and stress the necessity for clear, consistent definition of the criteria for acute otitis media in epidemiological research.

A 14-Year Follow-Up of Children with Normal and Abnormal Birth Weight for Their Gestational Age.: A Population Study

ABSTRACT. Mortality, major neurological handicaps‐including mental retardation, cerebral palsy and epilepsy‐educational subnormality and height at 14 years of age were studied by birth weight percentiles in a birth cohort of 12000 children from northern Finland. Infant mortality was significantly higher below the mean ‐2 SD, 10th and 25th percentiles, than in the median class, from 25th to 75th percentiles, but mortality from one to 14 years only in the lowest weight class. Educational subnormality, including mental retardation ± some other handicap, was highly significantly more frequent in all the percentile classes lower than the median class but showed no significant tendency to be less frequent in the percentiles over the median. It was also highly significantly more frequent among the preterm than the term infant. The number of children with a major neurological handicap but normal school performance did not vary significantly by birth weight percentiles or by gestational age. Height at 14 years increased significantly by birth weight percentiles. The height of the boys with birth weight mean ‐ and +2 SD was nevertheless within the 25th‐75th percentiles for height at 14 years in general, while the height of the girls came close to these percentile limits. The preterm infants were significantly shorter than the term infants at 14 years.

The single parent family and the child's mental health

The prevalence of psychiatric and psychosomatic disorders in a 1 year birth cohort from northern Finland followed up until 19 years was examined on the basis of hospital records and national registers for subsidies for chronically sick children. Psychiatric disorders were found to occur with higher frequency in children of single parent families, especially those lacking a father during the childs whole life. Childhood enuresis was most frequent in the children who had experienced the divorce of their parents. Discriminant function analysis was used to establish the explanatory value of the family constellation for both psychiatric disorders and enuresis. The other significant explanatory variables for psychiatric disorders were school performance, place of residence and the childs height at 1 year of age, with poor school performance, high population density and short stature increasing the risk. The other significant variables increasing the risk of enuresis were psychiatric disorders, poor school performance, juvenile smoking and small size of dwelling. Disabled children had psychiatric disorders 9 times as frequently as non-disabled ones.

Risk factors for mental retardation.

Risk factors for mental retardation were studied prospectively in 12 000 children born in northern Finland in 1966 and followed to the age of 14 years. The number of untraced children was less than 2 per 1000. Altogether 326 children had an IQ less than 86, and the incidence of severe retardation (IQ less than 50) was especially high. An incidence figure for children with mental retardation, a separate figure for healthy children, and also the death rate were calculated for each disease. Only in the cases of Downs syndrome and some hereditary diseases were all the exposed children mentally retarded; in other diseases some children did not seem to suffer any sequelae. A risk factor could be found for 50.6% of the total number of children with mental retardation, the percentage decreasing from the severest to the mildest form (86.7%, 45.4%, and 30.9%). Some 9.4% of the healthy children and 77.7% of those who died had had one or more of these conditions. Prenatal conditions were most often associated with severe mental retardation (64%), and perinatal conditions with mild retardation, (IQ 50 to 70; 27%) and mental subnormality (IQ 71 to 85; 18%). Cases with no known risk factor were more common among boys than girls.

PROGNOSIS FOR LOW-BIRTHWEIGHT INFANTS UP TO THE AGE OF 14: A POPULATION STUDY

A birth cohort of 12,058 infants was followed up to 14 years of age. Cerebral palsy, epilepsy, severe hearing defects, mental retardation and educational subnormality all had a higher incidence among the 411 children with a low birthweight (<2500g). 6 per cent of the total cohort had educational problems with or without some other neurological handicap, and there was a higher prevalence among low‐birthweight infants. 1.5 per cent had a handicap but normal school performance. Children with birthweight 1500 to 2499g had a significantly higher percentage of handicaps than those of heavier birthweight. All the neurological handicaps were more common among boys than girls, but only in mental subnormality was there a marked difference. Height at 14 years was significantly less among low‐birthweight children.

Prevalence of Hearing Loss at the Age of 15 in a Birth Cohort of 12000 Children from Northern Finland

Hearing losses at the age of 14 years were investigated in a questionnaire administered to 11 780 children born in northern Finland and followed up since pregnancy. The untraced cases numbered 20, or 1.7 per 1 000. Audiometry screening results from the schools were obtained from 97.2% of the 425 children who were reported to suffer from hearing loss and a random sample of 959 children with normal hearing. When the figures were calculated to represent the whole material of 11 748 cases, marked hearing loss, PTA greater than 25 dB in the better ear, was found in 64 children, 0.5%, minor loss, greater than 20 dB at 4 kHz but PTA less than 25 dB in the better ear, in 420 children, 3.6%, and slight abnormality, greater than 20 dB, at any frequency in 1 224, 10.4%. 17.6% of the boys and 11.8% of the girls had some kind of hearing loss. Eight children were deaf in both ears and 11 in one ear, and 16 children were severely impaired in at least one ear (PTA greater than or equal to 60; less than 90 dB).

Perinatal risk for infants of unmarried mothers over a period of 20 years

The perinatal events of the infants of 444 unmarried mothers, 3.7% of the total Northern Finland birth cohort from 1966, were compared with those of infants of 11,525 married mothers (95.5%), and a similar comparison was made between 395 (4.2%) unmarried mothers and 7516 (80.3%) married mothers in a second Northern Finland birth cohort in 1985-86. 1336 mothers, 14.3% of the mothers in this later cohort, were cohabiting. Divorced and widowed mothers were excluded from both cohorts. The infants of the unmarried mothers had a significantly lower mean birth weight, were more likely to be small for their gestational age (SGA), of low birth weight (LBW) (below 2500 g) and had a higher incidence of pre-term births than those of the married mothers in both cohorts. Perinatal mortality was significantly higher among the unmarried mothers only in the former cohort. These differences in perinatal events diminished markedly after adjustment for maternal age, parity, height, years of schooling and smoking habits, but did not totally disappear. The difference in the incidence of pre-term births diminished, but remained significant in both cohorts. The difference in mean birth weight, in the incidence of LBW infants and in perinatal mortality remained significantly less favourable to the unmarried mothers only in the 1966 cohort. It seems that the gap between the married and unmarried mothers had diminished. The incidence of SGA infants did not differ significantly between the married and unmarried mothers in either cohort after adjustment for the background variables. The cohabiting mothers formed an intermediate group between the married and single unmarried mothers in respect of perinatal events, but were close to the married mothers. In raw figures, the mean birth weight in this group was significantly lower and the incidence of SGA infants higher than among the married mothers, but these differences also disappeared after adjustment of the background variables.

Is a child's history of acute otitis media and respiratory infection already determined in the antenatal and perinatal period?

A random sample of 2512 children were followed up from fetal period to the age of two years and the relation of various antenatal and perinatal factors to acute respiratory infection, wheezy bronchitis and otitis media was studied. A model containing the relationships between the variables was used as a basis for the analysis and the powerful confounding effects of postnatal factors were standardized. Acute otitis media with effusion (AOME) demonstrated by myringotomy was analyzed as a specific subgroup of acute otitis media (AOM). Low birth weight (less than or equal to 2500 g) and prematurity (birth before the 37th gestational week) did not influence either AOM or AOME. The odds ratio for low birth weight infants becoming otitis-prone (greater than or equal to 3 episodes of AOME) was 1.5 (0.9-2.1, P greater than 0.1). The various neonatal ventilation therapies were not associated with either AOM or AOME, but intermittent positive pressure ventilation, low birth weight and prematurity were distinctly related to wheezy bronchitis. The odds ratio regarding intermittent positive pressure ventilation was 2.0 (1.0-3.0, P less than 0.05) and that regarding low birth weight 1.7 (1.0-2.3, P less than 0.05). Boys had a slightly increased risk with respect to all the infective parameters. Birth order was closely correlated with the infective parameters, but much of this correlation was due to the postnatal effect of siblings. Altogether the antenatal and perinatal factors had only a slight effect on the infective parameters studied.

Inequalities in children's deaths in the country with thelowest infant mortality?

Abstract Social class differences in childhood mortality up to the age of 16 years are studied in aNorthern Finland birth cohort of 12,000 children born in 1966. A clear social class difference is seen in infant mortality, but the discrepancy is only slight for the older age groups in terms of mortality from all causes. Social class differences are clearest in infectious and perinatal diseases. Mortality is found to be significantly higher among the children of farmers than among the rest in all age groups due to regional and sociocultural factors such as an excess of older mothers.