Anders Ericson

A Quality Study of a Medical Birth Registry

A quality control study was made of the Swedish Medical Birth Registry. This registry used one mode of data collection during 1973-1981 and another from 1982 onwards. The number of errors in the register was checked by comparing register information with a sample of the original medical records, and the variability in the use of diagnoses between hospitals was studied. Different types of errors were identified and quantified and the efficiency of the two methods of data collection evaluated.

Very low birthweight boys at the age of 19

Using linked data from the Swedish Medical Birth Registry and the National Service Enrolment Register, long term follow up (to 18–19 years age) was made of 260 surviving singleton boys whose birthweight was less than 1500 g from a total of 150 229 boys born between 1973–5. These boys were shorter and lighter than boys who weighed more at birth, they had more visual and hearing impairments, were at much higher risk of cerebral palsy and other signs of mental impairment, evident as lower intelligence test scores and shorter schooling. No significant excess of asthma, back problems, or headaches were found.

Cigarette smoking as an etiologic factor in cleft lip and palate.

A case-control study has been made on smoking habits in women who, during 1975, gave birth to infants with closure defects of the central nervous system (ASB) or with cleft lip or cleft palate (CLP). For each case, two control subjects with nonmalformed infants were selected and matched for delivery unit, time of delivery, maternal age, and maternal parity. Smoking habits were routinely included in hospital records at first visit to a maternity health clinic during pregnancy. Data were studied for 66 cases of CLP, 66 cases of ASB, and 261 control subjects. Significantly more women who had infants with CLP smoked than did control women, but women with ASB infants showed a normal smoking pattern. Drug use did not explain the findings. It is suggested that maternal smoking is one of many factors of importance in the etiology of cleft lip and cleft palate in humans.

Nonsteroidal anti-inflammatory drugs in early pregnancy.

A study was performed of congenital malformations in infants whose mothers used nonsteroidal anti-inflammatory drugs (NSAIDs) in early pregnancy. Data were obtained from an ongoing prospective recording of drug use during the first trimester. During the period July 1, 1995 through December 31, 1998, 2557 infants were born to women who reported the use of NSAIDs in early pregnancy. The OR (after consideration of maternal age, parity, and smoking habits) for any congenital malformation was 1.04 (95%CI 0.84-1.29), but the OR for cardiac defects reported to the Medical Birth Registry was 1.86 (1.32-2.62) based on 36 instances, and for orofacial clefts 2.61 (1.01-6.78) based on only six instances. By using other information sources, another four infants with cardiac defects were identified. There was no drug specificity for cardiac defects but among six mothers of infants with orofacial clefts, five had used naproxen.

Pregnancy outcome in women working as dentists, dental assistants or dental technicians

SummaryPregnancy outcome in women with work in dentistry was studied using various central health registries. A total of 8157 infants born of dentists, dental assistants, or dental technicians in 1976 or 1982–1986 in Sweden were studied with respect to perinatal survival, low birthweight, and malformations and compared with all births. The only deviating finding was that of a significantly low perinatal death rate. Specifically, no increase in a risk for spina bifida was seen and the upper 95% confidence limit for the risk ratio was 2.1. A study was also made of hospitalized spontaneous abortions in women with these occupations in the years 1980–1981. No significant deviations from expected values were found. In a small study of only 78 such pregnancies in 1964–1965, no increase in spontaneous abortion rate was seen. Only one infant was malformed (anencephaly): both its parents worked as dental technicians. None of the mothers of 220 infants with a neural tube defect born in 1965–1967 in Sweden was a dentist. We find no indications that this occupation represents a significant reproduction hazard at the present time in Sweden.

Pregnancy Outcome and Social Indicators in Sweden

ABSTRACT. Perinatal mortality, birth weight, the distribution of gestational age, and the relationship between gestational age and birth weight have been studied with regard to births reported to the Register of Births during 1976–77. In order to determine the influence of socio‐economic factors on the parameters studied, the information from the birth register has been combined with that from the 1975 census in Sweden (including occupation of the mother, income of the family, type of family and housing standard). The total population of 190024 infants was divided into three groups; 6915 infants (3.6 %) were assigned to the most privileged group (group I) and 26430 (13.9 %) to the less privileged group (group III). The perinatal mortality rate did not differ significantly between group I and III. A comparison of the three groups showed a socio‐economic difference as regards birth weight and the incidence of preterm as well as of postterm births. The less privileged group had a greater proportion of infants of low birth weight and of infants that were small for gestational age.

Surveillance of smoking during pregnancy in Sweden, 1983-1987

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.

Delivery Outcome of Women Working in Laboratories during Pregnancy

By record-linkage of the 1975 Swedish census and the Medical Birth Register of infants born in 1976, 1,161 infants were identified who were born to women coded as laboratory workers in the census. These infants were compared to all 98,354 infants born in Sweden in 1976. There was a higher than expected number of infants who died neonatally and/or had congenital malformations. Twenty-six singleton infants who either died or had serious malformations were selected for further study. To each of the cases, 2 controls were selected among the 1,161 infants. A questionnaire was sent to the 26 cases and 50 controls (2 cases had only 1 control each) asking about work during pregnancy. No specific type of laboratory work was found to be more common among the cases than controls.

Socio-economic variables and pregnancy outcome. 2. Infant and child survival.

ABSTRACT. The effects of various social indicators on infant and child mortality were studied in Sweden with the use of a medical birth register to which census information was linked. Two years were studied: 1976 births linked to the 1975 census, and 1981 births linked to the 1980 census. Survival was followed to the age of 5 by linkage of the birth register with the death certificate register. The only statistically significant effect of a single socio‐economic variable was that of housing conditions on perinatal death rate and postperinatal death rate up to the age of one. The family situation (e. g., cohabitation or not) had some effect, although it was not statistically significant. On the basis of cohabitation status and other social indicators, including housing conditions, we selected two groups: one privileged and the other underprivileged. Using crude mortality rates, we found no definite difference. There was evidence that the mortality rate had decreased more between 1976 and 1981 in the privileged than in the underprivileged group, but the difference may have been coincidental. After standardization for maternal age and parity, however, a difference appeared with a ratio of 1.14 between the underprivileged and the privileged groups, which was valid for deaths up to the age of one. After that age, no difference was seen. Following standardization for birthweight, the opposite was found: a higher weight‐specific mortality rate in the privileged group than in the underprivileged group. The interpretation of these findings is discussed.

Socio-economic Variables and Pregnancy Outcome Birthweight in Singletons

Ericson, A., Eriksson, M., Källén, B. and Zetterström, R. (The National Board of Health and Social Welfare, Department of Paediatrics, St. Görans Hospital, Stockholm, and Department of Embryology, Lund, Sweden). Socio‐economic variables and pregnancy outcome. Birthweight in singletons. Acta Paediatr Scand Suppl 360: 48, 1989.