OBJECTIVES--To investigate whether childhood cancer is associated with intramuscular administration of vitamin K to newborn infants. DESIGN--Routines for administration of vitamin K to infants born after normal deliveries during 1973-89 were obtained from maternity hospitals. Occurrence of cancer up to the end of 1991 was identified by comparing these records with the national cancer registry. Adherence to the routine method of administering vitamin K was checked with the medical records of a sample of 396 infants (196 who had developed childhood cancer and 200 controls). SETTING--All maternity hospitals in Sweden. SUBJECTS--1,384,424 full term infants born after non-instrumental deliveries, 1,085,654 of whom were born in units where vitamin K was routinely given by intramuscular injection and 272,080 of whom were born where it was given orally. MAIN OUTCOME MEASURES--Odds ratios for cancer after intramuscular administration of vitamin K versus oral administration after stratification for year of birth. RESULTS--Adherence to routine method of administering vitamin K was 92% in the 235 cases where individual information could be found. The risk of cancer after intramuscular administration of vitamin K was not elevated compared with that after oral administration: odds ratios of 1.01 (95% confidence interval 0.88 to 1.17) for all childhood cancers and 0.90 (0.70 to 1.16) for childhood leukaemia. CONCLUSIONS--The alleged association between intramuscular vitamin K prophylaxis to newborn infants and childhood cancer could not be verified in the present study of full term infants born after non-instrumental delivery.
A case-control study on work with video screen equipment during pregnancy has been made for three cohorts of women, identified with the aid of occupational codes in the census, linked to the Medical Birth Registry and a registry containing information on women hospitalized for spontaneous abortion. Five hundred and twenty-two cases were selected (women with spontaneous abortions or women who had infants that died, had severe malformations, or had a birth-weight below 1,500 g) and 1,032 controls (women who had infants without any of these characteristics) taken from the same age stratum as the cases. All pregnancies had occurred in 1980-81. Questionnaires were mailed to the women asking for information on their work situation, including questions about work with video screen equipment. Fifty-eight women were excluded for various reasons. Response rate was 93%--lower (89%) among women with spontaneous abortions than among women who gave birth (95%). As stress and smoking were associated with video screen work, the effect of video screen work was analyzed after stratification for stress and smoking--no statistically significant effect of video screen work was seen but odds ratios were above 1. Crude odds ratios for video screen work were significantly elevated and showed a dose-dependent effect. This finding is discussed from the point of view of biases in the study: selective non-responding, recall bias, geographical variability, and lack of information on women who had induced abortions. Using questionnaire data for exposure rates in the populations studied, an estimate of the effect greater than or equal to 10 hr weekly work with video screens on spontaneous abortion rate was made. The point estimate was 1.04 with a 95% confidence interval of 0.9-1.2. Analysis of 44 infants with birth defects whose mothers had worked more than 10 hr/week with video screen equipment compared to 30 infants with birth defects whose mothers had not used such equipment in early pregnancy showed no signs of specificity in the type of birth defect.
Data from three Swedish health care registries--the Medical Birth Registry, the Registry of Congenital Malformations, and the Hospital Discharge Registry--were linked for the 9-year period 1973-1981 to identify women who had appendectomy during pregnancy and their offspring, and to determine several pregnancy outcomes (gestational duration, birth weight, perinatal mortality, and congenital anomalies). Among the 720,000 deliveries during this period, 778 were complicated by appendectomy (one in 936), and the diagnosis of appendicitis was confirmed in 64% of the cases (one in 1440). Significant findings included: 1) an increase in the risk of delivery the week after appendectomy when the operation was performed after 23 weeks' gestation, with no further increase if the pregnancy continued beyond 1 week; 2) a decrease in mean birth weight of 78 +/- 24 g with more infants than expected weighing less than 3000 g; 3) an increase in the number of live-born infants dying within 7 days of birth; 4) no increase in the number of stillborn infants; and 5) no increase in the number of congenitally malformed infants.
A medical birth registry was used for a geographical analysis of birth weight distribution. Nearly 900,000 Swedish singleton births, 1973-1981, were used for an analysis of the effect of some variables and for standardization for these variables. A marked change in the rate of low birth weight infants (LBW, less than 2,500 g) was seen in the country between 1976 and 1977. A U-formed effect of maternal age and of parity was demonstrated. A marked interaction between the effects of these two variables existed. Two social groups were compared and the well-known high rate of LBW infants associated with low socioeconomic conditions was demonstrated. Standardization for the variables mentioned influenced this effect only little but reduced the difference between the social groups concerning infants above 3.5 kg weight. The background data were used for analysis of restricted geographical areas.
PURPOSE: To investigate the influence of maternal antiepileptic drug (AED) treatment on pregnancy duration, birth weight, body length, head circumference, and intrauterine growth in infants exposed in utero to antiepileptic drugs in Sweden between 1973-1997, with 963 singleton infants. METHODS: Data collected from (a) 1973-1981 (record linkage between a hospital discharge register and a medical birth register); (b) 1984-1995 (prospectively collected information in one defined catchment area with two delivery hospitals); and (c) 1995-1997 (medical birth register data). Observed numbers of infants below a defined size for body measurements compared with expected numbers calculated from all births in Sweden after stratification for year of birth, maternal age, parity, and education or smoking habits in early pregnancy. Standard deviation scores estimated with same stratification procedures. RESULTS: Fraction of monotherapy exposures increased from approximately 40% to approximately 90% from 1973 to 1997. Significantly increased numbers of infants with small body measurements found in exposed group. Negative influence on body dimensions decreased over time. More marked effects found in infants exposed to polytherapy. In monotherapy, only infants exposed to carbamazepine consistently showed reduction in body dimensions. Significant effect on gestational age in girls and on number of small for gestational age (
To investigate whether factors in the fetal or neonatal period influence the risk of later development of coeliac disease we conducted a population-based register study. The Swedish Medical Birth Register was linked with the Hospital Discharge Register and identified 3392 singleton infants born in the period 1987-97 who developed coeliac disease. Perinatal data for these children were compared with all children born in these years. Exposure variables: Maternal age, parity and smoking habits in early pregnancy, preeclampsia, pregnancy duration and birthweight, birthweight by gestational week, Apgar score, neonatal icterus, neonatal infections, maternal-fetal blood group incompatibility, exchange transfusion, phototherapy. Odds ratios and test-based confidence intervals were calculated. Analyses were made with stratification for year of birth and other risk factors. The risk of developing coeliac disease decreased with maternal age and was lower in first-born than in second-born children. Maternal smoking in early pregnancy was a weak risk factor, as was low birthweight. The most evident risk factors were being exposed to neonatal infections (OR = 1.52, confidence limits 1.19: 1.95) and being small for gestational age (OR = 1.45, confidence limits 1.20; 1.75). These risk factors were independent of each other. Conclusions: We have demonstrated that the intrauterine environment, mainly as mirrored by a low birthweight for gestational age and, independently, neonatal infection diagnosis, is associated with the risk of developing coeliac disease, supporting the idea of a multifactorial aetiology of the disease.
Concerns have been expressed about possible adverse effects of the use of antidepressant medication during pregnancy, including risk for neonatal pathology and the presence of congenital malformations.
Data from the Swedish Medical Birth Register (MBR) from 1 July 1995 up to 2007 were used to identify women who reported the use of antidepressants in early pregnancy or were prescribed antidepressants during pregnancy by antenatal care: a total of 14 821 women with 15 017 infants. Maternal characteristics, maternal delivery diagnoses, infant neonatal diagnoses and the presence of congenital malformations were compared with all other women who gave birth, using the Mantel-Haenszel technique and with adjustments for certain characteristics.
There was an association between antidepressant treatment and pre-existing diabetes and chronic hypertension but also with many pregnancy complications. Rates of induced delivery and caesarean section were increased. The preterm birth rate was increased but not that of intrauterine growth retardation. Neonatal complications were common, notably after tricyclic antidepressant (TCA) use. An increased risk of persistent pulmonary hypertension of the newborn (PPHN) was verified. The congenital malformation rate was increased after TCAs. An association between use of paroxetine and congenital heart defects was verified and a similar effect on hypospadias was seen.
Women using antidepressants during pregnancy and their newborns have increased pathology. It is not clear how much of this is due to drug use or underlying pathology. Use of TCAs was found to carry a higher risk than other antidepressants and paroxetine seems to be associated with a specific teratogenic property.
OBJECTIVE: To study delivery outcome after maternal use of acid-suppressing drugs during early pregnancy. DESIGN: Cohort study of women identified by interview in early pregnancy. POPULATION: Sweden women giving birth from 1995 to early 1997. METHODS: Comparison of infants exposed to acid-suppressing drugs with all births in 1995-1996. MAIN OUTCOME MEASURES: Presence of congenital malformations. RESULTS: Proton pump blockers were used by 275 women, H2 receptor antagonists by 255 women, and both categories of drugs by 20 women. No effect of the use of omeprazole or H2-receptor antagonists on the rate of congenital malformations could be demonstrated. CONCLUSIONS: Though a teratogenic effect of these drugs cannot be completely ruled out, the individual risk after exposures during the first trimester seems to be negligible.
Parental exposure in chemical industry may represent a risk for pregnancy outcome. Using a population-based medical birth registry, linked to census for 3 years (1976, 1981, 1986), delivery outcome has been studied in women who worked as factory workers in chemical industry or whose cohabiting partners had such work. As a group of reference were used all women who worked in industry and all women whose partners worked as factory workers, respectively. No increased rate of abnormality was seen in infants fathered by men working in chemical industry. Infants born of women working in such industry showed a high rate of low birth weight and short gestational length and also of infant death. The latter phenomenon was only seen among infants born in 1976.
A study was made of the delivery outcome in women working in medical occupations in Sweden. One cohort of approximately 1500 women who worked in 31 hospitals for chronic diseases during the period 1965-1975 and who gave birth during those years was studied. Also all women working in medical occupations and delivered during the years 1973-1975 were investigated by matching existing data registers. It was found that caesarian sections and vacuum extractions were used more frequently than expected. A significantly increased perinatal death rate was noted in 1973, but could not be related to any specific occupational exposure known to represent an increased risk. No general increase in malformation rate was seen, but a local cluster, occuring at certain hospitals in the Gothenburg area in 1973-1974 was identified. No support was obtained for the hypothesis that the use of soap containing hexachlorophene is associated with an increased risk of perinatal death or malformation.