The declining number of live births, surgical abortions, and the relatively unchanged number of spontaneous abortions in Denmark during a 5 year period in 1977-1981 are analyzed. The health care system and hospitals provided statistical data for this study. The number of live births decreased by approximately 14% from 1977 to 1981 (62,247 - 53,370); however, conceptions also fell 16% during the period 1973/74 - 1980/81 (100,000 - 84,000). The rate of conception was 82/1000 fertile women in 1976-77, but only 69/1000 in 1980-81. Legally induced abortions were significantly fewer in 1979 (23,378) than in 1977 (26,402); nevertheless, in 1980-81 about 30% of all pregnancies were terminated. For this same year, a decrease in the number of abortions was noticeable in the 25-34 year age group, but an increase from 54% to 60% was observed in the under 20 year age group. The fertility pattern was greatly influenced by the declining number of pregnancies in the 20-29 year age group, since they give birth to 70% of the newborns. In 1981, the birth rate fell about 8% (or 4000 births), and the number of abortions dropped by 800 or 2%. The figures for 1982 indicate a 2% decline in births and a decrease in abortions of 1000. Age group-specific adjustment of these figures will reveal whether or not this trend will continue.
We investigated the geographical distribution of birthweights among liveborn infants in Denmark for the years 1979-1983, using the Medical Birth Register of the Danish National Board of Health. The investigation includes 272,361 liveborn children. The birthweight varies with the sex of the child, and with the age and parity of the mother. In the analysis of geographical variation of birthweight correction was made for these factors. We found an association between birthweight and urbanization, the lowest average birthweight being found in the capital, and the highest in the rural areas. Further, the average birthweight was higher in the western than in the eastern part of Denmark, especially in Northern Jutland and in Aarhus County. Geographical variation in gestational age explains part of the geographical variation in birthweight, but part of the variation must be explained by variation in the growth of fetuses. The role of genetic variation, variation in living conditions, and variation in the conduct of the health services is discussed. We found an unexpected association between the average birthweight in the counties, and neonatal mortality; the counties with high average birthweights also had a significantly increased neonatal mortalities.
Birthweights in the Faroe Islands are among the highest in the world. Compared with Denmark, the average birthweight of liveborn singleton infants of primiparous mothers is 194 g higher, and a substantial part of this difference seems to be attributable to longer gestation. Prostaglandins play an important part in the timing of parturition in human beings. Dietary (n-3)-polyunsaturated fatty acids (PUFA) in high amounts influence endogenous prostaglandin metabolism. Owing to the large consumption of marine fat, the average intake of (n-3)-PUFA in the Faroes by far exceeds that in Denmark. The hypothesis proposed is that dietary (n-3)-PUFA in high amounts prolong gestation in human beings by interfering with uterine production of prostaglandins, possibly by inhibiting the production of dienoic prostaglandins, primarily PGF2 alpha and PGE2, which are mediators of uterine contractions and cervical ripening.