Secular trends in uncertain-sex births and proportion of male births in Norway, 1967-1998

It has been hypothesized that environmental factors influence sex differentiation in the fetus, thus causing a reduced sex ratio (male/female) at birth, an increase in the prevalence of ambiguous-sex infants, and possibly an increase in spontaneous abortion rates. In Norway, subsequent to 1967, all deliveries, including late abortions after 16 wk of gestation, have been reported to the Medical Birth Registry of Norway. The authors used these data to assess birth-weight-specific secular trends of uncertain-sex infants and the proportion of male births, from 1967 through 1998. Total rates of uncertain-sex infants increased from 2.3/10,000 births in 1967 to 8.0/10,000 births in 1998 in the birth weight strata of less than 600 gm. The total proportion of male births was stable; however, there was a reduction in the proportion of male births among births weighing less than 400 gm--from 58.4% to 53.4%. Incomplete ascertainment of abortions may have biased the results, but it would not have accounted for the increased occurrence of uncertain-sex infants and the decreased proportion of males observed among late-term abortions.     

Unwanted and mistimed births in the United States: 1968--1973

Unwanted U.S. marital fertility was down to just nine percent by 1973. The largest proportion of unwanted births was reported by poor black women--23 percent--but this group registered the steepest decline in unwanted childbearing of all the poverty-status and racial groups studied.     

Impact of multiple births and elective deliveries on the trends in low birth weight in Norway, 1967-1995.

To describe trends in low birth weight (less than 2,500 g), the authors analyzed 1.7 million live births and stillbirths registered between 1967 and 1995 in the Medical Birth Registry of Norway. The proportion of low birth weight infants declined from 5.3% in 1967 to 4.5% in 1979 and was followed by a steady increase that reached 5.3% in 1995. Similar trends were observed in the proportion of preterm births. Mean birth weight increased from 3,456 g in 1967 to 3,518 g in 1995. From 1979 to 1987, the increase in the prevalence of low birth weight was related to single births, and after 1987 it was related to multiple births, which increased from 2.3% of all births in 1987 to 3.1% in 1995. The proportion of low birth weight in births occurring after 37 weeks of gestation declined continuously, resulting in low birth weight births' to an increasing extent being made up of births occurring before 37 weeks of gestation. In an ecologic analysis based on county of maternal residence, the increase in low birth weight among single births was accounted for by an increase in deliveries with induction of labor or cesarean section. The authors conclude that the overall proportion of low birth weight births is not a good indicator of health in a population with extensive use of obstetric procedures that affect gestational age or assisted fertilization, which increases the number of multiple births.     

Secular changes in early neonatal mortality in Norway, 1967-1981

Two five-year cohorts, 1967-1971 and 1977-1981, of the Medical Birth Registry of Norway, were utilized to analyze secular trends in early neonatal mortality rates, controlling simultaneously for birth weight, parity, maternal age, and sex. Improvement in the crude early neonatal mortality rate, from 6.5 to 2.9 per 1,000, was partitioned into one portion (18.4%) attributable to changes in the distribution of the birth weight or the other independent variables and another portion (81.6%) attributable to improved survival within each specific subgroup in the multivariate table. The early neonatal mortality rate was found to decrease in all subgroups, the low birth weight groups showing a significantly greater decline than the normal birth weight groups. Women with diabetes, epilepsy, or blood group antibodies were studied in separate analyses. For women with diabetes, the odds ratio of the early neonatal mortality rate between the first and the second periods was found to be three times the odds ratio for women without diabetes, and 2.9% of the total improvement of the crude early neonatal mortality rate was attributable to an improved survival in these infants.     

Induced abortions and births. Trends in seven counties, Norway, 1972-1983

This paper discusses the changes in the frequencies of induced abortions and births according to changes in the abortion legislation in Norway during the 1970s. The study material consists of women aged 15-44 years having undergone induced abortion or giving birth in seven Norwegian counties during the period 1972-83. Since the liberalization of the abortion legislation in 1976 and later when the law on abortion on women's request came into force in January 1979, the number of induced abortions per 1000 women 15-44 years of age has decreased by 20%, until December 31, 1983. For no age group has the number of induced abortions per 1000 women increased since the liberalization of the abortion legislation. While the number of terminations of pregnancy per 1000 women below the age of 25 has remained unchanged since 1975, the number of abortions per 1000 women aged 25-29 has decreased by nearly 18% and for women aged 30-44, by 34%. The number of terminated pregnancies per 1000 women of fertile age has shown a decrease corresponding to the reduction in births per 1000 women. Thus the liberalization of the abortion law cannot account for the decreased number of births after 1975.     

Cerebral palsy births in eastern Denmark, 1987--90: implications for neonatal care

The Cerebral Palsy Register in eastern Denmark has collected cases using a uniform data sampling procedure since birth year 1979. We have investigated changes in the rate of cerebral palsy, related to gestational age, mortality and perinatal risk factors in children born 1983--90. The total cerebral palsy birth prevalence decreased from 3.0 in the birth year period 1983--86 to 2.4 per 1000 live births (P < 0.01) in 1987--90, owing to a decrease among all preterm infants (29--19 per 1000, P < 0.001). The perinatal and early neonatal mortality in preterm infants was unchanged from 1983--86 to 1987--90. The rate of cerebral palsy in term infants was 1.5 per 1000 in all birth-year periods from 1979--90. Among the cerebral palsy infants, the proportion of very preterm babies treated with mechanical ventilation in the neonatal period decreased from 95% in 1983--86 to 61% in 1987--90 (P < 0.001), while the group treated with CPAP among the moderately preterm babies increased from 61% to 78% (P < 0.05). The significant decline in cerebral palsy rate in preterm infants born 1987--90 may be due to a change in treatment at the neonatal intensive care units using less mechanical ventilation, a hypothesis which needs further investigation.     

Socioeconomic status and risk of infant death. A population-based study of trends in Norway, 1967-1998

BACKGROUND: The aim of this study was to examine the association between socioeconomic status and risk of infant death in Norway from 1967 to 1998. METHODS: Information from the Medical Birth Registry of Norway on all live births and infant deaths was linked to information from Statistics Norway on parents' education. There were 1777364 eligible live births and 15517 infant deaths. Differences between education groups were estimated as risk differences, relative risks, population attributable fractions, and index of inequality ratios. RESULTS: The risk of infant death decreased in all education groups, and the level of education increased over time. The trends differed for neonatal and postneonatal death. For neonatal death the risk difference between infants whose mothers had high and low education was reduced from 3.5/1000 in the 1970s to 0.9/1000 in the 1990s. The relative index of inequality (RII) for maternal education decreased from 1.72 to1.32. The proportion of neonatal deaths that could be attributed to <13 years of education decreased from 22.3 to 8.4. For postneonatal death the risk difference between infants whose mothers had high and low education increased from 0.7/1000 in the 1970s to 2.0/1000 in the 1990s. The RII for maternal education increased from 1.31 to 4.00. The population attributable fraction increased from 9.7 to 39.5. CONCLUSIONS: An inverse association between socioeconomic status and risk of postneonatal death persists, albeit there was a considerable reduction in risk between 1967 and 1998.     

Northern Territory indigenous life expectancy improvements, 1967-2004

OBJECTIVE: To assess the extent of changes in life expectancy at birth for the Indigenous population of the Northern Territory (NT) over the period 1967-2004, and to determine which age-specific mortality rates were mostly responsible for such change. METHODS: Life expectancy at birth figures were obtained via life table calculations using a high-quality and internally consistent dataset of NT Indigenous deaths and populations covering the period 1967-2004. A life expectancy at birth age decomposition technique was then applied. RESULTS: Indigenous life expectancy at birth has risen considerably in the NT, increasing from about 52 years for males and 54 years females in the late 1960s to about 60 years for males and 68 years for females in recent years. Significantly, for NT Indigenous females the gap with total Australian life expectancy has narrowed. CONCLUSIONS: In contrast to popular perception, Indigenous life expectancy in the Northern Territory has improved substantially from the late 1960s to the present. IMPLICATIONS: The widespread pessimism that surrounds Indigenous health and mortality is largely unfounded, at least for the NT. Although much remains to be done to reduce Indigenous mortality, the results in this paper demonstrate that improvements are occurring and that sustained and increased effort is worthwhile and will succeed.     

Secular Trends in Uncertain-Sex Births and Proportion of Male Births in Norway, 1967-1998

It has been hypothesized that environmental factors influence sex differentiation in the fetus, thus causing a reduced sex ratio (male/female) at birth, an increase in the prevalence of ambiguous-sex infants, and possibly an increase in spontaneous abortion rates. In Norway, subsequent to 1967, all deliveries, including late abortions after 16 wk of gestation, have been reported to the Medical Birth Registry of Norway. The authors used these data to assess birth-weight-specific secular trends of uncertain-sex infants and the proportion of male births, from 1967 through 1998. Total rates of uncertain-sex infants increased from 2.3/10,000 births in 1967 to 8.0/10,000 births in 1998 in the birth weight strata of less than 600 gm. The total proportion of male births was stable; however, there was a reduction in the proportion of male births among births weighing less than 400 gm—from 58.4% to 53.4%. Incomplete ascertainment of abortions may have biased the results, but it would not have accounted for the increased occurrence of uncertain-sex infants and the decreased proportion of males observed among late-term abortions.     

A controlled field trial of plain and aluminium hydroxide-adsorbed cholera vaccines in Surabaya, Indonesia, during 1973--75.

A controlled field trial comparing the effectiveness of a plain cholera vaccine with that of a vaccine adsorbed to aluminium hydroxide was carried out in a cholera-endemic area of Indonesia during 1973-75. Tetanus toxoid adsorbed to aluminium phosphate was used as the control. In vaccinees aged 1-4 years, the adsorbed cholera vaccine provided about 88% protection for 6 months following vaccination and still provided about 50% protection between 11 and 14 months after vaccination. In the same age group, the plain vaccine provided only 53% protection during the first 6 months and no appreciable protection beyond that period. In those aged 5 years and over, both vaccines provided 50-60% protection throughout the period of observation (14 months). Neither vaccine caused any serious side effects.     

Perinatal mortality in single and multiple births in Japan, 1980–1991

Summary. Perinatal mortality rates (PMR) decreased significantly per year in single, twin, triplet, quadruplet and quintuplet births during the period 1980–1991. The PMRs were 7.7 per 1000 livebirths for singletons, 45.6 for twins, 89.0 for triplets, 116.8 for quadruplets, and 476.2 for quintuplets during the 12 years. The relative risks of perinatal death in multiplets vs. singletons were 6 for twins, 12 for triplets, 15 for quadruplets and 62 for quintuplets. The PMR was significantly higher in males than females for singletons and twins, but there was no sex differential in PMRs for higher order of multiple births. The PMR increased with birth order in twins and triplets, whereas there was no birth order effect on the PMR for quadruplets. An increasing proportion of multiple births among perinatal deaths may be related to the increasing multiple birth rate in Japan.     

National independence,women's political participation,and life expectancy in Norway

This study investigates the role of national independence and women's political participation on population health using historical lifespan data from Norway. We use time-series methods to analyze data measuring the actual length of time lived by Norwegian birth cohorts spanning a 61 year period surrounding the political emancipation of Norway from Sweden in 1905 and the establishment of a Norwegian monarchy in 1906. The use of a discrete, historical event improves our ability to interpret the population health effects of national independence and women's political participation as causal. We find a large and significant positive effect on the lifespan of Norwegian females born in the 1906 cohort. Interestingly, the effect does not extend to all living females during the Norwegian drive toward sovereignty. We conclude that the beneficial effects were likely conferred through intrauterine biological transfers and/or neonatal investments specific to the first year of life.     

Induced abortions and births. Changes in maternal age and parity in six counties, Norway, 1972-1981

During the 1970s the abortion law changed twice in Norway. As of 1976 induced abortion was accepted on social indications, while abortion on womens' demand was introduced in 1979. This study presents age-specific abortion- and birth rates as well as age- and parity-specific abortion ratio from 1972-1981. From 1972 to 1974 the number of induced abortions increased. Since then the general abortion rate has decreased. For all parity groups the number of pregnancies terminated by induced abortion increased during the first 3 years of the study. While nulliparous women showed a continuous increase in the abortion ratio throughout the study period, the abortion ratio for parous women has been relatively stable since 1975. Through the use of induced abortion nulliparous mothers postpone the birth of their first child. Therefore induced abortion contributes to an increasing maternal age at first child birth. The present study can support the hypothesis that multiparous women, among other means, have used induced abortion to establish the 2-child family norm during the 1970s.     

A population-based study of cancer incidence in twins and in children with congenital malformations or low birth weight, Norway, 1967-1980

The incidence of childhood cancer in twins, in children with congenital malformations diagnosed at birth, and in children of low birth weight was investigated and compared with that in the total population of Norway born live from 1967-1979. Only the malformation group had a significantly increased rate of total cancer (28.3/100,000 person-years) compared with the population (14.6/100,000). The excess cancer appeared to be limited to children with Down's syndrome or a central nervous system defect, who most frequently developed leukemia or central nervous system tumors, respectively. The rates of total cancer in children of low birth weight (9.3/100,000) and in twins (13.0/100,000) were close to expected. However, twins had a significantly increased rate of renal cancer (rate ratio = 4.1). The documented associations between cancers and congenital malformations are suggestive of some common etiologic factors which warrant further studies for their identification and for elucidating possible means of prevention.     

Sudden infant death syndrome during weekends and holidays in Norway in 1967-1985

A few previous studies have revealed an increased risk for sudden infant death syndrome (SIDS) during weekends and holidays suggesting environmental factors as potential trigger mechanisms for death. In the present study, the weekend/holiday effect has been assessed on the basis of 1480 SIDS cases in 19 Norwegian counties during a 19-year period (1967-85). The phenomenon has been confirmed for 17 of the 19 counties. Special attention has been attached to differences in the geographical and seasonal distribution of the phenomenon. Deaths of other causes in infancy did not display such a dependency on the day of the week.     

基于南通市人口数据的Elandt-Johnson模型法完全寿命表推算研究

目的 探索Elandt-Johnson模型法推算完全寿命表的效果。方法 以南通市2020年1月1日至12月31日年龄别死亡率为实例构建简略寿命表和实际完全寿命表,采用Elandt-Johnson模型将简略寿命表推算成完全寿命表,将推算的完全寿命表死亡率、尚存人数等指标与实际完全寿命表进行拟合,并比较推算完全寿命表和实际完全寿命表的期望寿命。 结果 采用Elandt-Johnson模型推算的年龄别死亡率、尚存人数与实际年龄别死亡率、尚存人数拟合度较好,决定系数分别为0.9328、0.9050,由推算的尚存人数计算的期望寿命(83.03岁)与实际期望寿命(83.23岁)非常接近。结论 Elandt-Johnson模型可以将简略寿命表推算出较准确的完全寿命表,可用于南通市完全寿命表的推算。