Cytogenetic results of amniocentesis materials: incidence of abnormal karyotypes in the Turkish collaborative study

The experience on prenatal chromosome diagnosis of four Turkish centers participating in a collaborative study on 6041 genetic amniocentesis performed during a 4-8 years period were reviewed. 5887 (97.5%) patients had strong clinical indications for prenatal chromosome studies and 154 (2.5%) were referred because of maternal anxiety and a bad history of previous gestations. The main indication groups were: advanced maternal age (3197 cases), positive serum screening (2011 cases), ultrasound-identified anomaly (492 cases), previous fetus/child with chromosomal aberrations (103 cases), a history of a previous abnormal and/or mentally handicapped child (70 cases) and a parental chromosome rearrangement (14 cases). The average maternal age was 33.9 years and average gestational age was 18 weeks. A total of 179 affected fetuses were detected in this collaborative study (3%) of which 133 were unbalanced (74.3%). Among the 124 (69%) numerical aberrations, 102 (82.3%) were autosomal aneuploidies, 20 (16.1%) were gonosomal aneuploidies and 2 (1.6%) were poliploidies. Among the 55 (31%) structural aberrations, balanced translocation was the most common (63.6%) and 11 cases of inversion, four cases of unbalanced translocation, two cases of marker chromosome and three cases of other abnormalities were found. The overall culture success rate was 99.7%. Pregnancy termination that is permitted by legal authorities was accepted by 94.7% (126/133) with parents at unbalanced cytogenetic result announcement.     

Changes in maternal age distribution and their possible impact on demand for prenatal diagnostic services

Between 1977 and 1985 there was a 65% increase in births to women aged 35 or more in England and Wales, but only a 15% increase in all births. Two factors of roughly equal importance were responsible for this differential increase. Firstly, the proportion of older women (35-44) among all women of reproductive age (15-44) increased from 28% in 1977 to 31% in 1985; and, secondly, in the same period the fertility rate for women aged 35-39 increased from 18·2 to 24·1 per 1000 and for women aged 40-44 from 4·1 to 4·6 per 1000.The increased fertility rate among older women is not due to an extension of the reproductive period but to a delay in childbearing. This delay was seen in women married only once and also in those who had remarried.As prenatal diagnosis for the exclusion of chromosome abnormalities is customarily offered to older mothers the increased numbers of women aged 35 or more and their increased fertility rate have important implications for the provision of obstetric and laboratory services. There were 51 859 live births to women aged 35 and over in 1985; the projected figure for 2001 is 85 000. If the use of prenatal diagnosis continues to increase facilities for about 70 000 prenatal cytogenetic analyses will be needed in 2001.     

Trends in event rate and case fatality of patients hospitalized with myocardial infarction between 1984 and 2001

Between 1984 and 1993, prevalence and case fatality of hospitalized acute myocardial infarction (AMI) had declined in the population of Halifax County. We aimed to determine whether these trends continued into the 21st century by investigating patient characteristics, treatment methods, and fatality for hospital admissions of residents of Halifax County, aged 25-74, during 1984-1989 (period 1), 1990-1993 (period 2), and 1998-2001 (period 3) and diagnosed as AMI that were extracted from databases for the Halifax County MONICA and ICONS (Improving Cardiovascular Outcomes in Nova Scotia) Studies. Trends in patient characteristics and treatment methods were assessed by chi2 statistics. Their association with 28-day fatality was determined by logistic regression. Event rate declined during 1984-1993 but not into 1998-2001 (p = 0.206). Compared with 1990-1993, fewer AMI patients during 1998-2001 were > or = 55 years (73.3% vs. 69.9%), cigarette smokers (49.8% vs. 42.9%), had a history of myocardial infarction (28.9% vs. 24.9%), and had an admission heart rate >100 (34.8% vs. 17.4%). Additionally, more patients had a history of diabetes (22.5% vs. 28.1%). Case fatality declined progressively over the 3 study time periods (16.6%, 13.1%, and 9.4%, respectively). Changes also occurred in prevalence of Killip class 4 status during admission (20.2%, 10.3%, and 13.3%, respectively), use of thrombolysis (9.0%, 30.9, and 32.6%, respectively), and percutaneous coronary intervention (PCI) (4.3%, 11.2%, and 22.4%, respectively) in the different periods. Significant associations were found between case fatality and patient history of diabetes, history of MI, age, elevated admission heart rate, Killip class 4 impairment, thrombolysis, and PCI. The ICONS registry of hospitalized acute myocardial infarctions was used to compare case fatality during 1998-2001 with that reported by the Halifax County MONICA Project for 1984-1993. Whereas the population rate of myocardial infarctions had declined between 1984-1993 but not subsequently, case fatality declined significantly throughout the study period. The continued decline in case fatality is likely explained by changes in patient profile on presentation and medical therapies, including the increased use of thrombolysis and PCI.     

Fetal and placenta chromosome constitution in 237 pregnancy losses

The aim of the study was to carry out cytogenetic analyses in pregnancy losses. Samples of cartilage and placenta tissue were obtained prospectively from 237 pregnancy losses of more than 16 weeks of gestation (130 stillbirths, 97 induced abortions and 10 early neonatal deaths). Cartilage culture was performed in 222 samples and placental culture was initiated in 224. The overall culture success rate was 83.5%, 72.3% in stillbirths, 97% in induced abortions and 100% in early neonatal death. An abnormal karyotype was detected in 52 cases: 6.9% in stillbirths, 43.6% in induced abortions and 20% in early neonatal deaths. The rate of discrepancy between the prenatal cytogenetic results in amniotic fluid and the post-termination karyotype was 3%. The tissue of choice for cytogenetic analysis was cartilage in induced abortions and early neonatal death, and placenta in stillbirth. The majority of cases had a chromosome abnormality: multiple congenital anomalies in 74.6%, and a single major anomaly in 9.7%.     

Evaluation of prenatal diagnosis of cleft lip/palate by foetal ultrasonographic examination

Ultrasound scans in the midtrimester of pregnancy are now a routine part of antenatal care in many countries. This type of screening procedure can detect serious foetal anomalies. Thanks to our registry of congenital anomalies a study was undertaken. The objective of the study was to evaluate prenatal detection of cleft lip (palate)(CL/P) by routine ultrasonographic examination of the foetus in 265679 consecutive pregnancies from 1979 to 1998. The percentage of prenatal detection of CL/P was low. For isolated malformation (foetuses with only CL/P) the detection rate was low: 17.8%; however, this detection rate increased from 5.3% during the period 1979-1988 to 26.5% during the period 1989-1998, for foetuses with associated malformations (foetuses with CL/P and one or more additional major malformations) these detection rates were 34.6, 13. 3 and 50.0%, respectively. In foetuses with associated malformations with CL/P this detection rate was higher for chromosomal abnormalities with CL/P and for non-syndromic, non-chromosomal multiply malformed children with CL/P than for non-chromosomal recognized syndromes with CL/P.     

Use of prenatal diagnostic procedures in pregnancies affected with birth defects, Hawaii, 1986-2002

BACKGROUND: Information on the utilization of prenatal ultrasound (US), amniocentesis (AC), and chorionic villus sampling (CVS) in pregnancies affected by birth defects in the United States is limited. The intent of this study was to report on the utilization of these procedures in Hawaii. METHODS: Cases were all infants and fetuses of any pregnancy outcome with birth defects, included in a Hawaii birth defects registry, and delivered during 1986-2002. The rates of prenatal US, AC/CVS, and prenatal diagnosis were calculated. RESULTS: Prenatal US was performed in 76% of the cases and AC/CVS in 14% of the cases. Prenatal diagnosis of a birth defect was made in 16% of the cases. The prenatal US, AC/CVS, and prenatal diagnosis rates in 1998-2002 were 1.5, 1.5, and 1.7 times the rates in 1986-1991, respectively. Among all birth defects, the AC/CVS rate for women aged <35 years was 7% and for women aged > or =35 years was 48%. Among chromosomal abnormalities, the AC/CVS rate for women aged <35 years was 36% and for women aged > or =35 years was 66%. CONCLUSIONS: Only a fraction of the Hawaii birth defects cases was prenatally diagnosed. The rates for prenatal US, AC/CVS, and prenatal diagnosis among pregnancies affected by birth defects were higher in 1998-2002 than in 1986-1991. AC/CVS rates were lower for maternal age <35 years.     

Evaluation and evolution during time of prenatal diagnosis of congenital heart diseases by routine fetal ultrasonographic examination

The objectives of this study were to evaluate routine prenatal diagnosis of congenital heart diseases (CHD) by fetal ultrasound examination in a well-defined population during the period 1994-1999 and to compare these results with the results from 1979 to 1993. This study included 80,076 consecutive pregnancies of known outcome from 1994 to 1999. CHD were classified as isolated or associated when at least one other major extra-cardiac malformation was present. Only 137 out of 688 malformed fetuses with CHD without chromosomal anomalies were detected (19.9%). The sensitivity of detection varied from 61.9% for malformations such as isolated hypoplastic left heart and single ventricle, to around 7-19% for atrial and ventricular septal defects. Prenatal detection rate of CHD was 11.4% for isolated cases, and 40.2% for multiple malformed with CHD. The gestational age at discovery varied from 16 to 36 weeks. There is no upper limit for termination of pregnancies in our country; 12.3% of all pregnancies were terminated after prenatal diagnosis. However, 62% of the pregnancies with a CHD detected prenatally were terminated. The detection rate of CHD increased during time from 9.2% during the period 1979-1988 to 13.7% during the period 1990-1993 and to 19.1% during the period 1994-1999. Our study shows large variation in the prenatal detection rate of CHD. Prenatal diagnosis of CHD is significantly higher when associated malformations are present. Cardiac defects affecting the size of the ventricles have the highest detection rate. Gestational age at discovery was 20-24 weeks for the majority of associated cardiac defects. The prenatal detection rate of CHD increased during time from 1979 to 1999.     

Detection and characterization of new genetic mutations in individuals heterozygous for lactate dehydrogenase-B(H) deficiency using DNA conformation polymorphism analysis and silver staining

In northwest European countries maternal age is increasing. This will lead to an increase of the prevalence of Down syndrome conceptuses. Meanwhile, the increased use of prenatal cytogenetic diagnosis (PCD) will lead to a decrease in the prevalence of Down syndrome among livebirths. We were interested to know what the result of these two opposite developments would be in the near future, and we describe here a model to quantify these processes and the resulting livebirth prevalence of Down syndrome. The model is demonstrated for The Netherlands from 1992 to 2001. The predicted livebirth prevalence for The Netherlands in 1992 is 1.36 per 1000. Demographic factors will cause an increase to 1.76 per 1000 in 2001 with present indications for PCD and a utilization ratio of 50%. An increase of the utilization ratio to 90% in 2001 will lead to a prevalence of 1.22 per 1000, a little less than the present prevalence. Alternative screening programs, including maternal serum screening, could lead to a further decrease of the livebirth prevalence. The model described here can be used for evaluation of the consequences of alternative forms of Down syndrome screening.     

Dynamics of Streptococcos pneumoniae antibiotic resistance extension in Moscow in 1998-2003]

During the 6-year observation period from 1998 to 2003 in Moscow there was recorded in 2000-2001 a decrease in the emergence of Streptococcos pneumoniae resistance to many antibacterials, while during the following years the respective index increased. The above dynamics in the resistance emergence was likely due to a decrease in the use of antibiotics in 1998-1999. In 2003 the rate of resistance to penicillin was 18.6%, 0.4 and 2.1% of the isolates were resistant to amoxicillin and cefotaxime respectively, the rate of resistance to erythromycin reached 19%, 65.4% of the resistant strains showed M phenotype. High rates of resistance were as well observed with respect to tetracycline (40.1%), co-trimoxazole (29.1%) and chloramphenicol (18.6%). Resistance to levofloxacin and moxifloxacin was detected only in rare strains.     

Prenatal diagnosis of trisomy 21: registration results from a single genetic center

This is a retrospective review of all collected amniotic fluid samples, chorionic villus samples and other fluid-aspirations (hygroma colli fluid/urine from megacystis) over an 11-year period (1996-2006) in a single Genetic Center (University Hospital Gasthuisberg, Leuven), looking at the prenatal diagnosis of trisomy 21. In this study a total of 404 diagnoses of trisomy 21 were made on 29696 samples (1.4%). The prenatal diagnosis of trisomy 21 increased over the years with 0.88% (21/2363) in 1996 and 1.99% (50/2512)in 2006. Also the type of invasive testing changed over the years with an increase of the proportion of trisomy 21- diagnoses by chorionic villussampling from 2001. Looking at the registry for perinatal activities in Flanders for the year 2006 the live birth incidence for trisomy 21 was 1/1782 and this is lower than the often reported incidence oftrisomy 21 at birth of 1/800: it is likely that the use of more sensitive screening methods for the prenatal detection of trisomy 21 and the election of termination for most affected pregnancies affects the birth incidence oftrisomy 21.     

Age-related effects on breeding phenology and success of Common Guillemots Uria aalge at a North Sea colony

Capsule: Common Guillemots Uria aalge show delayed breeding and marked age-related changes in reproductive success consistent with improved performance with experience.

Aims: To determine age of first breeding and age-related effects on breeding phenology and success of Common Guillemots.

Methods: Resighting data from a long-term colour-ringing study of Common Guillemot chicks were combined with observations of breeding phenology and success to follow the recruitment process, breeding phenology and success of 62 birds at a major North Sea colony over a 30-year period.

Results: The median age of first breeding of Common Guillemots was 6.6 years. There were no detectable costs of first breeding on return rates or the likelihood of breeding the next season but first time breeders bred later and less successfully. Age of first breeding and lifetime breeding success both varied among individuals but there was no clear optimal age of first breeding and early first breeding was not associated with higher lifetime breeding success.

Conclusions: Common Guillemots in the Isle of May population delayed breeding for 3–4 years beyond physiological maturity. The marked increase in breeding success with age was consistent with improved performance with experience rather than selection for higher quality individuals. Findings from this study will inform population models by providing improved estimates of age of first breeding and age-related changes in reproductive performance.     

Scientific publications of Costa Rica in Science Citation Index bibliometric analysis of the period 1999-2001

This study analyzed the publications of authors from Costa Rican institutions that were included in the Science Citation Index (SCI) during 1999-2001. Out of the 722 references detected, distributed in 328 journals, 90.7% corresponded to original research articles. The total productivity figures showed a moderately increasing trend, both in absolute and population-adjusted terms, in concordance with previous data recorded for the period 1980-1998. The contribution of Revista de Biología Tropical to these figures corresponded to 10.0%, 8.9%, and 19.1%, for the years 1999, 2000, and 2001, respectively. The subject distribution of articles followed a similar pattern to that described for 1980-1998, with a predominance of biomedical (33.3%) and biological (27.5%) sciences, followed by agronomical (15.5%) sciences, chemistry (13.6%), physics (5.0%), geological sciences (3.6%), and mathematics (1.5%). Citation analyses for individual publications (up to July 15, 2002) revealed that only 45.2% of the articles had been cited at least once. The ten most cited references were analyzed, varying from 26 to 114 citations. The average citation per article was 2.60, and the average number of authors per article was 2.92. In agreement with data from 1980-1998, the University of Costa Rica appeared as the institution with highest productivity of SCI publications during 1999-2001, with a contribution of 50.0%. The percentage of publications performed without the participation of foreign co-authors showed a change in its decreasing trend of 1980-1998, stabilizing near the range of 25-30% during the period 1999-2001.     

Fire and dynamics of granivory on a California grassland forb

This study examines the effects of burning and granivory on the reproductive success of the rare plant Amsinckia grandiflora (Boraginaceae). Fire is often used in California grasslands as a means of exotic species control, but the indirect effects these controls have on the reproductive ecology of native plants are rarely assessed. The interaction of fire with granivory of A. grandiflora seeds was examined in California grasslands over five years (1998–2002). In 1998 and 1999, both burned and unburned plots had bird-exclusion (netted) and no-exclusion (open) treatments. Predation rates were high (51–99%) and final predation rates did not differ among treatments. In 2000, granivory rates in the unburned, open plots were lower than in previous years (14%), and rodent trapping yielded only a single animal. Low granivory rates were observed in 2001 for unburned, open plots (47%). In 2001, burned/open plots experienced significantly more granivory (87%) than either burned/netted plots (37%) or unburned/open plots (47%). In 2002, every seed was taken from burned, open plots. Granivory was highly variable, ranging from 4 to 100% per plot over a 3-week period. Nearly all plots were discovered (>10% predation) by granivores in all trials in all years. When data from all treatments were combined, significant differences in granivory rates occurred among years, indicating stronger inter-year effects than within-year effects due to burning or bird exclusion. Fire affects granivory when overall predation rates are low, but when predation levels are high (as they were in 1998 and 1999), fire may not affect granivory occurring within the same year. Models extending seed survivorship through the dry summer indicate that most seeds are eaten, even when granivory rates are low.     

Inequalities in mortality during and after restructuring of the New Zealand economy: repeated cohort studies

Objectives To determine whether disparities between income and mortality changed during a period of major structural and macroeconomic reform and to estimate the changing contribution of different diseases to these disparities.Design Repeated cohort studies.Data sources 1981, 1986, 1991, 1996, and 2001 censuses linked to mortality data.Population Total New Zealand population, ages 1-74 years.Methods Mortality rates standardised for age and ethnicity were calculated for each census cohort by level of household income. Standardised rate differences and rate ratios, and slope and relative indices of inequality (SII and RII), were calculated to measure disparities on both absolute and relative scales.Results All cause mortality rates declined over the 25 year study period in all groups stratified by sex, age, and income, except for 25-44 year olds of both sexes on low incomes among whom there was little change. In all age groups pooled, relative inequalities increased from 1981-4 to 1996-9 (RIIs increased from 1.85 (95% confidence interval 1.67 to 2.04) to 2.54 (2.29 to 2.82) for males and from 1.54 (1.35 to 1.76) to 2.12 (1.88 to 2.39) for females), then stabilised in 2001-4 (RIIs of 2.60 (2.34 to 2.89) and 2.18 (1.93 to 2.45), respectively). Absolute inequalities were stable over time, with a possible fall from 1996-9 to 2001-4. Cardiovascular disease was the major contributor to the observed disparities between income and mortality but decreased in importance from 45% in 1981-4 to 33% in 2001-4 for males and from 50% to 29% for females. The corresponding contribution of cancer increased from 16% to 22% for males and from 12% to 25% for females.Conclusions During and after restructuring of the economy disparities in mortality between income groups in New Zealand increased in relative terms (but not in absolute terms), but it is difficult to confidently draw a causal link with structural reforms. The contribution of different causes of death to this inequality changed over time, indicating a need to re-prioritise health policy accordingly.     

Prevalence of congenital anomalies at birth among offspring of women at risk for a genetic disorder and with a normal second-trimester ultrasound.

The goal of this study was to determine the prevalence and the nature of congenital anomalies found at birth in offspring of women who had a normal second-trimester ultrasound and/or amniocentesis. Two groups of women were studied in our prenatal diagnosis clinic between 1991-1997. Group 1 consisted of pregnant women who had an amniocentesis for advanced maternal age (AMA), or for familial chromosomal or monogenic disorders. Group 2 consisted of pregnant women attending the prenatal diagnosis clinic and who had no indication for amniocentesis. Those with an abnormal ultrasound and/or amniocentesis were excluded. At the time of delivery, a questionnaire was sent pertaining to perinatal complications and the anomalies detected during the neonatal period. From a total of 15, 370 questionnaires sent from 1991-1997, 10,823 (group 1, n = 8,877; group 2, n = 1,946) were returned (overall response rate, 70.4%). Mean maternal age was 36 years in group 1 and 29 years in group 2. The prevalence of perinatal complications was similar in the two groups. In each group, the prevalence of all unforeseen anomalies was 2.9%. In group 1, the distribution of those anomalies was: major anomalies, 67.7%; minor anomalies, 23.9%; and multiple congenital anomalies (MCA), 8.3%. In group 2, the distribution was: major anomalies, 70.7%; minor anomalies, 24.1%; and MCA, 5.2%. In patients at risk for a genetic disease and consulting in a prenatal diagnosis clinic, the prevalence of all anomalies diagnosed at birth was 2.9%, even if the second-trimester ultrasound and amniocentesis results were normal. Therefore, it is important to inform those couples of this remaining risk.     

Russian mortality trends for 1991-2001: analysis by cause and region

Objectives To investigate trends in Russian mortality for 1991-2001 with particular reference to trends since the Russian economic crisis in 1998 and to geographical differences within Russia.Design Analysis of data obtained from the Russian State statistics committee for 1991-2001. All cause mortality was compared between seven federal regions. Comparison of cause specific rates was conducted for young (15-34 years) and middle aged adults (35-69 years). The number of Russian adults who died before age 70 in the period 1992-2001 and whose deaths were attributable to increased mortality was calculated.Main outcome measures Age, sex, and cause specific mortality standardised to the world population.Results Mortality increased substantially after the economic crisis in 1998, with life expectancy falling to 58.9 years among men and 71.8 years among women by 2001. Most of these fluctuations were due to changes in mortality from vascular disease and violent deaths (mainly suicides, homicides, unintentional poisoning, and traffic incidents) among young and middle aged adults. Trends were similar in all parts of Russia. An extra 2.5-3 million Russian adults died in middle age in the period 1992-2001 than would have been expected based on 1991 mortality.Conclusions Russian mortality was already high in 1991 and has increased further in the subsequent decade. Fluctuations in mortality seem to correlate strongly with underlying economic and societal factors. On an individual level, alcohol consumption is strongly implicated in being at least partially responsible for many of these trends.     

Seasonal variation in reproductive measures of tropical Roseate Terns Sterna dougallih previously undescribed breeding patterns in a seabird

Seasonal variation in egg-laying, egg size, hatching success, hatchling mass, fledging success and chick growth of Roseate Terms Sterna dougallii breeding on Aride Island (Seychelles), Indian Ocean, were studied in 1997 and 1998. I investigated to what extent two patterns, common in a range of species, were followed by tropical Roseate Terns: (a) seasonal decrease in clutch size, egg size and breeding success and (b) an increase in breeding success with increasing egg weight. In 1997 (a poor year), the earliest nesting birds laid significantly smaller eggs, and chicks were lighter at hatching than those of peak nesting birds. The mean clutch size, of 1.04 eggs, showed no seasonal variation and no 'b'-eggs hatched. In 1998 (a good year) the earliest nesting birds laid eggs of similar size and their chicks were of similar weight to those of peak nesting birds. Mean clutch size, of 1.25 eggs, increased significantly through the season and about 60% of the 'b'-eggs hatched. In 1997, hatching success was 57% whereas in 1998 it was 80%. In both years, breeding success declined significantly through the season. The fact that the earliest breeding birds laid smaller eggs in a poor year and smaller clutches in a good year is in marked contrast to a range of other species, and to temperate-nesting Roseate Terns. Egg volume explained about half of the variance in hatchling mass in both years, but only 15% of the variation in linear growth rate. Hatching date was the only variable with a significant effect on fledging success. Roseate Terns on Aride seemed to sacrifice egg size and clutch size for earliness of laying. Presumably it is a strategy of older birds to lay as early as possible and may be regarded as a response of tropical Roseate Terns to breeding under relatively poor, and seasonally declining, food conditions.     

TRENDS IN ABUNDANCE OF ALASKA HARBOR SEALS, 1983–2001

We estimated trends in abundance of harbor seals ( Phoca vitulina richardsii ) using over dispersed, multinomial models and counts obtained during aerial surveys conducted during 1983–2001 in the Ketchikan, Sitka, Kodiak, and Bristol Bay areas of Alaska. Harbor seal numbers increased significantly at 7.4%/yr during 1983–1998 and 5.6%/yr during 1994–1998 in the Ketchikan area, and 6.6%/yr during 1993–2001 in the Kodiak area. Counts were stable (trends not significant) during 1984–2001 (0.7%/yr) and 1995–2001 (-0.4%/yr) in Sitka, and during 1998–2001 (-1.3%/yr) in Bristol Bay. The influence of covariates ( e.g. , survey date, tide height) on trend estimates was significant and varied among areas and across years, demonstrating the need to include covariates in statistical analyses to accurately estimate trend. Our increasing trend estimate for Kodiak represents the first documented increase in harbor seal numbers over a relatively expansive area in the Gulf of Alaska. However, the trend for the Gulf of Alaska stock is equivocal due to the continued decline in Prince William Sound. Similarly, the trend for the Southeast Alaska stock is equivocal based on our increasing (Ketchikan) and stable (Sitka) trend estimates, and a recent decline reported for Glacier Bay. The Bering Sea stock appears stable after a period of possible decline.     

Perinatal mortality in triplet births in Japan: time trends and factors influencing mortality.

Perinatal mortality rates (PMRs) in triplets were analyzed using Japanese Vital Statistics during the period of 1980-1998. The total number of perinatal deaths in triplets was 1051. The PMR significantly decreased from 214 per 1000 births in 1980 to 39 in 1998, a reduction of 82%. PMRs in triplets were 11.1-fold higher in 1980 and 6.9-fold higher in 1998 than in singletons, indicating that PMRs improved more in triplets than in singletons during the last two decades in Japan. The PMR was the highest in the third-born, followed by the second- and the first-born triplets in each period. As for maternal age, the PMR was 1.5-3.7 times higher in the < 25 years of age group than the other age groups. Additionally, the PMR was the lowest for birthweight (BW) >or= 2000 g during the entire period. In addition, the PMR decreased with gestational age (GA) of up to 38-39 weeks and increased thereafter. The effects of BW on the PMR were stronger than the effects of GA. The proportion of perinatal deaths in triplets with extremely low BW (< 1000 g) was 74% in 1980-1989 and increased to 82% in 1990-1998. The declining PMR was unlikely to be due to the improvement in BW in triplets. It is likely that it was related to the improved medical management of triplets during the perinatal period and the first week of life. Information obtained in the present study may be useful in counseling pregnant woman about triplet births.     

Epidemiological trends in multiple births in the United States, 1971-1998.

The astounding rise in multiple births in the United States continues. We analyzed live birth files from the U.S. National Center for Health Statistics. Twin, triplet, quadruplet, and quintuplet+ rates were calculated for the period 1971-1977 and for each year between 1990 and 1998. Triplet rates were also computed within categories of mother's education and age. The twin rate increased from 1.8% in 1971-77 to 2.8% in 1998. The rate of triplets increased 5.9-fold, quadruplets 11.9-fold, and quintuplets+ 5.3-fold between 1971-77 and 1998. Increases in triplet rates were much more marked among births to university-educated women and women 30 years and older. Among women 45 years and older, the triplet rate was approximately fifty times higher in 1998 than in 1971-77. This group of older women (> or = 45 years) had the highest multiple birth rate in 1998.