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PubMed2000

Variations in teenage birth rates, 1991-98: national and state trends.

OBJECTIVES: This report presents national birth rates for teenagers for 1991-98 and the percent change, 1991-98. State-specific teenage birth rates by age, race, and Hispanic origin for 1991 and 1998 and the percent change, 1991 to 1998, are also presented. METHODS: Tabular and graphical descriptions of the trends in teenage birth rates for the Nation and each State, by age group, race, and Hispanic origin of the mother, are discussed. RESULTS: Birth rates for teenagers 15-19 years declined nationally between 1991 and 1998 for all age and race and Hispanic origin populations, with the steepest declines recorded for black teenagers. State-specific rates fell significantly in all States for ages 15-19 years; declines ranged from 10 to 38 percent. In general, rates by State fell more for younger than for older teenagers, ranging by State from 10 to 46 percent for ages 15-17 years. Statistically significant reductions for older teenagers ranged from 3 to 39 percent. Reductions by State were largest for black teenagers 15-19 years, with rates falling 30 percent or more in 15 States. Among the factors accounting for these declines are decreased sexual activity, increases in condom use, and the adoption of the implant and injectable contraceptives.

Adolescent↗
PubMed1987

The non-decline in U.S. twin birth rates, 1964-1983.

Detailed twin birth rates for the United States are unavailable since 1964. In 1983 the crude twinning rate for women of white race was higher than in 1964, but there had been great changes in maternal age and parity. Indirect standardization for maternal age and birth order provides estimated total twinning rates that can be compared over the entire period. The adjusted rates for whites show a nearly continuous increase except after a 2-year reporting hiatus, 1969-70, when rates dropped back 10%. In blacks the adjusted rate increased between 1966 and 1978, except for the 1968-71 shift. The distributions of rate increases by maternal age and by race argue against effects of medical ovulation stimulants, but a disproportionate increase of triplets argues for such effects. Study is needed of rates specific for maternal age and parity, rather than of total rates.

Birth Rate↗
PubMed2001

Ecological analysis of teen birth rates: association with community income and income inequality.

OBJECTIVES: To examine whether per capita income and income inequality are independently associated with teen birth rate in populous U.S. counties. METHODS: This study used 1990 U.S. Census data and National Center for Health Statistics birth data. Income inequality was measured with the 90:10 ratio, a ratio of percent of cumulative income held by the richest and poorest population deciles. Linear regression and analysis of variance were used to assess associations between county-level average income, income inequality, and teen birth rates among counties with population greater than 100,000. RESULTS: Among teens aged 15-17, income inequality and per capita income were independently associated with birth rate; the mean birth rate was 54 per 1,000 in counties with low income and high income inequality, and 19 per 1,000 in counties with high income and low inequality. Among older teens (aged 18-19) only per capita income was significantly associated with birth rate. CONCLUSIONS: Although teen childbearing is the result of individual behaviors, these findings suggest that community-level factors such as income and income inequality may contribute significantly to differences in teen birth rates.

Adolescent↗
PubMed1988

[[Analysis of multiple birth rates in Japan]].

The author analyzes multiple birth rates in Japan based on data from published vital statistics for the years 1951-1968 and from computer files for 1974-1985. "The higher multiple birth rate since 1974 was attributed to the higher proportion of mothers treated with ovulation-inducing hormones in Japan." (SUMMARY IN ENG)

Asia↗
PubMed2006

Sperm quality, birth rates and the environment in Flanders (Belgium).

The relationship between fertility and pollution is unclear. We evaluated sperm quality of 562 candidate donors (years 1977-2004), births rates (births), pollutants, and the number of females in reproductive age (NFRA, 20-39 years) in Flanders. Total sperm count did not change significantly with time. Births correlated with sperm morphology (r=0.60, P=0.0027). Continuing decline in sperm morphology with time is confirmed, statistically unrelated to pollutants. Grade A sperm motility declined (1977-1992) with gradual incomplete recovery thereafter. Multiple regression analysis (1995-2002) indicated dioxin (negative association) as the only independent variable for grade A motility (r-adjusted co-efficient of determination "r-adjusted"=0.76, P=0.008). Births and pollution were positively associated but births were only dependent on NFRA (r-adjusted=0.91, P<0.001). Our results suggest a relation between dioxin and sperm motility, partially reversible upon reduction of environmental dioxin. Though significantly correlated with sperm morphology, births are primarily associated with demographic factors.

Adult↗
PubMed1999

Declines in teenage birth rates, 1991-98: update of national and state trends.

OBJECTIVES: This report presents national birth rates for teenagers for 1991-98; the percent change, 1991-98; State-specific teenage birth rates for 1991 and 1997; and the percent change, 1991-97. METHODS: Tabular and graphical descriptions of the trends in teenage birth rates by age group, race, and Hispanic origin of the mother are discussed. RESULTS: Birth rates for teenagers 15-19 years declined nationally between 1991 and 1998 for all age, race, and Hispanic origin populations, with the steepest declines recorded for black women. State-specific rates by age fell in all States, with most declines statistically significant; overall declines ranged from 9 to 32 percent.

Adolescent↗
PubMed1998

Reliability of league tables of in vitro fertilisation clinics: retrospective analysis of live birth rates.

OBJECTIVE: To determine to what extent institutions carrying out in vitro fertilisation can reasonably be ranked according to their live birth rates. DESIGN: Retrospective analysis of prospectively collected data on live birth rate after in vitro fertilisation. SETTING: 52 clinics in the United Kingdom carrying out in vitro fertilisation over the period April 1994 to March 1995. MAIN OUTCOME MEASURE: Estimated adjusted live birth rate for each clinic; their rank and its associated uncertainty. RESULTS: There were substantial and significant differences between the live birth rates of the clinics. There was great uncertainty, however, concerning the true ranks, particularly for the smaller clinics. Only one clinic could be confidently ranked in the bottom quarter according to this measure of performance. Many centres had substantial changes in rank between years, even though their live birth rate did not change significantly. CONCLUSIONS: Even when there are substantial differences between institutions, ranks are extremely unreliable statistical summaries of performance and change in performance, particularly for smaller institutions. Any performance indicator should always be associated with a measure of sampling variability.

Birth Rate↗
PubMed1993

Nurses' care during labor: its effect on the cesarean birth rate of healthy, nulliparous women.

This retrospective study was designed to determine the influence of nurses' care during labor and delivery on the cesarean birth rate of healthy, nulliparous women. Labor and delivery nurses in a large, nonprofit hospital were grouped according to the cesarean birth rates of their healthy, nulliparous patients in spontaneous labor. Large differences in cesarean birth rates between nurses in the lowest quintile (near 4.9%) and the highest quintile (near 19%) were not explained by differences in maternal age and gravidity, attendance of mother at childbirth class, insurance status, reliance on public assistance, physician who attended labor, use of epidural anesthesia, augmentation of labor, dilation when the nurse assumed care, infant weight, or gestational age. In multivariate analysis, the elapsed time between when the nurse assumed care and birth was significantly shorter for patients of nurses in the lowest quintile of cesarean birth rate (4.4 hrs) compared with patients of nurses in the highest quintile (5.6 hrs). The former were also less likely to have forceps used to assist vaginal delivery than the latter (13% vs 26%). Nurses in the lowest quintile of cesarean birth rates were more likely to use a form to record psychosocial data than nurses in the highest quintile (35% vs 15%). The study suggests that nurses' care during labor is an important factor influencing cesarean birth rates.

Adult↗
PubMed2005

Birth rate and its correlation with the lunar cycle and specific atmospheric conditions.

OBJECTIVE: This study was undertaken to use the Arizona State birth certificate database for Phoenix metropolitan hospitals, in conjunction with National Weather Service records to determine whether there is a relationship between birth rate and meteorologic or lunar conditions. This study attempts to dispel or lend significance to beliefs among hospital staff that the phase of the moon and/or meteorologic conditions are related to birth rate. STUDY DESIGN: Birth records were limited to spontaneous vaginal deliveries, 37 to 40 weeks' gestation, in Phoenix, between 1995 and 2000 (n = 167,956). Daily birth counts were merged with daily surface weather statistics from the National Weather Service for Sky Harbor Airport, and records of lunar phase for the same period. RESULTS: The analyses revealed no significant correlates of birth rate. CONCLUSION: Although there exists a popular belief that the phase of the lunar cycle and weather conditions affect birth rate, no such evidence was found in this study.

Arizona↗
PubMed1975

Contraceptive practice required to meet a prescribed crude birth rate target: a proposed macro-model (TABRAP) and hypothetical illustrations.

TABRAP (TArget Birth Rate Acceptor Program) is a computer programmed model that provides a direct solution to the problem of determining the total annual numbers of contraceptive acceptors required to achieve a prescribed crude birth rate target path. Applied to an initial population for which age structure, the fertility schedule, and expected trends in life expectancy and age-specific proportions of females married are known, TABRAP incorporates the following factors: age at acceptance, with acceptors drawn from currently married nonusers; age-method-specific attrition rates of users; a potential fertility schedule of acceptors that allows for aging and sterility; and allowance both for postpartum anovulation and nine months for gestation to time properly the averted births. TABRAP generates annual data on acceptors, couple-years of use, births averted and age-specific fertility rates that meet the crude birth rate target. Resulting changes in population size, age structure and crude vital rates, also yielded, are invariant with respect to acceptor age and method mix. Assuming a target to reduce the crude birth rate from 45 to 30 in ten years, TABRAP is illustrated for seven mixes of acceptor age-method combinations applied to a population approximately that of Thailand, circa 1965.

Adolescent↗
PubMedDate not supplied

Reducing the preterm birth rate: a population health strategy.

The rate of preterm birth has been increasing in Canada and the United States. Efforts to prevent preterm birth have been largely ineffective. A population health strategy that integrates disease prevention and health promotion is needed. In this article, the five categories of health determinants proposed by the Federal, Provincial and Territorial Advisory Committee on Population Health are used as a framework to discuss risk factors and propose policies and interventions to reduce the preterm birth rate.

Canada↗
PubMedDate not supplied

The use of socioeconomic data to predict teenage birth rates. An exploratory study in Massachusetts.

In an exploratory study of adolescent fertility in 24 Massachusetts cities, age-specific birth rates constructed specifically for the study constituted the dependable variables. Data from the 1980 U.S. Census provided the independent socioeconomic variables for the analysis. The relationships between birth rates and these independent variables were explored through simple and partial correlation analyses. Results of the analyses confirm the assumption that rates of birth to teenagers vary systematically in relation to socioeconomic variables. They also confirm at the macro level the results of several earlier household survey showing an association between family income on the one hand, and adolescent sexual activity, contraception, and abortion on the other. In the current study, economic variables, particularly the median income of all families in the community, were found to be highly significant predictors of fertility among adolescents 15 to 19 years of age. The fertility of the generation to which the teenagers' mothers belonged (that is, women 35 to 44 years old) was also significantly associated with the teenagers' birth rates. The results for teenage mothers 15 through 17 years old and teenage mothers 18 and 19 years old were similar.

Adolescent↗
PubMedDate not supplied

Birth-rate re-appraisal in southern Africa.

The birth rate may not be slowing as fast as originally thought in Botswana and Zimbabwe, the two Sub-Saharan countries believed to be making the best progress towards curtailing population growth. A new study from the World Bank has re-examined the evidence on which the claims of fertility decline were based, and concluded that the figures may have been misinterpreted. Two censuses, carried out in 1984 and 1988, revealed a steep drop in the birth-rate. But the bank study shows that the two surveys are no longer compatible, because the later one questioned better-educated women. Women who have more schooling are more likely to be using contraceptives, regardless of the success or failure of a country's family planning program. This means that projections for the size of the two countries' populations have certainly been underestimated. "Among women aged 25 to 34 years in Zimbabwe in 1984, between 20% - 50% of the observed fertility-decline can be attributed to differences in education across the surveys; between 20% - 30% of the decline among women aged 35 to 44 years in Botswana can similarly be explained," the report says.

Africa↗
PubMed1998

Determinants of preterm birth rates in Canada from 1981 through 1983 and from 1992 through 1994.

BACKGROUND: The rates of preterm birth have increased in many countries, including Canada, over the past 20 years. However, the factors underlying the increase are poorly understood. METHODS: We used data from the Statistics Canada live-birth and stillbirth data bases to determine the effects of changes in the frequency of multiple births, registration of births occurring very early in gestation, patterns of obstetrical intervention, and use of ultrasonographic dating of gestational age on the rates of preterm birth in Canada from 1981 through 1983 and from 1992 through 1994. All births in 9 of the 12 provinces and territories of Canada were included. Logistic-regression analysis and Poisson regression analysis were used to estimate changes between the two three-year periods, after adjustment for the above-mentioned determinants of the likelihood of preterm births. RESULTS: Preterm births increased from 6.3 percent of live births in 1981 through 1983 to 6.8 percent in 1992 through 1994, a relative increase of 9 percent (95 percent confidence interval, 7 to 10 percent). Among singleton births, preterm births increased by 5 percent (95 percent confidence interval, 3 to 6 percent). Multiple births increased from 1.9 percent to 2.1 percent of all live births; the rates of preterm birth among live births resulting from multiple gestations increased by 25 percent (95 percent confidence interval, 21 to 28 percent). Adjustment for the determinants of the likelihood of preterm birth reduced the increase in the rate of preterm birth to 3 percent among all live births and 1 percent among singleton births. CONCLUSIONS: The recent increase in preterm births in Canada is largely attributable to changes in the frequency of multiple births, obstetrical intervention, and the use of ultrasound-based estimates of gestational age.

Birth Rate↗
PubMed1992

The role of selection bias in comparing cesarean birth rates between physician and midwifery management.

OBJECTIVE: The midwifery service at our hospital has been observed to have a 2% cesarean birth rate consistently over a 10-year period. There are substantial differences in labor management style between the midwives and physicians. We sought to test the hypothesis that the low cesarean birth rate on the midwifery service was the result of patient selection bias. METHODS: A randomized blinded clinical trial was conducted in which 492 low-risk patients were assigned to either physician or midwifery management. The provider responsible for labor management was unable to determine group assignment. Patients in the midwifery group were managed by previously established protocols, and outcome was attributed to the midwives even if the patients subsequently required transfer to physician management. Route of delivery was the primary outcome measurement. Continuous variables were analyzed using Student t test and discrete variables using chi 2. RESULTS: There were no demographic differences between the groups, and the admission pelvic examinations were the same. The patients assigned to the midwifery group had a 2.1% cesarean birth rate, whereas those assigned to physician management had a 0.4% rate. The higher rate of operative vaginal deliveries in the physician group was statistically significant. There were no differences in neonatal outcomes. The physician-managed group had significantly more episiotomies and third- and fourth-degree extensions. CONCLUSIONS: The 2% cesarean birth rate observed on the midwifery service appeared to be the result of patient selection bias. A low cesarean birth rate can be achieved by either physician or midwifery management in a selected low-risk population.

Adult↗
PubMed1999

Annual variation in birth rate of people who subsequently develop schizophrenia.

BACKGROUND: Previous attempts to decide whether there is significant year-to-year variation in the birth rate of people who subsequently develop schizophrenia have given conflicting results, probably because of differences in the statistical methods employed. AIMS: To determine whether there is significant year-to-year variation in the birth rate. METHOD: Variation in the birth rate for the period 1921-1960 was studied in three separate national data sets--English, Danish and Scottish--using cubic splines to smooth the distribution curve before calculating residuals from a Poisson distribution. RESULTS: Over-dispersion was found in all three data sets, particularly in the Danish and Scottish data. However, the correlation between the sets of standardised residuals derived from the three data sets was only statistically significant for Denmark v. England. CONCLUSIONS: There was statistically significant year-to-year variation in the birth rate of people who subsequently developed schizophrenia in three countries in north-west Europe in the years 1921-1960. This is potentially a clue to the nature of the environmental determinants of schizophrenia, but better data will be needed before useful explanatory hypotheses can be generated and tested.

Adult↗
PubMed2005

The singleton, term gestation, and live birth rate per cycle initiated: a 1-year experience in in vitro fertilization cycles with native and donated oocytes.

OBJECTIVE: To investigate the singleton, term gestation, and live birth rate per cycle initiated in our IVF program during a 1-year period. DESIGN: Retrospective study of all first IVF cycles performed in the year 2002, with or without intracytoplasmic sperm injection (ICSI), with day 2/3 embryo transfer and using native or donated oocytes. SETTING: Instituto Valenciano de Infetilidad (IVI), Valencia, Spain. PATIENT(S): Of 3,158 IVF cycles initially considered, 165 were excluded because of embryo freezing, follow-up loss, or embryo reduction. Of the remaining cycles, only 1,836 were first cycles with day 2/3 embryo transfer; of these, native oocytes were employed in 1,095 and donated oocytes in 741. INTERVENTION(S): No patient underwent any additional procedure or intervention. MAIN OUTCOME MEASURE(S): The singleton, term gestation, and live birth rate per cycle initiated was used as a primary outcome measure. Results were analyzed according to the origin of the oocytes (native vs. donated) and the woman's age (<37 and > or =37 years old). RESULT(S): The ectopic pregnancy rate was higher in the native oocyte group. The singleton, term gestation, and live birth rate per cycle initiated was similar in native and donated oocyte groups (15.3% vs. 13.4%). In the native oocyte group, patients <37 years old showed a significantly better outcome. The singleton, term gestation, and live birth rate per cycle initiated was 16.7% and 10.8% in younger and older women, respectively. CONCLUSION(S): The singleton, term gestation, and live birth rate per cycle initiated constitutes an essential parameter for determining the real possibility of a healthy baby for a specific assisted reproduction technology (ART).

Adult↗