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At least 19 recordsLinked to original sources
PubMed1979

Seasonal migration and seasonal variation in fecundability: effects on birth rates and birth intervals.

Seasonal patterns in conception rates have been documented in several recent studies. In this paper, a mathematical model of the reproductive process is developed through which the impact of such variation in conception rates is assessed. It is found that the effect on fertility can be quite substantial, but that the birth rate when seasonal variation is occurring is approximated well by the birth rate calculated when conception rates are constant at their mean. These results indicate that further documentation of seasonality in conception rates and exploration of the causes of these patterns and their change is an important area for demographic research.

Birth Rate↗
PubMed1976

[Family formation by schizophrenic and manic-depressive patients according to an epidemiologic study (birth rate)].

The birth rate among patients with endogenous disorders is considered as an index of the degree of their social adaptation. It was established that in all forms of such disorders the level of birth rates and the rate of family formation is lower than that in the general population. However, in all endogenous disorders (except the malignant schizophrenia) there are some patients the adaptation of whom is not disturbed.

Adolescent↗
PubMed1992

[Analysis of factors influencing the recent decline in birth rate in Tokyo].

This study was undertaken in an attempt to find factors which affected the recent declining birth rate in Tokyo. Vital statistics of the female population, age 20-39, for the period of 1970 through 1985 for Tokyo were compared to national averages. Indices examined were birth rate, percentage of married women, birth rate for married women, and birth rate for married women by live birth order. Results thus obtained were as follows: 1. Birth rates for females aged 20-24 and 25-29 were largely dependent on percentages of married women rather than birth rates for married women both in Tokyo and in the nation as a whole, while the birth rates for females aged 30-34 and 35-39 were more dependent on birth rates for married women. 2. Percentages of married women aged 20-24 and 25-29 decreased during the observation period both in Tokyo and in the nation as a whole. 3. Birth rates for married women aged 30-34 and 35-39 dropped in the first 5 or 10 years of observation in both groups as a result of the reduction in high order live births. Thereafter, the decline changed to an upturn trend. 4. Yearly changes of birth rate, percentage of married women, birth rate for married women, birth rate for married women by live birth order, and birth rate of first child for married women appeared to have the same timing both in Tokyo and in Japan as a whole in each age category.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
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↗
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↗
PubMed1992

Socioeconomic factors affecting first marriage and birth rates by sex and age in the total Japanese population.

The effects of a wide variety of social, economic and demographic factors on age-specific first marriage and live birth rates in 46 Japanese prefectures were analyzed using stepwise regression analysis for 1970 and again for 1975 after classification of those twenty-two factors by factor analysis. The principal results were as follows: (1) high employment (high income) and social mobility caused by industrialization had a strongly positive influence on the first marriage and birth rates for young females, (2) rural and urban residence factors had positive effects on the marriage and birth rates for young males and females, respectively, (3) old age factor had an inverse effect on the marriage rates for both males and females over a wide range of ages, and (4) young age factor promoted the birth rate for young and middle-aged females. The characteristics of the first marriage and live birth rates in Japan were discussed in the light of these findings.

Adolescent↗
PubMed1979

The mortality and birth rates of spina bifida during a period of treatment, selection and antenatal screening in Sheffield, 1963-1978.

The birth rates for all neural tube defects and the mortality rates from spina bifida and encephalocele have been obtained for Sheffield children by examining the congenital anomalies register and death certificates during the period from 1963-1978. The introduction of atenatal alpha foetoprotein screening of all pregnant women in 1977 is associated in time with a sharp fall in the birth rate of neural tube defects. The mortality rate for spina bifida with encephalocele rose gradually from 1967 to 1976, apparently unaffected by the introduction of clinical selection prior to surgery in 1971. The antenatal screening of previously affected families (since 1973) did not affect the mortality rate, but screening the total pregnant population since 1977 has been associated with a sharp reduction in the mortality rate. The mortality rate curve for spina bifida with encephalocele is markedly different from the birth rate curve which makes the common practice of inferring birth rates from mortality rates invalid. There was a gradual increase from 1967 to 1978 in the proportion of children born with spina bifida in any given year who died before their second birthday. This increase appears to have been uninfluenced by the introduction of selection or antenatal screening. The changes in mortality rate and survival may be as much due to unknown factors as to changes in medical management.

Amniotic Fluid↗
PubMed1979

Analysis of multiple birth rates in Japan. 1. Secular trend, maternal age effect, and geographical variation in twinning rates.

Mean twin, triplet, and quadruplet birth rates in Japan from 1951 to 1968 were 6.41, 0.056, and 0.00094 per 1,000, respectively. In 1974 the corresponding figures were 5.83, 0.059, and 0.00329. No quintuplets were born in the former period, but a set was born in the latter year, the rate being 0.47 per million. From 1955 to 1966 the MZ twinning rate increased slightly, but decreased thereafter. This increase was limited to live-born MZ twins, particularly in the higher maternal age groups. The DZ twinning rate declined in the entire period, particularly in higher maternal age groups. This decline appeared to be essentially limited to fetal deaths. Among live births the MZ twinning rate underwent a nearly linear increase with maternal age, whereas the DZ twinning rate attained a mode in the maternal age group 35--39 years. The MZ and the DZ twinning rates among fetal deaths by maternal age had unimodal distributions with modes in maternal age groups 25--29 and 30--34 years, respectively. As to the DZ twinning rate, a geographical cline was noted, with a high rate in the northeast of Japan; the rate was positively correlated with latitude, which also positively correlated with the presence of multiple births among relatives. A negative but nonsignificant correlation was seen between the DZ twinning rate and the proportion of mothers treated with ovulation-inducing hormone. The proportion was higher in mothers of unlike-sexed twins than in those of like-sexed twins and in mothers of triplets than in those of twins. An association between DZ twinning rate and age-specific fertility per married woman is suggested to exist among higher maternal age groups in the northeast part of Japan in earlier years.

Adult↗
PubMed1992

Information dissemination and the cesarean birth rate. The Illinois experience.

A study was initiated to investigate the impact of information dissemination in Illinois upon the projected rise in the cesarean birth rate over the period from 1986 through 1988. The total cesarean birth rate in Illinois had not changed significantly during this period, whereas the rate of vaginal births after cesarean sections (VBAC) increased by 58.4% (p < .001). Information dissemination may have contributed to stemming an increase in the cesarean birth rate in Illinois while promoting VBAC deliveries.

Adolescent↗
PubMed1976

[Birth rate (1)].

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Birth Rate↗
PubMed1976

[Birth rate (2)].

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Birth Rate↗