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PubMed2005

Factors affecting duration of the expulsive stage of parturition and piglet birth intervals in sows with uncomplicated, spontaneous farrowings.

Modern pig farming is still confronted with high perinatal piglet losses which are mainly contributed to factors associated with the progress of piglet expulsion. Therefore the aim of this study was to identify sow- and piglet factors affecting the duration of the expulsive stage of farrowing and piglet birth intervals in spontaneous farrowing sows originating from five different breeds. In total 211 litters were investigated. Breed affected duration of the expulsive stage significantly: the shortest duration was found in Large White x Meishan F2 crossbred litters and the longest duration in Dutch Landrace litters. No effect of parity on the duration of the expulsive stage was found. An increase in littersize (P<0.01), an increase in number of stillborn piglets per litter (P<0.05) and a decrease of gestation length (P<0.05, independently of littersize) all resulted in an increased duration of the expulsive stage of farrowing. A curvilinear relationship between birth interval and rank (relative position in the birth order) of the piglets was found. Besides that, piglet birth intervals increased with an increasing birth weight (P<0.001). Stillborn (P<0.01) and posteriorly presented (P<0.05) piglets were delivered after significantly longer birth intervals than liveborn and anteriorly presented piglets. The results on sow- and piglet factors affecting duration of the expulsive stage and piglet birth intervals obtained in this study contribute to an increased insight into (patho) physiological aspects of perinatal mortality in pigs.

Animals↗
PubMed1993

Determinants of birth intervals in Vietnam: a hazard model analysis.

There was absence of any regional differences in parity progressions and length of birth intervals, although urban-rural differences persisted at most birth orders, suggesting that, as in other studies, the urban-rural differentials are the primary source of variations in fertility between different areas of a country. The significantly higher probability of a subsequent birth after birth order 2 in areas with high infant mortality compared to those with low infant mortality suggests that women in the high-risk provinces may be more likely to advance beyond parity 2 and continue on into the advanced parities. The provinces identified as having high infant mortality had also been identified in other studies as the provinces with the highest crude birth rates and population growth rates, the least available family planning services, and highest crude death rates. Mothers' education was consistently related to the likelihood of another birth at each birth order, with the most-educated women experiencing a significantly lower probability of having a subsequent birth at every birth order. This concurs with results in other studies, suggesting that the woman's education is a prime determinant of fertility and that increasing the educational attainment of women is one of the most beneficial measures to reduce fertility. The significant relationship between the previous birth interval of the index child and the probability that the index child would be followed by a subsequent birth conforms with other studies of birth interval dynamics that suggest that pregnancy-spacing for a given woman remains constant throughout her reproductive career.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Determinants of birth intervals in Kerala: an application of Cox's hazard model.

"The present study is an attempt to delineate the differences in the patterns and determinants of birth intervals which appear highly relevant in a transitional population such as Kerala [India]. In this country two comparable surveys, with a period difference of 20 years, were conducted. The study tries to estimate the effects of socio-economic, demographic and proximate variables using Cox's proportional hazard model. For the former data-set, socio-economic variables have [a] significant effect on birth intervals, while for the latter data proximate variables are the significant determinants of birth intervals." (SUMMARY IN ITA AND FRE)

Asia↗
PubMed1993

Estimation of fecundity and secondary sterility from survey data on birth intervals in Egypt.

Data on the last closed and open birth intervals have been used to ascertain the current potential of childbearing for women in terms of estimating fecundity and secondary sterility by age, residence, and educational subgroup. Under the assumption that after a specific period from the last birth a certain proportion of women become secondarily sterile, we propose and apply an inflated model of open birth interval to obtain the proportion of women who are secondarily sterile. The data used for the analysis are extracted from the Egyptian Fertility Survey conducted in 1980.

Adolescent↗
PubMed2006

Risk factors for preeclampsia in multiparous women: primipaternity versus the birth interval hypothesis.

INTRODUCTION: To determine whether the risk of preeclampsia in multiparous women with a previous normal pregnancy is related to changing paternity or to prolonged birth interval, a retrospective study was conducted at the Lyell McEwin Health Service (University of Adelaide). METHODS: The study included all multiparous women known to the hospital because of their preceding 1st delivery in the same hospital followed by their 2nd and/or 3rd ongoing pregnancy resulting in a delivery in the period 2001 - 2003. Case records were analyzed for birth interval, pregnancy interval, paternity and recognized risk factors such as booking weight and smoking. For the analysis both the International Society for the Study of Hypertension in Pregnancy (ISSHP) definition and the more recently introduced classification by the Australian Society for the Study of Hypertension in Pregnancy (ASSHP) were used. RESULTS: In the 656 women in this study cohort, 148 (26.2%) women had a different partner in their 2nd and/or 3rd ongoing pregnancy. Using the ISSHP definition for preeclampsia, changing partners had an odds ratio (OR) of 1.304 (95% CI 0.43 - 3.99); using ASSHP criteria an OR of 1.556 (95% CI 0.6506 - 3721); and looking at the combined group of pregnancy-induced hypertensive disorders an OR of 1.99 (95% CI 1.01 - 3.89). A longer birth interval if anything was associated with a lower risk of preeclampsia (non-significant), whatever definition was used. Also the inter-pregnancy interval did not show a consistent relation with the risk for developing a hypertensive complication. CONCLUSIONS: The results of this study on risk factors for preeclampsia in multiparous women appear to be in line with the primipaternity hypothesis, but are in direct contrast with the so-called birth interval hypothesis.

Adult↗
PubMedDate not supplied

Fecundity of daughters born after short, intermediate, or long birth intervals. An analysis of family reconstitutions from The Netherlands, late 19th-early 20th century.

In an historical cohort study, we compared the reproductive performances of women born after short (< 14 completed months), intermediate (21-32 completed months), and long (> 39 completed months) birth intervals. Of the initial study base, comprising family reconstitutions of 1,425 women born between 1873 and 1902 in or around Rotterdam (The Netherlands) and married before age 45, a large portion (data of 1,001 women born between 1888 and 1902) was uninformative because of (unintended) selection on birth control behavior. Among the remaining 424 women, those born after very short birth intervals (less than 1 year) showed higher likelihood of childlessness and stillbirth in the offspring than those born after intermediate intervals (adjusted odds ratios (OR) and 95%-confidence intervals: 7.7 [1.8-33.0] and 3.3 [1.3-8.3], respectively). The latter association, however, nearly disappeared after restriction to women whose preceding sibling lived at least 1 year. Women born after modestly short intervals (12-13 months) exhibited longer interpregnancy intervals. So did women born after long birth intervals, but this might well be attributable to intergenerational transmission of reproductive behavior. These results indicate that fecundability is reduced in women born after short birth intervals.

Adult↗
PubMed1989

To what extent does breastfeeding explain birth-interval effects on early childhood mortality?

This article shows that in Nepal breastfeeding almost completely explains the effects of following birth interval on childhood mortality during the first 18 months of age and partially explains the effect of following birth interval on childhood mortality between 18 and 60 months of age. Breastfeeding does not explain the effect of preceding birth interval on childhood mortality. The analysis is based on application of hazard models to data from the 1976 Nepal Fertility Survey.

Birth Intervals↗
PubMed1993

Influence of birth interval and child labour on family energy requirements and dependency ratios in two traditional subsistence economies in Africa.

The consequences of different birth intervals on dietary energy requirements and dependency ratios at different stages of the family lifecycle are modelled for Gambian agriculturalists and !Kung hunter-gatherers. Energy requirements reach a peak at between 20 and 30 years after starting a family for the Gambians, and between 15 and 20 years for the !Kung. For the Gambians, shorter birth interval confers no economic advantage over the traditional birth interval of 30 months. For the !Kung, the lack of participation in subsistence activities by children gives an output:input ratio in excess of that reported in other studies, suggesting that they are in a state of chronic energy deficiency.

Adolescent↗
PubMed1983

On a modification of life table technique for analysis of birth interval data and its application.

"This paper presents some modifications [of] the usual life table technique to analyse the data on the time of first birth and inter live birth intervals which are compiled from the birth histories of females, of varying marital durations, enumerated in a retrospective survey." The fact that a female may not be exposed to the risk of conception following childbirth or marriage, because of postpartum amenorrhea or of customs involving visits to parents, is taken into account. A method to obtain maximum likelihood estimates of the conditional risk of conception is given, and an analysis of birth intervals is presented using this technique and data for India from the Rural Development and Population Growth--A Sample Survey 1978.

Amenorrhea↗
PubMed2000

Social-demographic influence on first birth interval in China, 1980-1992.

This study examines the delay between first marriage and first live birth in China among a sample of women who married between 1980 and 1992. Most couples in China only use contraception after the first child is born. Most sample women had their first child within 2 years of marriage. However, there are significant rural-urban differences in the first birth interval, indicating that there was most probably deliberate fertility regulation after marriage among many urban couples. Survival analysis shows that place of residence, level of education, age at first marriage and marriage cohort affect the first birth interval.

Adolescent↗
PubMedDate not supplied

Breastfeeding, contraception, and birth intervals in developing countries.

Numerous studies have demonstrated a strong correlation between breastfeeding and the duration of amenorrhea and between breastfeeding and the birth interval at the individual level. In the present study, both these correlations are shown to hold at the national level, in developing countries. In countries where the median durations of breastfeeding are relatively long or the rates of contraceptive use are relatively high, median birth intervals are longer than in countries where the median breastfeeding durations are shorter and contraceptive use is less widespread. In countries where fertility is moderate or high, however, the incidence of very short birth intervals is higher when median breastfeeding durations are relatively short. The findings suggest that contraception as it is presently practiced is an inadequate substitute for breastfeeding.

Birth Intervals↗
PubMed1983

A modified stochastic model for closed birth interval.

"Based on some simple assumptions regarding [the] human reproduction process, a continuous time stochastic model for describing the variation in any closed birth interval of a woman of marital duration (t) has been developed. The model incorporates the possibility of the variation of the amenorrhea period among the women under observation. For illustration, the model is applied to an observed closed birth interval between first and second births of the women with marital duration of seven years."

Birth Intervals↗
PubMed1990

Application of a stochastic model to ascertain the truncation bias and systematic component of variation in closed birth interval.

"In this paper an attempt is made to estimate the truncation bias in the mean length of closed birth interval caused by the termination of observations after [a] certain time, through the application of a stochastic model based on certain simplified assumptions. The approach is further evolved to determine the relative contributions of...chance and systematic components to the variance of closed birth interval when the fecundability parameter follows a priori distribution. Some numerical results have also been presented for the purpose of illustration."

Bias↗
PubMed1989

Effect of delivery season on subsequent birth interval in early 20th century in Japan.

Questionnaires of birth dates of family members (13,404 families in total) were analyzed in order to examine the effects of delivery season of a baby on the subsequent birth interval. Deliveries at maternal age of 20-34 years were used. In 1921-1935, the mothers who had been delivered of a baby in August-October showed the shortest (30.62 months geometric mean) and those in February-April the longest (34.05 months) non-last intervals, with a highly significant difference among the four delivery seasons (P less than 0.001, Kruskal-Wallis test, n = 5678). Although the intervals were abruptly prolonged just before the last birth, the above difference was also consistent in the last intervals. When seasonal distributions of last and non-last births were compared, last births tended to be concentrated in the summer half of a year (P less than 0.05) in 1921-1935. In 1951-1965, overall geometric mean of the interval shortened to 28.44 months, and the length of intervals did not differ appreciably according to the season of preceding delivery. Deliveries in late summer (August-October) in 1921-1935, therefore, were associated with increased risk of termination of reproduction, on one hand, but a lowered chance of prolongation of the subsequent interval, on the other hand. Possible environmental factors are discussed to explain this apparently paradoxical phenomenon.

Adult↗
PubMed1986

On a probability distribution to study the open birth interval and its application.

"A probability distribution for describing the variation in the length of open birth interval regardless of parity has been derived assuming that fecundability varies from female to female and the births are of two types, one which results [in] infant death and the other [which does] not. To get the estimates of the parameters, expressions for the first two moments have been derived. The model has been applied to the data taken from the survey 'Rural Development and Population Growth--A Sample Survey 1978,' conducted under the auspices of the Demographic Research Centre, Banaras Hindu University [India]."

Asia↗
PubMed1999

Effects of the status of women on the first-birth interval in Indian urban society.

The status of women, which is relative and multidimensional, has an important bearing on any long-term reduction in fertility. In Indian society, where cohabitation and childbearing are socially sanctioned only after marriage, the length of the first-birth interval affects the completed family size by influencing the spacing and childbearing pattern of a family. This study examines the influence of certain aspects of the status of married women--education, employment, role in family decision making, and age at marriage--along with three socioeconomic variables--per capita income of the family, social position of the household, and the caste system--on the duration of the first-birth interval in an urban Hindu society of the north-east Indian state of Assam. The data were analysed by applying life table and hazard regression techniques. The results indicate that a female's age at marriage, education, current age, role in decision making, and the per capita income of the household are the main covariates that strongly influence the length of the first-birth interval of Hindu females of urban Assam. Of all the covariates studied, a female's education appears to be a key mediating factor, through its influence on her probability of employment outside the home and thereby an earned income and on her role in family decision making. Unlike other Indian communities, the effect of the caste system does not have a significant effect on first-birth timing in this urban Hindu society.

Adolescent↗
PubMed1999

Birth intervals, breastfeeding and determinants of childhood mortality in Malawi.

Childhood mortality in Malawi is analyzed by employing proportional hazards models. The analysis uses highly reliable data collected from the 1992 Demographic and Health Survey (DHS) of Malawi. The results show that the substantial birth interval and maternal age effects are largely limited to the infant period. The influence of social and economic variables on the mortality risk and on the relationship between biodemographic variables and mortality risk is much enhanced with increasing age of the child. It has also been found that consideration of breastfeeding status of the child does not significantly alter interpretation of effects of preceding birth interval length on mortality risk, but does partially diminish the succeeding birth interval effect. The results are discussed and then summarized in the context of policy implications for Malawi. The paper addresses a very important issue in Malawi and it adds valuable insights to the base of knowledge in childhood mortality in sub-Sahara Africa.

Adolescent↗