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At least 19 recordsLinked to original sources
PubMed1984

Fetal mortality in oral cleft families (VII): Birth intervals.

Birth intervals in sibships of oral cleft probands are analysed to detect prolonged delays between successive pregnancies. Such intervals are useful indicators of undetected fetal mortality. The present study indicates that the average interval for 462 cleft families in Indiana is 30.61 months. The average interval leading to the birth of a cleft child is 33.94 and is significantly greater than the average interval for the entire sample. Although the contraception status of the Indiana population is not known, the significantly greater delay preceding the birth of a cleft child is indicative of a cause other than contraception. This finding is in agreement with the report by Drillien et al. (1966) that abnormal conceptions occur more frequently adjacent to cleft offspring. It is interesting that some increase in the average interval is also noted in the present study immediately following the birth of a cleft child. Such delays occurring both preceding and following the birth of a cleft child (in contrast to smaller intervals for other pregnancies in the same sibships) may indicate excessive fetal wastage due to a combination of genetic and environmental factors.

Birth Intervals↗
PubMed1996

[Birth intervals and birth of low weight infants in Benin].

Low birthweight is a public health problem in Benin but its etiology remains unclear. Studies in industrial countries suggest several risk factors including the interval between pregnancies or child spacing. The purpose of this cohort study was to assess the relationship between pregnancy interval and low birthweight in Benin. Data were collected from a total of 2,862 multiparous pregnant women randomly recruited in 1991 at the time of their first prenatal care visit to maternity units in Cotonou, Benin. Sociodemographic information and obstetrical history were obtained by interviewing the mother and reviewing delivery records. About 15% of the women recruited delivered low birthweight children. The relative risks of preterm birthweight and intrauterine growth retardation was calculated in function of three pregnancy intervals: less than 12 months, 12 to 23 months, and 24 to 34 months. It was 1.31 (1.00-1.75), 1.00 (0.70-1.02)) and 0.77 (0.60-0.87) respectively for preterm birthweight and 1.27 (1.03-1.64), 1.17 (0.79-1.39) and 0.79 5 (0.57-0.87) respectively for intrauterine growth retardation. Logistic regression analysis taking into account sociodemographic factors and previous obstetrical history did not show a significant correlation between pregnancy interval and preterm low birthweight or between pregnancy interval and intrauterine growth retardation. Maternal nutritional status, maternal age, number of previous births, and education level were correlated with low birthweight.

Adult↗
PubMed2005

Birth intervals and injectable contraception in sub-Saharan Africa.

OBJECTIVE: The interval between births is associated with child survival in the developing world. We aimed to investigate associations between use of depot-medroxyprogesterone acetate and other reversible contraception and short birth intervals in sub-Saharan Africa. METHODS: Data from successive Demographic and Health Surveys undertaken in nine African countries were analyzed. Logistic regression was used to explain changes in the proportion of short birth intervals in four countries with relatively high use of reversible contraception. FINDINGS: The overall odds ratio for the trend was 0.90 (95% CI 0.84 to 0.95) and this was unaffected by adjusting for the other variables. The odds of a short birth interval were reduced by exclusive breastfeeding (OR 0.67, 95% CI 0.58 to 0.78) and increased by use of injectable contraception (OR 1.23, 95% CI 1.11 to 1.38). CONCLUSION: The proportion of short birth intervals has changed little over the last decade in a context of very low use of the intrauterine device. Widespread adoption of injectable contraception is associated with greater odds of a short birth interval, thus not contributing favorable conditions for improved child health.

Adult↗
PubMed1993

Selected determinants of fertility in Vietnam: age at marriage, marriage to first birth interval and age at first birth.

Data from the 4172 women aged 15-49 interviewed in the 1988 Vietnamese Demographic and Health Survey were used to examine age at marriage, marriage to first birth intervals and age at first birth. Differences between urban and rural areas, northern and southern provinces and by education of the women were analysed. The majority of the women had their first birth before age 20, but women with secondary education had a significantly higher age at first birth than those with little or no education, and women from the north had a significantly higher age at first birth than women from the south. Rural women and those with little or no education married at significantly younger ages than urban women and those with secondary education; these education effects were confirmed in a rural subsample of women. Women from rural areas and from the north had significantly shorter marriage to first birth intervals than urban women and those from the south, but there were no significant effects related to education.

Adolescent↗
PubMed1999

The association of birth interval, maternal age and season of birth with the fertility of daughters: a retrospective cohort study based on family reconstitutions from nineteenth and early twentieth century Quebec.

In a historical follow-up study, we evaluated the association of the fertility of daughters with five perinatal factors: short (< 15 months) or long (> or = 45 months) preceding birth interval, low (< or = 20 years) or advanced (> or = 40 years) maternal age and season of birth. We used data concerning 2062 women married before the age of 31 and born in the Saguenay region of Quebec, Canada, between 1850 and 1899. Time between the wedding and first birth was used for the estimation of differences in fertility. Using logistic regression and controlling for several potential confounders, we found a slightly increased risk of monthly failure of conception for daughters born after a short but not for those born after a long birth interval (odds ratios [ORs] 1.09 [0.89, 1.33] and 0.87 [0.65, 1.16], respectively, with intervals between 21 and 32 months as the reference category). A slightly increased risk of conceptive failure was also seen for daughters of younger and older mothers (ORs 1.08 [0.89, 1.30] and 1.11 [0.91, 1.35], respectively, compared with maternal age between 24 and 30 years as the reference category). Fertility varied by season of birth (P = 0.02), with summer-born daughters having lowest and winter-born daughters having highest fertility. These results are consistent with the idea that maternal factors before or around birth play a role in the aetiology of reduced fertility. The data, however, do not unequivocally support the hypothesis that gave rise to the present study, namely that ovarian development may be disturbed after conception in conditions with an increased risk of maternal menstrual cycle irregularities.

Adolescent↗
PubMed2005

Do children born before and after adequate birth intervals do better at school?

There are un-verified reports that adequate birth intervals are associated with better physical and mental development children in the school age. The objective of this study was to investigate the effect of preceding and succeeding birth intervals on the school performance of 9-10-year-old male Saudi children. This is a cross-sectional study of the performance of Saudi school children in relation to the length of the birth interval before and after the birth of the index child, conducted in Khobar, Eastern Saudi Arabia. A two-stage randomized sampling technique was adopted. Data were collected on scholastic achievements. Data was analyzed using SPSS software using chi-square, linear and logistic regression analysis. Children born after birth intervals longer than 31 months who scored grade A in the year of study, and the year before, were found to be significantly more than children born after intervals less than 17 months. There are more above-average students amongst those born after an interval of 31 months or more compared to those born after a shorter birth interval of 17 months or less according to teachers. Significantly more children born before birth interval longer than 35 months did better at school than children born before interval shorter intervals (less than 19 months). Logistic regression analysis showed that the possibility of classifying the index child as average or above in school performance increased as the succeeding birth interval increased. Results of the study verified previous findings that children born after adequate birth intervals do better at school. The study revealed that the succeeding birth interval in relation to school performance is more significant than the preceding birth interval. Apart from mother's education and breastfeeding, no other variables were found to be significantly related to the birth interval. These findings would enable us to advise couples that by observing a birth interval of around 3 years, their children are likely to do better at school.

Birth Intervals↗
PubMedDate not supplied

Is the reduction of birth intervals an efficient reproductive strategy in traditional Morocco?

Birth interval lengths are analysed from reproductive life histories of 517 Berber peasant women of the region of Marrakesh (Southern Morocco), whose fertility developed in a full traditional context. The high mortality rates associated with short birth intervals indicate that a rapid succession of births is detrimental to the progeny. The reproductive efficiency of the traditional propensity to a large family size is therefore examined by means of two different evaluations of reproductive success: the 'absolute' reproductive success (the absolute number of offspring surviving to maturity) and the 'relative' reproductive success (the proportion of live born surviving to maturity). The first shows that close pregnancies increase the fertility rate to such an extent that the associate higher number of deaths is more than compensated for, so that the women practising short birth intervals produce more surviving offspring than the others by the end of their reproductive life. The second shows that the probability of survival is directly associated with birth interval length, the efficiency of the reproductive process being therefore greater as birth intervals grow. It is suggested that these two behaviours are not contradictory, and that they represent two successive steps of the same reproductive adjustment to evolving environmental conditions.

Aged↗
PubMed2006

The effects of birth interval on the birthweights of consecutive, same-sex term siblings.

OBJECTIVE: To investigate the effect of birth interval on the relationship between the birthweights of successive siblings. METHODS: The records of women who had delivered two consecutive, same-sex, live, singletons babies (1983 through 1997) in a private hospital were analysed. The intervals between the birth dates of the siblings were calculated. The first of the siblings was coded Set A and the second, Set B. The ratios of the birthweights (Set B/Set A) were calculated. Comparison of findings was made between various ranges of birth interval. RESULTS: The birth interval band 24-29 months was associated with the highest mean birthweight for Set B babies and the highest birthweight ratio (p=0.016). Set A babies weighing less than 3000 g were most likely to be outweighed by their Set B siblings (p=0.000001). CONCLUSION: Birth intervals of 24 to 29 months and small size of Set A babies were associated with most significant advantages in birthweight for Set B siblings.

Birth Intervals↗
PubMed1989

Determinants of birth intervals in Sudan.

Using individual birth history data from the Sudan Fertility Survey, 1979, parity-related differences in fertility are demonstrated, as well as differences between socioeconomic groups. Rural women, women with no education and those married to uneducated husbands show rapid parity progression and its cumulative effects on fertility which are consistent over all birth intervals. Urban women, women with some education and those married to educated husbands, however, go rapidly through their second and third birth intervals and then more slowly at higher parities. A limitation of the study was the inability to control fully for the effects of breast-feeding and contraception. There is evidence for a reduction in high parity births, starting in the 1970s.

Birth Intervals↗
PubMed1997

Birth interval and the sex of children in a traditional African population: an evolutionary analysis.

Birth interval is a major determinant of rates of fertility, and is also a measure of parental investment in a child. In this paper the length of the birth interval in a traditional African population is analysed by sex of children. Birth intervals after the birth of a boy were significantly longer than after the birth of a girl, indicating higher parental investment in boys. However, in women of high parity, this differential disappeared. Birth intervals for women with no son were shorter than for those with at least one son. All these results are compatible with an evolutionary analysis of reproductive decision-making. First born sons have particularly high reproductive success, daughters have average reproductive success and late born sons have low reproductive success. The birth interval follows a similar trend, suggesting that longer birth intervals represent higher maternal investment in children of high reproductive potential.

Adult↗
PubMed2004

Parturition in gilts: duration of farrowing, birth intervals and placenta expulsion in relation to maternal, piglet and placental traits.

Large White x Meishan F2 crossbred gilts (n = 57) were observed continuously during farrowing while the placentae of their offspring were labeled in order to examine the duration of farrowing and placenta expulsion in relation to maternal-, piglet- and placental traits and the duration of birth interval in relation to birth weight, birth order and placental traits. Independently from each other, litter size, gestation length and offspring directed aggression significantly (P 0.05) affected duration of farrowing. An increase in litter size was associated with an increase of duration of farrowing and an increase in gestation length was associated with a decrease of duration of farrowing. Aggressive gilts took longer to farrow, compared to non-aggressive ones. After taking into account litter size, gestation length and offspring directed aggression, placental thickness (i.e., placental weight corrected for placental surface area) was significantly (P < 0.05) related to duration of farrowing, i.e., litters with on average thicker placentae took longer to farrow. The latter effect is the result of the fact that individual placental thickness significantly (P < 0.01) affected individual birth interval, independent of birth weight. The piglet has to break its own membranes to be able to start its journey through the uterus towards the birth channel. Apparently, a thicker placenta offers more resistance and thus prolongs the process of birth. Independent of placental thickness, birth interval significantly (P < 0.01) decreased with an increase in birth order (first born to last born). The high variation of birth intervals for the last born piglets, caused a slight increase in average birth interval for the latter piglets. Litters with on average more areolae per placenta took significantly (P < 0.001) less time to be born than litters with on average less areolae per placenta (independent of total number of piglets born and other placental traits), while birth intervals within litters were not affected by this trait. Thus, these results are probably due to a gilt trait rather than a piglet trait. Since the number of areolae represent the number of uterine glands present, the gilt trait might be uterine development. Duration of placenta expulsion significantly (P < 0.01) increased with an increase of duration of farrowing. Furthermore, the first placenta was expelled significantly (P < 0.01) earlier relative to last piglet when duration of farrowing was protracted, while there was no relation of the time interval between first placenta and last piglet and the duration of placenta expulsion. In conclusion, the most important finding of this study is that placental thickness rather than birth weight appears to play an important role in the duration of birth intervals and as a result, of duration of parturition in gilts.

Aggression↗
PubMed2002

Birth order, birth interval, and deviant sexual preferences among sex offenders.

We investigated whether birth order and birth interval are associated with phallometric responding among 168 sex offenders. Based on the immunoreactivity hypothesis, we predicted that a larger number of older brothers and a shorter birth interval between the offenders and their next older brothers would be associated with more deviant responding. Results showed that a larger number of older brothers (but not older sisters, younger brothers, or younger sisters) was associated with more deviant responding on the Most Deviant Index, a general measure of sexual deviance. A larger number of older brothers was associated with arousal to nonsexual violence against women and children, but contrary to expectation, the same association was also found for the number of younger brothers. A short birth interval with the next older brother was associated with greater relative arousal to nonsexual violence, but the correlation with the Most Deviant Index did not reach statistical significance. Overall, results were consistent with the main predictions, but the effects of birth order and birth interval were mostly restricted to arousal to nonsexual violence. Birth order and birth interval were not associated with pedophilic interests or gender preferences.

Adult↗
PubMedDate not supplied

On a probability model of open birth interval.

"Many authors [have] pointed out that analysis of open birth interval (the period elapsed from the last live birth till the date of the survey) could be of great interest to study the process of human reproduction, because it directly exhibits changes in fertility due to recent use of contraception or incidence of secondary sterility. Moreover, open birth intervals may be chosen to study the linkage between fertility and migration. A probability model for describing variations in the length of open birth intervals has been applied separately to couples with both spouses present at home, and to couples with one spouse having migrated away. The model has then been applied to [survey data for India] to get an estimate of the risk of conception and of secondary sterility." (SUMMARY IN ITA AND FRE)

Asia↗
PubMedDate not supplied

Preceding birth intervals and child survival: searching for pathways of influence.

The importance of the length of preceding birth intervals for the survival chances of young children has been established, but the debate concerning the causal biomedical or behavioral mechanisms continues. This article uses data from 17 Demographic and Health Surveys to investigate the effect of birth intervals on child mortality: Anthropometry of children, recent morbidity of children, and use of health services are examined in addition to child survival data for children born in the five years before the survey. Various methodological approaches are used to investigate the relative importance of the postulated mechanisms linking birth intervals and child survival. Short preceding birth intervals are associated with increased mortality risks in the neonatal period and at 1-6 months of age, and, to a much lesser extent, at 7-23 months of age. The effects of short birth intervals on nutritional status are rather moderate, and there is a weak relationship with lower attendance at prenatal care services. No consistent relationship exists between the length of birth intervals and other health status or health-service utilization variables. The results indicate that prenatal mechanisms are more important than postnatal factors, such as sibling competition, in explaining the causal nature of the birth interval effect.

Anthropometry↗
PubMed2005

The effects of birth interval on intellectual development of Saudi school children in Eastern Saudi Arabia.

OBJECTIVE: The primary aim of this study was to investigate the effect of birth intervals on some aspects of intellectual ability of Saudi primary school boys. METHODS: This is a cross-sectional study of Saudi school children comparing their intellectual ability (general intelligence) in relation to the length of the birth interval before and after the birth of the index child. The study area comprised 3 townships in the eastern province; Khobar, Thogba and Dhahran. The study was conducted in 2000/2001 and the study population comprised Saudi primary school boys aged 9-10 years from a middle class background. A 2 stage random sampling technique was adopted. Data were collected using student data sheet, a family questionnaire and the Standard Progressive Raven Matrices Test of intellectual ability, standardized for use in Saudi Arabia. Data were analyzed using SPSS software. RESULTS: More than 90% of children born after a birth interval greater than 35 months were classified as average and above according to the Raven Matrices Test, compared to 79% of children born after a birth interval of less than 19 months (p<0.03). Analysis of variance showed that test scores increased consistently as the succeeding birth interval increased. Multivariate analysis showed the most import predicting variables in the Raven Matrices Test to be family income and height. CONCLUSION: Longer birth intervals were shown to be associated with higher general intelligence levels in the 9-10 year olds. These results confirm those obtained in a previous study in Singapore conducted more than 2 decades ago. Our results have also shown that the succeeding birth interval is more significant than the preceding interval in relation to perceptive ability of children. The findings enable us to advise parents that by observing a birth interval between 2-3 years would make their children grow and do better at school.

Analysis of Variance↗