Effect of the interval between pregnancies on perinatal outcomes.
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BACKGROUND: A short interval between pregnancies has been associated with adverse perinatal outcomes. Whether that association is due to confounding by other risk factors, such as maternal age, socioeconomic status, and reproductive history, is unknown. METHODS: We evaluated the interpregnancy interval in relation to low birth weight, preterm birth, and small size for gestational age by analyzing data from the birth certificates of 173,205 singleton infants born alive to multiparous mothers in Utah from 1989 to 1996. RESULTS: Infants conceived 18 to 23 months after a previous live birth had the lowest risks of adverse perinatal outcomes; shorter and longer interpregnancy intervals were associated with higher risks. These associations persisted when the data were stratified according to and controlled for 16 biologic, sociodemographic, and behavioral risk factors. As compared with infants conceived 18 to 23 months after a live birth, infants conceived less than 6 months after a live birth had odds ratios of 1.4 (95 percent confidence interval, 1.3 to 1.6) for low birth weight, 1.4 (95 percent confidence interval, 1.3 to 1.5) for preterm birth, and 1.3 (95 percent confidence interval, 1.2 to 1.4) for small size for gestational age; infants conceived 120 months or more after a live birth had odds ratios of 2.0 (95 percent confidence interval, 1.7 to 2.4);1.5 (95 percent confidence interval, 1.3 to 1.7), and 1.8 (95 percent confidence interval, 1.6 to 2.0) for these three adverse outcomes, respectively, when we controlled for all 16 risk factors with logistic regression. CONCLUSIONS: The optimal interpregnancy interval for preventing adverse perinatal outcomes is 18 to 23 months. (+info)
The determinants of infant and child mortality in Tanzania.
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This paper investigates the determinants of infant and child mortality in Tanzania using the 1991/92 Tanzania Demographic and Health Survey. A hazards model is used to assess the relative effect of the variables hypothesized to influence under-five mortality. Short birth intervals, teenage pregnancies and previous child deaths are associated with increased risk of death. The Government of the United Republic of Tanzania should therefore maintain its commitment to encouraging women to space their births at least two years apart and delay childbearing beyond the teenage years. Further, this study shows that there is a remarkable lack of infant and child mortality differentials by socioeconomic subgroups of the population, which may reflect post-independence health policy and development strategies. Whilst lack of socioeconomic differentials can be considered an achievement of government policies, mortality remains high so there is still a long way to go before Tanzania achieves its stated goal of 'Health for All'. (+info)
Patterns of infection and day care utilization and risk of childhood acute lymphoblastic leukaemia.
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To investigate if decreased exposure to common childhood infections is associated with risk of childhood acute lymphoblastic leukaemia (ALL) we conducted a case-control study of 1842 newly diagnosed and immunophenotypically defined cases of ALL under age 15, and 1986 matched controls in the US. Data regarding day care, sibship size and common childhood infections were obtained through parental interviews. Data were analysed stratified by leukaemia lineage and separately for 'common' childhood ALL (age 2-5 years, CD19, CD10-positive). Neither attendance at day care nor time at day care was associated with risk of ALL overall or 'common' ALL. Ear infections during infancy were less common among cases, with odds ratios of 0.86, 0.83, 0.71 and 0.69 for 1, 2-4, 5+ episodes, and continuous infections respectively (trend P = 0.026). No effect of sibship size or birth interval was seen. With one exception (ear infections), these data do not support the hypothesis that a decrease in the occurrence of common childhood infection increases risk of ALL. (+info)
Postneonatal and child mortality among twins in Southern and Eastern Africa.
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BACKGROUND: Few studies have evaluated the difference in mortality between twins and singleton children during the postneonatal and childhood period in sub-Saharan Africa. The aim of this study was to quantify the excess mortality of twins during the postneonatal and childhood period and to identify factors that contribute to the excess mortality among twins. The different use made of health care services was hypothesized to contribute to the increased mortality. METHODS: The Demographic and Health Survey data on Malawi, Tanzania and Zambia were pooled. Logistic regression was used to estimate twin/singleton differences for the combined postneonatal and child mortality and to study the role of intermediate factors and effect modifiers. RESULTS: The study was based on 18 214 singleton children and 706 twins. The twin/ singleton odds ratio (OR) of the combined postneonatal and child mortality was 2.33 (95% CI : 1.85-2.93). This excess mortality was largest during the first year of life. Control for intermediate factors (preventive health care and breastfeeding) did not sizeably diminish the mortality difference. Effect modifiers that were associated with increased twin/singleton OR were male sex, unwanted child, short birth interval and low socioeconomic status. CONCLUSIONS: The excess mortality of twins compared to singletons is considerable. A difference in use of preventive health care or in breastfeeding cannot explain the increased mortality. Males, unwanted children, those born after a short birth interval and the socioeconomically disadvantaged are at special risk. The generally good attendance at under-5 clinics gives health care providers the opportunity for increased surveillance of these high-risk groups. (+info)
Effect of an older sibling and birth interval on the risk of childhood injury.
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OBJECTIVE: Certain family structures have been identified as putting children at high risk for injury. To further define children at highest risk, we set out to explore the effect of an older sibling and birth interval on the risk of injury related hospital admission or death. METHODS: Data were analyzed using a case-control design. Cases and controls were identified by linking longitudinal birth data from Washington state (1989-96) to death certificate records and hospital discharge data obtained from the Washington State Comprehensive Hospital Abstract Reporting System and frequency matched in a 1:2 ratio on year of birth. Cases consisted of singleton children 6 years of age or younger who were hospitalized or died as a result of injury during the years 1989-96. Multivariate logistic regression was used to identify and adjust for confounding variables. RESULTS: There were 3145 cases and 8371 controls. The adjusted odds ratio for injury in children with an older sibling was 1.50 (95% confidence interval 1.37 to 1.65). The effect was greatest in children under 2 years of age, and in those with a birth interval of less than two years. As the number of older siblings increased, so did the risk of injury, with the highest risk in children with three or more older siblings. CONCLUSION: These data suggest that the presence of an older sibling is associated with an increased risk of injury. The risk is highest in those with very short birth intervals. Potential mechanisms for this increased risk may relate to inadequate parental supervision. Pediatricians and other care providers need to be alert to these identifiable risk factors and then direct preventive strategies, such as home visits and educational programs, toward these families. (+info)
Maternal morbidity and mortality associated with interpregnancy interval: cross sectional study.
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OBJECTIVE: To study the impact of interpregnancy interval on maternal morbidity and mortality. DESIGN: Retrospective cross sectional study with data from the Perinatal Information System database of the Latin American Centre for Perinatology and Human Development, Montevideo, Uruguay. SETTING: Latin America and the Caribbean, 1985-97. PARTICIPANTS: 456 889 parous women delivering singleton infants. MAIN OUTCOME MEASURES: Crude and adjusted odds ratios of the effects of short and long interpregnancy intervals on maternal death, pre-eclampsia, eclampsia, gestational diabetes mellitus, third trimester bleeding, premature rupture of membranes, postpartum haemorrhage, puerperal endometritis, and anaemia. RESULTS: Short (<6 months) and long (>59 months) interpregnancy intervals were observed for 2.8% and 19.5% of women, respectively. After adjustment for major confounding factors, compared with those conceiving at 18 to 23 months after a previous birth, women with interpregnancy intervals of 5 months or less had higher risks for maternal death (odds ratio 2.54; 95% confidence interval 1.22 to 5.38), third trimester bleeding (1.73; 1.42 to 2.24), premature rupture of membranes (1.72; 1.53 to 1.93), puerperal endometritis (1.33; 1.22 to 1.45), and anaemia (1.30; 1.18 to 1.43). Compared with women with interpregnancy intervals of 18 to 23 months, women with interpregnancy intervals longer than 59 months had significantly increased risks of pre-eclampsia (1.83; 1.72 to 1.94) and eclampsia (1.80; 1.38 to 2.32). CONCLUSIONS: Interpregnancy intervals less than 6 months and longer than 59 months are associated with an increased risk of adverse maternal outcomes. (+info)
Reproductive investment in pre-industrial humans: the consequences of offspring number, gender and survival.
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The number and gender of offspring produced in a current reproductive event can affect a mother's future reproductive investment and success. I studied the subsequent reproductive outcome of pre-industrial (1752-1850) Finnish mothers producing twins versus singletons of differing gender. I predicted that giving birth to and raising twins instead of singletons, and males instead of females, would incur a greater reproductive effort and, hence, lead to larger future reproductive costs for mothers. I compared the mothers' likelihood of reproducing again in the future, their time to next reproduction and the gender and survival of their next offspring. I found that mothers who produced twins were more likely to stop breeding or breed unsuccessfully in the future as compared with women of a similar age and reproductive history who produced a same-gender singleton child. As predicted, the survival and gender of the offspring produced modified the costs of reproduction for the mothers. Giving birth to and raising males generally appeared to be the most expensive strategy, but this effect was only detected in mothers who produced twins and, thus, suffering from higher overall costs of reproduction. (+info)
Effect of interpregnancy interval on risk of spontaneous preterm birth in Emirati women, United Arab Emirates.
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OBJECTIVE: To investigate whether a short interpregnancy interval is a risk factor for preterm birth in Emirati women, where there is a wide range of interpregnancy intervals and uniformity in potentially confounding factors. METHODS: A case-control design based on medical records was used. A case was defined as a healthy multiparous Emirati woman delivering a healthy singleton spontaneously before 37 weeks of gestation between 1997 and 2000, and a control was defined as the next eligible similar woman delivering after 37 weeks of gestation. Women were excluded if there was no information available about their most recent previous pregnancy or if it had resulted in a multiple or preterm birth. Data collected from charts and delivery room records were analysed using the STATA statistical package. All variables found to be valid, stable and significant by univariate analysis were included in multivariate logistic regression analysis. FINDINGS: There were 128 cases who met the eligibility criteria; 128 controls were selected. Short interpregnancy intervals were significantly associated with case status (P<0.05). The multivariate adjusted odds ratios for the 1st, 2nd, and 4th quartiles of interpregnancy interval compared with the lowest-risk 3rd quartile were 8.2, 5.4, and 2.0 (95% confidence intervals: 3.5-19.2, 2.4-12.6, and 0.9- 4.5 respectively). CONCLUSION: A short interpregnancy interval is a risk factor for spontaneous preterm birth in Emirati women. The magnitude of the risk and the risk gradient between exposure quartiles suggest that the risk factor is causal and that its modification would reduce the risk of preterm birth. (+info)