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Short and long intervals between successive births are associated with adverse birth outcomes, especially in low-income and middle-income countries, yet the birth intervals in high-income countries remain relatively understudied. The aim was to examine maternal factors associated with birth intervals in Australia.The sample comprised 6130 participants in the Australian Longitudinal Study on Women's Health who were born in 1973-1978, had two or more births, and responded to regular surveys between 1996 and 2018. Interbirth interval (IBI) was defined as the time between successive live births. Maternal factors were examined using accelerated failure time models.For women with only two births (n = 3802), the median time to the second birth was 34.0 months (IQR 23.1, 46.2) with shorter IBI associated with higher socioeconomic status (eg, university education (31.9 months), less income stress (31.1)), and longer IBI associated with age over 35 (39.7), fair/poor health (43.0), untreated fertility problems (45.5), miscarriage (39.4), or abortion (41.0). For women with three or more births (n = 2328), the median times to the second and third births were 31.2 months (19.9, 42.1) and 36.5 months (25.3, 50.1), respectively; some factors were consistent between the first IBI and second IBI (eg, university education and being married were associated with shorter IBI), whereas income stress was associated with longer first IBI but not with second IBI.Understanding maternal factors associated with birth intervals in a high-income country like Australia may enable more nuanced tailoring of guidelines for prepregnancy care.

BackgroundMaternal age 34 years, short inter-pregnancy birth interval, and higher birth order are considered to be high-risk fertility behaviours (HRFB). Underfive mortality being disproportionately concentrated in Asia and Africa, this study analyses the association between HRFB and underfive mortality in selected Asian and African countries.MethodsThis study used Integrated Public Microdata Series-Demographic and Health Surveys (IPUMS-DHS) data from 32 countries in sub-Saharan Africa, Middle East, North Africa and South Asia from 1986 to 2017 (N = 1,467,728). Previous evidence hints at four markers of HRFB: women’s age at birth of index child 34 years, preceding birth interval 3. Using logistic regression, we analysed change in the odds of underfive mortality as a result of i) exposure to HRFB individually, ii) exposure to any single HRFB risk factor, iii) exposure to multiple HRFB risk factors, and iv) exposure to specific combinations of HRFB risk factors.ResultsMother’s age at birth of index child 3 was a protective factor. Presence of any single HRFB was associated with 7% higher risk of underfive mortality (OR 1.07; 95% CI 1.04–1.09). Presence of multiple HRFBs was associated with 39% higher risk of underfive mortality (OR 1.39; 95% CI 1.36–1.43). Some specific combinations of HRFB such as maternal age ConclusionMaternal age

BackgroundFertility rates remain persistently high in Nigeria, with little difference across socioeconomic groups. While the desire for large family size is culturally rooted, there is little understanding of how repeated child mortality experiences influence fertility behaviour and parity transition in Nigeria.MethodsUsing birth history data from the 2013 Nigeria Demographic and Health Survey (NDHS), we applied life table techniques and proportional-hazard regression model to explore the effect of child survival experience on parity transitions. We hypothesize that a woman with one or more child death experience is at elevated risk of progressing towards higher parities.ResultsOur findings show that child mortality is concentrated among mothers living in deprived conditions especially in rural areas of the northern part of Nigeria and among those with little or no education and, among those belonging to Hausa/Fulani ethnicity and Islam religion. Mothers with repeated experience of child deaths were significantly at a higher rate of progressing to higher parities than their counterparts (HR: 1.45; 95% CI: 1.31–1.61), when adjusted for relevant biological and socio-demographic characteristics.ConclusionRecurrent experience of child deaths exacerbates the risks to higher parity transition. Interventions aimed at reducing fertility in Nigeria should target promoting child survival and family planning concurrently.

Background This systematic review summarises association between short interpregnancy intervals and adverse perinatal health outcomes in high‐resource settings to inform recommendations for healthy birth spacing for the United States. Methods Five databases and a previous systematic review were searched for relevant articles published between 1966 and 1 May 2017. We included studies meeting the following criteria: (a) reporting of perinatal health outcomes after a short interpregnancy interval since last livebirth; (b) conducted within a high‐resource setting; and (c) estimates were adjusted for maternal age and at least one socio‐economic factor. Results Nine good‐quality and 18 fair‐quality studies were identified. Interpregnancy intervals

Background In low-income nations, high-risk fertility behavior is a prevalent public health concern that can be ascribed to unmet family planning needs, child marriage, and a weak health system. As a result, this study aimed to determine the factors that influence high-risk fertility behavior and its impact on child stunting and anemia. Method This study relied on secondary data sources from recent demography and health surveys of nine east African countries. Relevant data were extracted from Kids Record (KR) files and appended for the final analysis; 31,873 mother-child pairs were included in the final analysis. The mixed-effect logistic regression model (fixed and random effects) was used to describe the determinants of high-risk fertility behavior (HRFB) and its correlation with child stunting and anemia. Result According to the pooled study about 57.6% (95% CI: 57.7 to 58.2) of women had at least one high-risk fertility behavior, with major disparities found across countries and women’s residences. Women who lived in rural areas, had healthcare access challenges, had a history of abortion, lived in better socio-economic conditions, and had antenatal care follow-up were more likely to engage in high-risk fertility practices. Consequently, Young maternal age at first birth ( Conclusion This study revealed that the magnitude of high-risk fertility behavior was higher in east Africa region. The finding of this study underscores that interventions focused on health education and behavioral change of women, and improvement of maternal healthcare access would be helpful to avert risky fertility behaviors. In brief, encouraging contraceptive utilization and creating awareness about birth spacing among reproductive-age women would be more helpful. Meanwhile, frequent nutritional screening and early intervention of children born from women who had high-risk fertility characteristics are mandatory to reduce the burden of chronic malnutrition.

Background Globally, infant mortality has declined considerably but has remained unacceptably high in sub-Saharan Africa, especially Nigeria where infant mortality rate is 67/1000 live births. To facilitate infant mortality reduction in Nigeria, an understanding of the synergistic effect of bio-demographic characteristics of mothers known as High Risk Birth Behaviours (HrBBs) is important. We therefore investigated the influence of HrBBs on infant survival in Nigeria. Methods This cross-sectional study design utilized data from the 2018 round of Nigerian Demographic Health Survey. The study participants were a representative sample of women of reproductive age (n = 21,350) who had given birth within the 5 years preceding the survey. HrBBs was measured through integration of information on maternal age at child’s birth, parity, and preceding birth interval with respect to the most recent child. The HrBBs was categorized as none, single and multiple. Data were analysed using descriptive statistics, Log-rank test and Cox proportional hazard model (α =0.05). Results The mean age of the women was 29.7 ± 7.2 and 4.1% had experienced infant death. Infant mortality was highest among women with multiple HrBBs (5.1%). Being a male, having small size at birth, failure to receive tetanus injection, non-use of contraceptives and living in the core-north (North West and North East) predisposed children to higher risk of dying before 12 months of age. The hazard ratio of infant mortality was significantly higher among infants of mothers in multiple HrBBs category (aHR = 1.66; CI: 1.33–2.06) compared to their counterparts with no HrBBs. Conclusion Multiple HrBBs increase the chances of dying among infants in Nigeria. Screening women for HrBBs for special health attention during pregnancy, birth and postnatal period will alleviate infant death in Nigeria.

Births in avoidable high-risk contexts defined by the interplay of sub-optimal childbearing age, short spacing, and first and high birth order incur elevated risks of childhood death. However, the extent of disparities in risks of dying in infancy vis-à-vis the continuum of non-high-risk and (un)avoidable high-risk attributes at birth as determined by mother's age at childbirth, child spacing, and birth order characteristics is yet to be adequately explored in Nigeria as elsewhere. To fill this gap, chi-square association test and Cox's proportional hazards regression were used to analyze data of 31,260 nationally representative children aged 0-59 months drawn from 2013 Nigeria Demographic and Health Survey. Disparities in infant mortality risks were mainly examined across the spectrum of birth-related risk attributes at birth broadly categorized as no extra high-risk, unavoidable first- order risk and combined avoidable high-risk. The risks of dying in infancy differed significantly by risk attributes to the extent dictated by other confounders. Also, infant mortality risks varied significantly by all moderating factors excluding religion, water source, toilet type and place of delivery. Interventions targeted at reducing avoidable high-risk fertility rate and strengthening health system to provide life-saving care to most-at-risk children would engender rapid improvement in infant survival.

Background The risk of a child dying before reaching 5 years of age is highest in sub-Saharan African countries. But in Ethiopia, under-five mortality rates have shown a substantial decline. Methods For this study, the Cox regression model for fixed and time-dependent explanatory variables was studied for under-five mortality in Ethiopia. We adapted survival analysis using the Cox regression model with 2011 Ethiopian Demographic and Health Survey data. Results From the results, it was found that under-five children who live in Addis Ababa had a lower hazard (risk) of death (p value = 0.048). This could be as a result of higher health facilities and living standards in Addis Ababa, compared to other regions. Under-five children who lived in rural areas had a higher hazard (risk) of death compared to those living in urban areas. In addition, under-five children who lived in rural areas had 18% (p value = 0.01) more hazard (risk) of death than those living in urban areas. Furthermore, with older mothers, the chance of a child dying before reaching the age of 5 is lower. Conclusion The chances of a child dying before reaching the age of 5 are less if the mother does not become pregnant again before the child reaches the age of 5. Therefore, giving birth when older and not becoming pregnant again before the child reaches the age of 5 is one means of reducing under-five mortality.

BACKGROUND: Several studies have examined the association between IPI and birth outcomes, but few have explored the association between interpregnancy interval (IPI) and postnatal outcomes. OBJECTIVE: We examined the association between IPI and injury-related infant mortality, a leading cause of postneonatal mortality. METHODS: We used 2011-2015 US period-linked birth-infant death vital statistics data to generate a multiyear birth cohort of non-first-born singleton births (N = 9 782 029). IPI was defined as the number of months between a live birth and the start of the pregnancy leading to the next live birth. Causes of death in the first year of life were identified using ICD-10 codes. Hazard ratios (HR) for IPI categories were estimated using Cox proportional hazards models adjusted for birth order, county poverty level, and maternal characteristics (marital status, race/ethnicity, education, age at previous birth). RESULTS: After adjustment, overall infant mortality (48.1 per 10 000 births) was higher for short and long IPIs compared with IPI 18-23 months (reference)

Background Currently, no federal guidelines provide recommendations on healthy birth spacing for women in the United States. This systematic review summarises associations between short interpregnancy intervals and adverse maternal outcomes to inform the development of birth spacing recommendations for the United States. Methods PubMed/Medline, POPLINE, EMBASE, CINAHL, the Cochrane Database of Systematic Reviews, and a previous systematic review were searched to identify relevant articles published from 1 January 2006 and 1 May 2017. Included studies reported maternal health outcomes following a short versus longer interpregnancy interval, were conducted in high‐resource settings, and adjusted estimates for at least maternal age. Two investigators independently assessed study quality and applicability using established methods. Results Seven cohort studies met inclusion criteria. There was limited but consistent evidence that short interpregnancy interval is associated with increased risk of precipitous labour and decreased risks of labour dystocia. There was some evidence that short interpregnancy interval is associated with increased risks of subsequent pre‐pregnancy obesity and gestational diabetes, and decreased risk of preeclampsia. Among women with a previous caesarean delivery, short interpregnancy interval was associated with increased risk of uterine rupture in one study. No studies reported outcomes related to maternal depression, interpregnancy weight gain, maternal anaemia, or maternal mortality. Conclusions In studies from high‐resource settings, short interpregnancy intervals are associated with both increased and decreased risks of adverse maternal outcomes. However, most outcomes were evaluated in single studies, and the strength of evidence supporting associations is low.

ObjectiveTo explore the association between high-risk fertility behaviours and the likelihood of chronic undernutrition, anaemia and the coexistence of anaemia and undernutrition among women of reproductive age.DesignThe 2011 Bangladesh Demographic and Health Survey, conducted from 8 July to 27 December 2011.SettingSelected urban and rural areas of Bangladesh.SubjectsA total of 2197 ever-married women living with at least one child younger than 5 years. Exposure was determined from maternal reports of high-risk fertility behaviours. We considered three parameters, maternal age at the time of delivery, birth order and birth interval, to define the high-risk fertility behaviours. Chronic undernutrition, anaemia and the coexistence of anaemia and undernutrition among women were the outcome variables.ResultsA substantial percentage of women were exposed to have a high-risk fertility pattern (41·8 %); 33·0 % were at single high-risk and 8·8 % were at multiple high-risk. After adjusting for relevant covariates, high-risk fertility behaviours were associated with increased likelihood of chronic undernutrition (adjusted relative risk; 95 % CI: 1·22; 1·03, 1·44), anaemia (1·12; 1·00, 1·25) and the coexistence of anaemia and undernutrition (1·52; 1·17, 1·98). Furthermore, multiple high-risk fertility behaviours appeared to have more profound consequences on the outcome measured.ConclusionsMaternal high-risk fertility behaviours are shockingly frequent practices among women in Bangladesh. High-risk fertility behaviours are important predictors of the increased likelihood of women’s chronic undernutrition, anaemia and the coexistence of anaemia and undernutrition.

Objective: To investigate the association of socioeconomic position (SEP) with reproductive outcomes among Australian women. Methods: Data from the Australian Longitudinal Study on Women’s Health’s (population-based cohort study) 1973–1978 cohort were used (N = 6899, aged 37–42 years in 2015). The association of SEP (childhood and own, multiple indicators) with age at first birth, birth-to-pregnancy (BTP) intervals and total number of children was analysed using multinomial logistic regression. Results: 14% of women had their first birth aged

Background Meta‐analyses of observational studies have shown that women with a shorter interpregnancy interval (the time from delivery to start of a subsequent pregnancy) are more likely to experience adverse pregnancy outcomes, such as preterm delivery or small for gestational age birth, than women who space their births further apart. However, the studies used to inform these estimates have methodological shortcomings. Methods In this commentary, we summarise the discussions of an expert workgroup describing good practices for the design, analysis, and interpretation of observational studies of interpregnancy interval and adverse perinatal health outcomes. Results We argue that inferences drawn from research in this field will be improved by careful attention to elements such as: (a) refining the research question to clarify whether the goal is to estimate a causal effect vs describe patterns of association; (b) using directed acyclic graphs to represent potential causal networks and guide the analytic plan of studies seeking to estimate causal effects; (c) assessing how miscarriages and pregnancy terminations may have influenced interpregnancy interval classifications; (d) specifying how key factors such as previous pregnancy loss, pregnancy intention, and maternal socio‐economic position will be considered; and (e) examining if the association between interpregnancy interval and perinatal outcome differs by factors such as maternal age. Conclusion This commentary outlines the discussions of this recent expert workgroup, and describes several suggested principles for study design and analysis that could mitigate many potential sources of bias.

Examine the evolution of stunting in5 years of age in Peru and its relationship with birth interval (BI), and associated factors from 1996 to 2014.Data were extracted from the National Demographic and Health Survey of Peru (DHS) for the years 1996, 2000, 2005, 2010 and 2014 on children5 years of age for stunting (height / age ≤ 2DS). The main independent variable of interest was BI dichotomized by interval between date of last and penultimate birth (≤24 months vs.24 months) and others sociodemographic variables. Crude and adjusted odds ratios with 95% confidence intervals were estimated in logistic regression for the effect of BI and other variables on stunting by each survey year.Between 1996 and 2014, stunting declined in both BI groups: ≤24 months: 35.8% to 21.8%;24 months: 29.5% to 14.3%. BI was associated with stunting after adjustment for other variables in each survey except 2005. Of the other factors, sex, birth order (fourth child or more), maternal education and poverty were independently associated with stunting in all survey years. Residence in rural areas and in Amazon forest and highland regions was associated with stunting 1996 and 2000. Maternal age was not independently associated with stunting.While stunting showed a decreasing trend from 1996 to 2014, birth interval exceeding 24 months exerted a protective effect on stunting across the years surveyed. Poverty, low maternal education and high birth order were associated with stunting in all survey years.

Data from the National Vital Statistics System •Nearly 29.0% of U.S. mothers who had a second or higher-order birth in 2014 had a short interpregnancy interval of less than 18 months. •Short intervals (i.e., less than 6 months, 6-11 months, and 12-17 months) were more common for mothers aged 35 and over (5.7%, 16.3%, and 22.1%, respectively) than mothers who were under age 20 at their previous birth (5.1%, 8.8%, and 8.4%). •Short intervals of less than 6 months and 6-11 months were more common among non-Hispanic black mothers (7.1% and 11.7%, respectively) than non-Hispanic white mothers (4.1% and 11.2%) and Hispanic mothers (5.0% and 9.3%). •The percentage of births to mothers with intervals less than 6 months decreased as education level increased, from 4.3% (no high school diploma) to 1.8% (doctorate or professional degree).

The increased reach of health programs in India during the past few decades has contributed to a decline in postnatal mortality including infant and child mortality; however, reduction in neonatal mortality remained negligible. About seven out of ten neonatal deaths take place within a week after birth. The progress in reduction as well as dimension along which early neonatal mortality is patterned in India remains unclear. We examine the trend in early neonatal mortality and its possible demographic and socioeconomic predictors using nationally representative data. Data from the three cross-sectional rounds of the National Family Health Survey of India from 1992 to 1993, 1998 to 1999 and 2005 to 2006 were analyzed. Early neonatal mortality rate was estimated for selected demographic and socioeconomic population groups and for major states in India using information on births and deaths during the 3 years preceding the respective surveys. Using the multivariate logistic regression model, we assessed proximate determinants of early neonatal deaths during 1990-2006. Sex of the child, child's birth size, birth order and interval, type of child's birth, mother's age at child's birth, mother's educational status, religion, household economic status and region of residence emerged as significant predictors of early neonatal deaths. The adjusted multivariate analysis indicates that majority of the socio-demographic predictors reveal a negligible decline in the probability of early neonatal deaths during 1990-2006. Moreover, based on comprehensive reviews of scientific literature on newborn's survival we document some of the recommended ways to prevent early neonatal mortality in India.

There is growing interest in the application of propensity scores (PS) in epidemiologic studies, especially within the field of reproductive epidemiology. This retrospective cohort study assesses the impact of a short interpregnancy interval (IPI) on preterm birth and compares the results of the conventional logistic regression analysis with analyses utilizing a PS. The study included 96,378 singleton infants from Louisiana birth certificate data (1995-2007). Five regression models designed for methods comparison are presented. Ten percent (10.17 %) of all births were preterm; 26.83 % of births were from a short IPI. The PS-adjusted model produced a more conservative estimate of the exposure variable compared to the conventional logistic regression method (β-coefficient: 0.21 vs. 0.43), as well as a smaller standard error (0.024 vs. 0.028), odds ratio and 95 % confidence intervals [1.15 (1.09, 1.20) vs. 1.23 (1.17, 1.30)]. The inclusion of more covariate and interaction terms in the PS did not change the estimates of the exposure variable. This analysis indicates that PS-adjusted regression may be appropriate for validation of conventional methods in a large dataset with a fairly common outcome. PS's may be beneficial in producing more precise estimates, especially for models with many confounders and effect modifiers and where conventional adjustment with logistic regression is unsatisfactory. Short intervals between pregnancies are associated with preterm birth in this population, according to either technique. Birth spacing is an issue that women have some control over. Educational interventions, including birth control, should be applied during prenatal visits and following delivery.

Background Low birth weight (LBW) is closely associated with foetal and neonatal mortality and morbidity, inhibite growth and cognitive development and resulted chronic diseases later in life. Many factors affect foetal growth and thus, the birth weight. These factors operate to various extents in different environments and cultures. The prevalence of low birth weight in the study area is the highest in the country. To the investigator’s knowledge in Bale Zone, no study has yet been done to elucidate the risk factors for low birth weight using case control study design. This study was aimed to identify the risk factors of low birth weight in Bale zone hospitals. Methods A case–control study design was applied from April 1st to August 30th, 2013. A total of 387 mothers (136 cases and 272 controls) were interviewed using structured and pretested questionnaire by trained data collectors working in delivery ward. For each case, two consecutive controls were included in the study. All cases and controls were mothers with singleton birth, full term babies, no diabetes mellitus and no hypertensive. The data were entered and analyzed using SPSS version 16.0 statistical package. The association between the independent variables and dependent variable (birth weight) was evaluated through bivariate and multiple logistic regression analyses. Result Maternal age at delivery

Prior research indicates that closely spaced births are associated with poor outcomes for the mother and subsequent child. Limited research has focused on outcomes for the index child (the child born immediately prior to a subsequent child in a birth interval). The objectives are to assess the association of short birth intervals in at-risk families with: (1) indicators of harsh and neglectful parenting behaviors towards the index child, including substantiated maltreatment reports across 6 years; and (2) the index child's behavior and development in first grade. This is a longitudinal study of 658 women screened to be at-risk for child maltreatment. Twenty percent of women had a rapid repeat birth (RRB), defined as the birth of a subsequent child within 24 months of the index child. Generalized estimating equations, survival analyses, and linear and logistic regression models were used to assess the associations between RRB and index child outcomes. Women with an RRB were more likely than those without an RRB to report neglectful parenting of the index child. Children of mothers with an RRB were more likely than children of mothers without an RRB to have more behavioral problems and lower cognitive functioning in first grade. This study is among the first to focus on the associations of birth spacing with maltreatment, behavior and development outcomes in the index child. Future work regarding the effects of birth spacing should include a focus on the index child.

Background: Age at first and last birth and the number of children are known to influence the risk of endometrial and ovarian cancers. However, it remains unknown whether the difference in years between first and last childbirth plays a role. The Swedish Family-Cancer Database allowed us to carry out the largest study ever on reproductive factors in these cancers. Material and methods: We selected over 5.7 million women from the database. We estimated the effect of number of children, age at birth and difference between age at first and last birth by Poisson regression adjusted for age, period, region and socioeconomic status. Results: The risk for endometrial cancer is negatively associated with increasing number of children and increasing age at first as well as age at last birth. Weaker associations are found for ovarian cancer. Age at last birth is the factor that shows highest influence. A large difference in first and last childbirth shows a protective effect on the risk of endometrial cancer. Conclusion: Our findings suggest that the risk of endometrial cancer is significantly decreased for women having at least a difference of 10 years between their first and last birth. Ovarian cancer does not seem to be influenced by the time interval between first and last birth. (c) 2010 Elsevier Ltd. All rights reserved. (Less)

Summary Objective Establishment of a primary healthcare network in Iran has provided free and universal access to primary health care. Although the health status of Iranians has improved since this network was established, the low-birthweight rate has not decreased. The objective of the present study was to describe socio-economic and medical factors related to low birth weight in the context of free and universal access to primary health care. Design Descriptive, hospital-based prospective study. Methods Data about socio-economic, reproductive and prenatal condition of 4510 live singleton births from June to October 2004 were gathered using a standard questionnaire by interview and record review. The effect of these conditions on birth weight was investigated using a logistic regression model. Results Of 4510 newborns, 305 (6.8%) were low birth weight. Among these low-birthweight newborns, there were 159 preterm and 146 term newborns. Mothers with a primary and secondary education [odds ratio (OR) 6.83, 95% confidence interval (CI) 2.35–7.34 and OR 4.81, 95%CI 1.95–6.37, respectively], who lived with farmer and unskilled worker husbands (OR 2.52, 95%CI 1.12–4.66 and OR 2.91, 95%CI 1.35–2.52, respectively), with a birth interval of 1 year or less (OR 3.54, 95%CI 1.80–5.95) and height less than 155 cm (OR 1.82, 95%CI 1.12–3.31) were more likely to have low-birthweight infants. Conclusion In the context of free and universal access to health care, it is recommended that policy makers should place more emphasis on education as it imparts knowledge and thus influences dietary habits and birth-spacing behaviour. This will lead to a better nutritional status, particularly in dealing with pregnancy, resulting in lower rates of low birth weight.

Background: Traditional contraceptive methods (TCMs) have been used by our ancestors for a long time in child spacing before the advent of the modern contraceptive methods but even with the introduction of the modern methods some women prefer and are still using TCMs. Aim: The aim of this study was to assess the utilization of traditional contraceptives in child spacing and its association with family size among women of child-bearing age attending primary healthcare centers in Kano. Materials and Methods: This was a cross-sectional study among 400 women attending primary healthcare centers in Kano. Their sociodemographic characteristics, number of children, knowledge, and use of traditional contraceptives were recorded on a pretested questionnaire. Results: The mean age ± standard deviation (SD) was 29.1 ± 6.22 years. The mean number of children (±SD) was 3.9 ± 2.27. A total number of 280 (70.0%) participants knew about TCMs, but only 147 (36.8%) used these methods and among those that used TCMs, herbal medicine was the most used method (n = 67, 45.6%). There was no statistically significant difference between the mean number of children of the respondents who used traditional contraceptives and those who did not (t = 0.382, df = 398, P = 0.703, 95% confidence interval:−0.374–0.555). Educational status was significantly associated with the use of traditional contraceptives (χ2 = 8.327, P = 0.005). Conclusion: There was more knowledge of traditional than modern contraceptive methods. Herbal medicine was the most commonly used method. There was poor utilization of the modern contraceptive methods and fair utilization of the TCMs. The study showed no clear benefit of traditional contraceptive usage over its nonuse in reducing family size.

Human reproductive patterns have been well studied, but the mechanisms by which physiology, ecology and existing kin interact to affect the life history need quantification. Here, we create a model to investigate how age-specific interbirth intervals adapt to environmental and intrinsic mortality, and how birth patterns can be shaped by competition and help between siblings. The model provides a flexible framework for studying the processes underlying human reproductive scheduling. We developed a state-based optimality model to determine age-dependent and family-dependent sets of reproductive strategies, including the state of the mother and her offspring. We parameterized the model with realistic mortality curves derived from five human populations. Overall, optimal birth intervals increase until the age of 30 after which they remain relatively constant until the end of the reproductive lifespan. Offspring helping each other does not have much effect on birth intervals. Increasing infant and senescent mortality in different populations decreases interbirth intervals. We show that sibling competition and infant mortality interact to lengthen interbirth intervals. In lower-mortality populations, intense sibling competition pushes births further apart. Varying the adult risk of mortality alone has no effect on birth intervals between populations; competition between offspring drives the differences in birth intervals only when infant mortality is low. These results are relevant to understanding the demographic transition, because our model predicts that sibling competition becomes an important determinant of optimal interbirth intervals only when mortality is low, as in post-transition societies. We do not predict that these effects alone can select for menopause.