An exploratory spatial analysis of geographical inequalities of birth intervals among young women in the Democratic Republic of Congo (DRC): a cross-sectional study

BACKGROUND

The length of time between two successive live births (birth interval), is associated with child survival in the developing world. Short birth intervals (<24 months) contribute to infant and child mortality risks. Contraceptive use contributes to a reduction in short birth intervals, but evidence is lacking in the DRC. We aimed to investigate the proportion of short birth intervals at the provincial level among young women in the DRC.

METHODS

Data from the Demographic and Health Survey undertaken in the DRC in 2007 were analyzed. Logistic regression and Bayesian geo-additive models were used to explain provincial inequalities in short birth intervals among women of reproductive age and young women. Posterior odds ratio (OR) and 95% credible region (CR) were estimated via Markov chain Monte Carlo (MCMC) techniques. Posterior spatial effects and the associated posterior probability maps were produced at the provincial-level to highlight provinces with a significant higher risk of short birth interval.

RESULTS

The overall proportion of short birth intervals among all women of reproductive age (15-49 years) and young women (15-24 years) were 30.2% and 38.7% respectively. In multivariate Bayesian geo-additive regression analyses, among the whole sample of women, living in rural areas [OR = 1.07, 95% CR: (0.97, 1.17)], exclusive breastfeeding [1.08 (1.00, 1.17)] and women with primary education [1.06 (1.00, 1.16)], were consistently associated with a higher risk of short birth intervals. For the young women, none of the factors considered were associated with the risk of short birth interval except a marginal effect from the lack of education. There was a spatial variation in the proportion of women reporting short birth intervals and among all women of reproductive age across provinces, with Nord-Kivu [1.12 (1.02, 1.24)], Sud Kivu [1.17 (1.05, 1.29)] and Kasai Occidental [1.18 (1.06, 1.32)] reporting a higher risk of short birth intervals. For young women, the higher risk provinces were Nord-Kivu [1.22 (1.00, 1.54)] and Sud Kivu [1.34 (1.14, 1.63)].

CONCLUSIONS

This study suggests distinct geographic patterns in the proportion of short birth intervals among Congolese women, as well as the potential role of demographic and geographic location factors driving the ongoing higher youth fertility, higher childhood and maternal mortality in the DRC.

Relationship between interpregnancy interval and congenital anomalies

OBJECTIVE

To assess the association between interpregnancy intervals and congenital anomalies.

STUDY DESIGN

A retrospective cohort study on women who had 2 consecutive singleton births from 1999-2007 was conducted using a linked dataset from the Alberta Perinatal Health Program, the Alberta Congenital Anomalies Surveillance System, and the Alberta Health and Wellness Database. Interpregnancy interval was calculated as the interval between 2 consecutive deliveries minus the gestational age of the second infant. The primary outcome of congenital anomaly was defined using the International Classification of Diseases. Maternal demographic and obstetric characteristics and interpregnancy intervals were included in multivariable logistic regression models for congenital anomalies.

RESULTS

The study included 46,243 women, and the overall rate of congenital anomalies was 2.2%. Both short and long interpregnancy intervals were associated with congenital anomalies. The lowest rate was for the 12-17 months category (1.9%, reference category), and increased rates were seen for both short intervals (2.5% for 0-5 months; adjusted odds ratio, 1.32; 95% confidence interval, 1.01-1.72) and long intervals (2.3% for 24-35 months; adjusted odds ratio, 1.25; 95% confidence interval, 1.02-1.52). Statistically significant associations were also observed for folate independent anomalies, but not for folate dependent anomalies.

CONCLUSION

The risk of congenital anomalies appears to increase with both short and long interpregnancy intervals. This study supports the limited existing studies in the literature, further explores the types of anomalies affected, and has implications for further research and prenatal risk assessment.

Predictors of anemia among haitian children aged 6 to 59 months and women of childbearing age and their implications for programming

BACKGROUND

The Haitian National Nutrition Policy prioritizes prevention and treatment of anemia among mothers and young children, but there are few available data to support planning for scale-up of anemia interventions.

OBJECTIVE

To describe the prevalence and predictors of anemia among Haitian women (15 to 49 years) and children (6 to 59 months) and to draw implications for national nutrition programming.

METHODS

Descriptive and univariate analyses and multivariate logistic regression models were performed using data from the nationally representative Haitian Demographic Health Survey 2005/06.

RESULTS

The prevalence of mild (hemoglobin 11.0 to 11.9 g/dL), moderate (hemoglobin 8.0 to 10.9 g/dL), and severe (hemoglobin < 8.0 g/dL) anemia was 19.2%, 21.7%, and 4.4%, respectively, among women aged 15 to 49 years and 22.9%, 33.9%. and 2.2% among children aged 6 to 59 months. Unexpectedly anemia was more prevalent in urban women (54.4 %) and children (65.1%) than in rural women (43.1%, p < .001) and children (55.7%, p = .004). In multivariate regression models, factors associated with anemia among urban women (birth spacing, p = .027; overweight BMI, p < .001; education level, p = .022) were different from those in rural women (wealth quintile, p < .05; employment, p = .003). Anemia in urban and rural children aged 6 to 59 months increased with child age (p < .05) and maternal anemia status (p = .004; p < .001). Female sex (p = .007) and maternal overweight (p = .009) were associated with reduced risk of anemia in rural children only.

CONCLUSIONS

Anemia among Haitian young children and women of childbearing age is a severe public health problem. The findings suggest the need for context-specific rural and urban strategies, reinforcement of anemia prevention in health services reaching women of childbearing age, and targeted interventions for young children.

Effect of maternal-child home visitation on pregnancy spacing for first-time Latina mothers

OBJECTIVES

We examined the impact of a maternal-child home visitation program on birth spacing for first-time Latina mothers, focusing on adolescents and women who identified as Mexican or Puerto Rican.

METHODS

This was a retrospective cohort study. One thousand Latina women enrolled in the Pennsylvania Nurse-Family Partnership between January 1, 2003, and December 31, 2007, were matched to nonenrolled Latina women using propensity scores. The primary outcome was the time to second pregnancy that resulted in a live birth (interpregnancy interval). Proportional hazards models and bootstrap methods compared the time to event.

RESULTS

Home visitation was associated with a small decrease in the risk of a short interpregnancy interval (≤ 18 months) among Latina women (hazards ratio [HR] = 0.86; 95% confidence interval [CI] = 0.75, 0.99). This effect was driven by outcomes among younger adolescent women (HR = 0.80; 95% CI = 0.65, 0.96). There was also a trend toward significance for women of Mexican heritage (HR = 0.74; 95% CI = 0.49, 1.07), although this effect might be attributed to individual agency performance.

CONCLUSIONS

Home visitation using the Nurse-Family Partnership model had measurable effects on birth spacing in Latina women.

Household context and child mortality in rural South Africa: the effects of birth spacing, shared mortality, household composition and socio-economic status

BACKGROUND

Household characteristics are important influences on the risk of child death. However, little is known about this influence in HIV-endemic areas. We describe the effects of household characteristics on children's risk of dying in rural South Africa.

METHODS

We use data describing the mortality of children younger than 5 years living in the Agincourt health and socio-demographic surveillance system study population in rural northeast South Africa during the period 1994-2008. Using discrete time event history analysis we estimate children's probability of dying by child characteristics and household composition (other children and adults other than parents) (N=924,818 child-months), and household socio-economic status (N=501,732 child-months).

RESULTS

Children under 24 months of age whose subsequent sibling was born within 11 months experience increased odds of dying (OR 2.5; 95% CI 1.1-5.7). Children also experience increased odds of dying in the period 6 months (OR 2.1; 95% CI 1.2-3.6), 3-5 months (OR 3.0; 95% CI 1.5-5.9), and 2 months (OR 11.8; 95% CI 7.6-18.3) before another household child dies. The odds of dying remain high at the time of another child's death (OR 11.7; 95% CI 6.3-21.7) and for the 2 months following (OR 4.0; 95% CI 1.9-8.6). Having a related but non-parent adult aged 20-59 years in the household reduces the odds (OR 0.6; 95% CI 0.5-0.8). There is an inverse relationship between a child's odds of dying and household socio-economic status.

CONCLUSIONS

This detailed household profile from a poor rural setting where HIV infection is endemic indicates that children are at high risk of dying when another child is very ill or has recently died. Short birth intervals and additional children in the household are further risk factors. Presence of a related adult is protective, as is higher socio-economic status. Such evidence can inform primary health care practice and facilitate targeting of community health worker efforts, especially when covering defined catchment areas.

Evidence-based interventions for improvement of maternal and child nutrition: what can be done and at what cost?

Maternal undernutrition contributes to 800,000 neonatal deaths annually through small for gestational age births; stunting, wasting, and micronutrient deficiencies are estimated to underlie nearly 3·1 million child deaths annually. Progress has been made with many interventions implemented at scale and the evidence for effectiveness of nutrition interventions and delivery strategies has grown since The Lancet Series on Maternal and Child Undernutrition in 2008. We did a comprehensive update of interventions to address undernutrition and micronutrient deficiencies in women and children and used standard methods to assess emerging new evidence for delivery platforms. We modelled the effect on lives saved and cost of these interventions in the 34 countries that have 90% of the world's children with stunted growth. We also examined the effect of various delivery platforms and delivery options using community health workers to engage poor populations and promote behaviour change, access and uptake of interventions. Our analysis suggests the current total of deaths in children younger than 5 years can be reduced by 15% if populations can access ten evidence-based nutrition interventions at 90% coverage. Additionally, access to and uptake of iodised salt can alleviate iodine deficiency and improve health outcomes. Accelerated gains are possible and about a fifth of the existing burden of stunting can be averted using these approaches, if access is improved in this way. The estimated total additional annual cost involved for scaling up access to these ten direct nutrition interventions in the 34 focus countries is Int$9·6 billion per year. Continued investments in nutrition-specific interventions to avert maternal and child undernutrition and micronutrient deficiencies through community engagement and delivery strategies that can reach poor segments of the population at greatest risk can make a great difference. If this improved access is linked to nutrition-sensitive approaches--ie, women's empowerment, agriculture, food systems, education, employment, social protection, and safety nets--they can greatly accelerate progress in countries with the highest burden of maternal and child undernutrition and mortality.

Short preceding birth intervals and child mortality in Mozambique

This paper examines the risk of child mortality associated with short preceding birth intervals in Mozambique. We apply a piecewise log-rate model to a pooled dataset comprising 36,305 live births from the 1997 and 2003 Mozambique Demographic and Health Surveys (DHS). Our results show that the effects of short preceding intervals are strongest during the first month of life, particularly the first week, indicating prenatal maternal depletion as the dominant pathway. The rapid decline in mortality rates from intervals of less than six months to the category 30 to 35 months suggests an optimal waiting period of at least 30 months between one birth and the next pregnancy. 73 per cent of births had preceding intervals less than 30 months which, amidst low contraception use, indicates a potential for family planning programs to contribute to child survival and the attainment of Millennium Development Goal 4 in Mozambique.

Prenatal care and subsequent birth intervals

CONTEXT

Prenatal care generally includes contraceptive and health education that may help women to control their subsequent fertility. However, research has not examined whether receipt of prenatal care is associated with subsequent birthspacing.

METHODS

Longitudinally linked birth records from 113,662 New Jersey women who had had a first birth in 1996-2000 were used to examine associations between the timing and adequacy of prenatal care prior to a woman's first birth and the timing of her second birth. Multinomial logistic regression analyses adjusted for social and demographic characteristics, hospital and year of birth.

RESULTS

Most women (85%) had initiated prenatal care during the first trimester. Women who had not obtained prenatal care until the second or third trimester, or at all, were more likely than those who had had first-trimester care to have a second child within 18 months, rather than in 18-59 months (odds ratios, 1.2-1.6). Similarly, women whose care had been inadequate were more likely than those who had had adequate care to have a short subsequent birth interval (1.2). The associations were robust to alternative measures of prenatal care and birth intervals, and were strongest for mothers with less than 16 years of education.

CONCLUSIONS

Providers should capitalize on their limited encounters with mothers who initiate prenatal care late or use it sporadically to ensure that these women receive information about family planning.

A longitudinal analysis of the relationship between fertility timing and schooling

This article quantifies the contribution of pre-treatment dynamic selection to the relationship between fertility timing and postsecondary attainment, after controlling for a rich set of predetermined characteristics. Eventual mothers and nonmothers are matched using their predicted birth hazard rate, which shares the desirable properties of a propensity score but in a multivalued treatment setting. I find that eventual mothers and matched nonmothers enter college at the same rate, but their educational paths diverge well before the former become pregnant. This pre-pregnancy divergence creates substantial differences in ultimate educational attainment that cannot possibly be due to the childbirth itself. Controls for predetermined characteristics and fixed effects do not address this form of dynamic selection bias. A dynamic model of the simultaneous childbirth-education sequencing decision is necessary to address it.

Sex of preceding child and birth spacing among Nigerian ethnic groups

In seeking for more effective ways of fertility control and improvement of maternal and child health through birth spacing in a predominantly patrilineal society like Nigeria, this study explores how the sex of a previous child affects birth interval among ethnic groups, controlling for demographic and socioeconomic variables. The study utilized birth history data from the 2008 Nigeria Demographic and Health Survey. The findings showed that the effect of sex of prior births on the birth interval is slightly significant among the Igbo and the Southern minorities, who tend to desire to have a male child sooner if preceding births were female. Among all the ethnic groups, women who are yet to meet their ideal sex preference have a shorter birth interval than those who have. Apart from the evident sex preferences, these results suggest that Nigerian parents also undertake sex balancing among their children. There is a consistent and strong relationship between the survival of a child and subsequent birth interval, which suggest that women have a short birth interval, and hence a large family size, because they are not certain that their children would survive.

Effect of interpregnancy interval on outcomes of pregnancy after miscarriage: retrospective analysis of hospital episode statistics in Scotland

OBJECTIVE

To determine the optimum interpregnancy interval after miscarriage in a first recorded pregnancy.

DESIGN

Population based retrospective cohort study.

SETTING

Scottish hospitals between 1981 and 2000.

PARTICIPANTS

30,937 women who had a miscarriage in their first recorded pregnancy and subsequently became pregnant.

MAIN OUTCOME MEASURES

The primary end point was miscarriage, live birth, termination, stillbirth, or ectopic pregnancy in the second pregnancy. Secondary outcomes were rates of caesarean section and preterm delivery, low birthweight infants, pre-eclampsia, placenta praevia, placental abruption, and induced labour in the second pregnancy.

RESULTS

Compared with women with an interpregnancy interval of 6-12 months, those who conceived again within six months were less likely to have another miscarriage (adjusted odds ratio 0.66, 95% confidence interval 0.57 to 0.77), termination (0.43, 0.33 to 0.57), or ectopic pregnancy (0.48, 0.34 to 0.69). Women with an interpregnancy interval of more than 24 months were more likely to have an ectopic second pregnancy (1.97, 1.42 to 2.72) or termination (2.40, 1.91 to 3.01). Compared with women with an interpregnancy interval of 6-12 months, women who conceived again within six months and went on to have a live birth in the second pregnancy were less likely to have a caesarean section (0.90, 0.83 to 0.98), preterm delivery (0.89, 0.81 to 0.98), or infant of low birth weight (0.84, 0.71 to 0.89) but were more likely to have an induced labour (1.08, 1.02 to 1.23).

CONCLUSIONS

Women who conceive within six months of an initial miscarriage have the best reproductive outcomes and lowest complication rates in a subsequent pregnancy.

The influence of birth spacing on child survival in Bangladesh: a life table approach

In this paper we have attempted to demonstrate the relationship between birth spacing and child survival in Bangladesh using data from the 2004 Bangladesh Demographic Health Survey (BDHS). We used standard life table techniques to estimate the probability of child survival and appropriate spacing of births. Logistic regression models were used to investigate the covariates, along with the birth interval that has significant influence on child survival. Study results showed that the probability of child survival was much lower when the preceding birth interval was less than 12 months, and it may be also impeded by a higher birth interval. Child survival probability was highest for a preceding birth interval of 5 years; thereafter, the probability declined. Results of the logistic regression model clearly showed that preceding birth interval was an important and strongly significant factor in explaining infant and child mortality. While education, current age, breastfeeding status and birth order were substantial and highly significant factors both in infant and child mortality, socio-economic factors such as occupation and socio-economic status showed a significant effect only on child mortality. Postponing another child (for a birth interval of 5 years and above) and proper spacing of births would have a noticeable effect in reducing the level of mortality.

The patterns and determinants of birth intervals in multiparous women in Babol, northern Iran

The present study aimed to determine the patterns and factors associated with birth intervals in multiparous women in Babol, northern Iran. We conducted a cross-sectional study of 500 multiparous women at health centers and referred to the hospital for delivery in Babol, northern Iran in 2007. Data were collected using a questionnaire, including birth intervals, demographics, fertility variables, such as maternal education, maternal age at birth, gender of index child, history of still births, child status (infant mortality or still birth) of index child, parity, duration of breast feeding, residence area, contraception method used, and attendance at a family planning clinic. The data were analyzed using a logistic regression model. The mean (+/- SD) birth interval was 61 +/- 25.7 months. In 3.8% of women the birth interval was < 2 years, in 41.7% it was 4-5 years and in 28% it was > or = 6 years. The majority of women (76.8%) were age 20-34 years old at the time of pregnancy. About one-fourth (22.4%) of women were > or = 35 years old at the time of pregnancy and 0.8% of women were < 20 years old at pregnancy. Maternal age, duration of breast feeding, sex of index child, history of still births, history of infant mortality of the index child, type of contraception used, regular attendance at a family planning clinics and parity showed a significant correlation with birth interval (p < 0.05).

Reducing stillbirths: behavioural and nutritional interventions before and during pregnancy

BACKGROUND

The vast majority of global stillbirths occur in low- and middle-income countries, and in many settings, the majority of stillbirths occur antenatally, prior to the onset of labour. Poor nutritional status, lack of antenatal care and a number of behaviours increase women's risk of stillbirth in many resource-poor settings. Interventions to reduce these risks could reduce the resulting burden of stillbirths, but the evidence for the impact of such interventions has not yet been comprehensively evaluated.

METHODS

This second paper of a systematic review of interventions that could plausibly impact stillbirth rates covers 12 different interventions relating to behavioural and socially mediated risk factors, including exposures to harmful practices and substances, antenatal care utilisation and quality, and maternal nutrition before and during pregnancy. The search strategy reviewed indexed medical journals on PubMed and the Cochrane Library. If any eligible randomised controlled trials were identified that were published after the most recent Cochrane review, they were added to generate new meta-analyses. Interventions covered in this paper have a focus on low- and middle-income countries, both because of the large burden of stillbirths and because of the high prevalence of risk factors including maternal malnutrition and harmful environmental exposures. The reviews and studies belonging to these interventions were graded and conclusions derived about the evidence of benefit of these interventions.

RESULTS

From a programmatic perspective, none of the interventions achieved clear evidence of benefit. Evidence for some socially mediated risk factors were identified, such as exposure to indoor air pollution and birth spacing, but still require the development of appropriate interventions. There is a need for additional studies on culturally appropriate behavioural interventions and clinical trials to increase smoking cessation and reduce exposure to smokeless tobacco. Balanced protein-energy supplementation was associated with reduced stillbirth rates, but larger well-designed trials are required to confirm findings. Peri-conceptional folic acid supplementation significantly reduces neural tube defects, yet no significant associated reductions in stillbirth rates have been documented. Evidence for other nutritional interventions including multiple micronutrient and Vitamin A supplementation is weak, suggesting the need for further research to assess potential of nutritional interventions to reduce stillbirths.

CONCLUSION

Antenatal care is widely used in low- and middle-income countries, and provides a natural facility-based contact through which to provide or educate about many of the interventions we reviewed. The impact of broader socially mediated behaviors, such as fertility decision-making, access to antenatal care, and maternal diet and exposures like tobacco and indoor air pollution during pregnancy, are poorly understood, and further research and appropriate interventions are needed to test the association of these behaviours with stillbirth outcomes. For most nutritional interventions, larger randomised controlled trials are needed which report stillbirths disaggregated from composite perinatal mortality. Many antepartum stillbirths are potentially preventable in low- and middle-income countries, particularly through dietary and environmental improvement, and through improving the quality of antenatal care - particularly including diagnosis and management of high-risk pregnancies - that pregnant women receive.

On the distribution of the menstruating interval

This article is concerned with the development of some stochastic models better suited to describe the observed distributions of the menstruating interval relating to last closed-birth interval of two types of females. In this context, two models suited for couples using or not using contraception have been proposed. In the first case, the model assumes a constant conception rate (analogous to the constant hazard rate in the life-testing problem) over time whereas the second case assumes a time-dependent form of the conception rate. The models have been applied to the data collected in a survey conducted in Lucknow, and estimates of conception rate for the two types of females have also been obtained.

Low birth weight as a risk factor for infant mortality in Egypt

We examined the risk of infant mortality among low-birth-weight children (< 2500 g) controlling for other risk factors of infant mortality. We used survival regression analysis on 11,361 childbirths in the 5 years preceding the 2000 Egypt Demographic and Health Survey. Higher birth order; shorter birth interval; lack of prenatal care, safe sources of drinking-water and hygienic toilet facilities; living in urban residence and Upper Egypt rural region were associated with a higher isk of infant mortality. The multivariate model indicated that low-birth-weight children were about 3 times more likely to die in infancy than other children (hazard ratio = 2.89, 95% CI: 2.33-3.58) independent of other risk factors.

Brothers and reduction of the birth weight of later-born siblings

It has been speculated whether maternal immune responses against male-specific minor histocompatibility (H-Y) antigens affect pregnancies negatively. This study explores, on a population level, whether previous births of boys compared with girls are associated with a decrease in birth weight of later-born siblings. The population was identified in the Danish Birth Registry and consisted of all Danish women who gave birth to their first-born singleton from 1980 to 1998. The women were followed until 2004, and their subsequent births were recorded. A total of 545,839 second- to fourth-born children were identified. The authors used linear regression to analyze the association between sex of preceding children and birth weight of subsequent siblings. Brothers compared with sisters reduced the birth weight of later-born siblings. One or two brothers, respectively, reduced the mean birth weight of later-born boys by 29 g (p = 0.0001) and 38 g (p = 0.0001) and later-born girls by 17 g (p = 0.0001) and 21 g (p = 0.0001) compared with later-born siblings with no brothers. Part of this association was due to a shorter gestation among later-born siblings with brothers. An explanation for these results could be maternal immune reactions directed against the H-Y antigens initiated during pregnancies with boys. The findings might add to the understanding of both normal and pathologic pregnancies.

Effects of interpregnancy interval and outcome of the preceding pregnancy on pregnancy outcomes in Matlab, Bangladesh

OBJECTIVE

To estimate the effects on pregnancy outcomes of the duration of the preceding interpregnancy interval (IPI) and type of pregnancy outcome that began the interval.

DESIGN

Observational population-based study.

SETTING

The Maternal Child Health-Family Planning (MCH-FP) area of Matlab, Bangladesh.

POPULATION

A total of 66,759 pregnancy outcomes that occurred between 1982 and 2002.

METHODS

Bivariate tabulations and multinomial logistic regression analysis.

MAIN OUTCOME MEASURES

Pregnancy outcomes (live birth, stillbirth, miscarriage [spontaneous fetal loss prior to 28 weeks], and induced abortion).

RESULTS

When socio-economic and demographic covariates are controlled, of the IPIs that began with a live birth, those < 6 months in duration were associated with a 7.5-fold increase in the odds of an induced abortion (95% CI 6.0-9.4), a 3.3-fold increase in the odds of a miscarriage (95% CI 2.8-3.9), and a 1.6-fold increase in the odds of a stillbirth (95% CI 1.2-2.1) compared with 27- to 50-month IPIs. IPIs of 6-14 months were associated with increased odds of induced abortion (2.0, 95% CI 1.5-2.6). IPIs > or = 75 months were associated with increased odds of all three types of non-live-birth (NLB) outcomes but were not as risky as very short intervals. IPIs that began with a NLB were generally more likely to end with the same type of NLB.

CONCLUSIONS

Women whose pregnancies are between 15 and 75 months after a preceding pregnancy outcome (regardless of its type) have a lower likelihood of fetal loss than those with shorter or longer IPIs. Those with a preceding NLB outcome deserve special attention in counselling and monitoring.

Birth interval: perceptions and practices among urban-based Saudi Arabian women

To determine perceptions towards birth spacing, actual birth interval and associated sociodemographic factors, we carried out a cross-sectional study on 436 mothers aged 15-50 years in Al-Khobar. All had had > or = 2 children within the previous 10 years. Only 5.2% preferred a birth interval of < 2 years, 28.2% preferred a 2 -< 3-year interval, while the rest favoured > or = 3 years. Education and employment status were predictors of birth spacing preference. About half were not aware of the physical benefits associated with longer birth interval. Only 26.3% had mean birth interval < 2 years. Age and employment status were significant positive predictors of longer birth interval. Oral contraception was the most popular method adopted for child spacing.

The associations between inter-pregnancy interval and maternal and neonatal outcomes in Brazil

OBJECTIVES

Global estimates of maternal and perinatal mortality have remained unchanged over the past 20 years, and strategies are being sought to decrease the occurrence of maternal and perinatal death. The objective of this study was to evaluate the association between inter-pregnancy interval and the occurrence of adverse maternal and perinatal outcomes.

METHODS

DESIGN AND SETTING

Cross-sectional study of the obstetrical and perinatal records in an intra-hospital obstetrics database between 1986 and 2000 at a tertiary maternity hospital in Brazil.

PARTICIPANTS

A total of 14,930 records of parous women who delivered singleton infants.

MAIN OUTCOME MEASURES

Crude and adjusted odds ratio estimates of gestational outcome according to inter-pregnancy intervals.

RESULTS

During the period of the study, 34.6% of records referred to women with an inter-pregnancy interval <18 months. After the adjustment performed for 11 confounding factors and assuming an inter-pregnancy interval of 18-23 months as reference, short intervals (<6 months) were observed to be associated with a greater risk of low birth weight (odds ratio: 1.74; 95% confidence interval: 1.18-2.55), and preterm birth (1.56; 1.01-2.46). On the other hand, long intervals were significantly associated with fewer C-sections (0.69; 0.56-0.82), and a greater risk of premature rupture of membranes (PROM) (1.57; 1.20-2.06) and low birth weight (1.46; 1.03-2.06).

CONCLUSIONS

Short inter-pregnancy intervals are associated with a higher risk of low birth weight and preterm birth, while long intervals are associated with a higher risk of PROM, low birth weight and a lower risk of C-section.

Short interpregnancy interval and risk of spontaneous preterm delivery

OBJECTIVES

Short interpregnancy intervals are related to increased prevalence of adverse perinatal outcomes. However, the reported association with preterm birth might be due to confounding by factors such as previous pregnancy outcomes, socioeconomic level or lifestyles. The objective of this study was to evaluate the effect of short interpregnancy interval on the occurrence of spontaneous preterm delivery.

STUDY DESIGN

The prevalence of a short interpregnancy interval, defined as six or less months between a preceding delivery or abortion and the last menstrual period before index pregnancy, was compared between 263 spontaneous preterm (<37 weeks) and 299 term (37-42 weeks) consecutive births. Separate analyses were performed for early (<34 weeks) and late (34-36 weeks) preterm deliveries. Crude and adjusted odds ratios (ORs) and 95% confidence intervals (CI) were calculated using unconditional logistic regression.

RESULTS

There was a significant association between short interpregnancy interval and spontaneous early preterm delivery, both crude (OR=3.9; 95% CI: 1.91-8.10) and adjusted for maternal age, school education, previous birth outcomes, antenatal care, smoking habits, body mass index and gestational weight gain (adj(OR)=3.6; 95% CI: 1.41-8.98). No significant effect on spontaneous late preterm delivery was found (crude(OR)=0.8; 95% CI: 0.32-1.83).

CONCLUSIONS

This study showed that short interpregnancy intervals significantly increased the risk of early spontaneous preterm birth but no such effect was evident for late preterm deliveries.

Differentials of post-partum amenorrhea: a survival analysis

Post-partum amenorrhea is an important event for females' reproductive life and their health. It is the time period between the end of pregnancy and the resumption of menstruation after delivery, and it is considered to be the temporary infecundable period of women's reproductive life-span. The main aim of this article is to examine the differentials of post-partum amenorrhea by using current status reporting data according to the characteristics of the mother and her child. The data are utilized from a sample survey of Palpa and Rupandehi districts of western rural Nepal. A life-table based technique of survival analysis has been used. Important summary measures have been computed in order to see the differentials of duration of post-partum amenorrhea. The study revealed that parity of mothers, age of mothers, breast-feeding practices and survival status of the child were found to be the main differentials of the duration of post-partum amenorrhea. Amenorrhea period was found shorter for lower parity and younger mothers. Amenorrheic period was found to be increased with increased birth-interval and duration of breast-feeding practices. A strong positive association was found between the duration of post-partum amenorrhea and breast-feeding. The study also revealed that an inverse association was found between the duration of post-partum amenorrhea and socio-economic status of mothers. The survival status of the child showed a strong effect for the timing of amenorrhea. This study investigated the important differentials of amenorrhea by using current status reporting data according to the characteristics of mother and her child. The estimated values of mean, median and trimean duration of amenorrhea were compared. For instance, trimean of amenorrheic period was found to be 9.6 months while median was 8.4 months and mean was 10.4 months. This finding indicates that the trimean provided the most consistent and best estimates of the duration of amenorrhea than other averages. The trimean is the best measure if the data contain censored and open-ended class interval. Parity, age of mothers, survival status of child, breast-feeding practices and socio-economic status of mothers were found to be the main influencing factors for the timing of amenorrhea among rural Nepalese mothers. Although the coverage of the present study is limited to small areas as well as to a small sample size, it is expected that the findings may help in designing appropriate policies and programs for improving mothers' and children's health as well as for reducing the existing fertility level of a country.

Marital decision-making and the timing of first birth in rural China before the 1990s

Using a sample of couples drawn from the three provinces of Guangdong, Shandong, and Shaanxi, we investigated whether couples' increasing freedom to choose whom to marry influenced the timing of first birth in rural China during the four decades before the 1990s. The shortening of first-birth intervals in the period is found to be associated with the shift from arranged to free-choice marriages. The association is attributed largely to increased intimacy and coital frequency after marriage together with postponement of age at first marriage.

[Short interpregnancy intervals: risk factors and perinatal outcomes]

OBJECTIVES

To study risk factors and perinatal outcomes in short interpregnancy intervals.

MATERIALS AND METHODS

Retrospective study, between 1995 and 2001, comparing women with short interpregnancy intervals (<6 months, n = 192) and women controls (interpregnancy intervals between 18 and 23 months, n = 210). The analysis included demographical and social factors, maternal medical histories and perinatal outcomes for the 2(nd) pregnancy.

RESULTS

Risk factors of short interpregnancy intervals were: young age, no anterior contraception, celibacy, medical history of intrauterine fetal death or medical pregnancy termination and high parity and gestity. The patients at risks of short interpregnancy intervals often belong to little supported social background, are generally without profession and often leave against medical opinion. The short interval between pregnancies is associated to a high score of prematurity (19% vs 8%, OR = 2.8, p < 0.001).

CONCLUSION

These data suggest that obstetricians and other care providers need to be alert to these identifiable risk factors and then direct preventive strategies during and after pregnancy.

The distribution of consecutive closed birth intervals in females in Uttar Pradesh

Most studies of closed birth intervals are regarding their variation at specific orders among females. This paper attempts to study the nature of the distributions of consecutive closed birth intervals. Data from the Uttar Pradesh National Family Health Survey 1998-99 (NFHS-2) were analysed. It was found that, under certain assumptions, the postpartum amenorrhoea period and menstruating interval are negatively associated, indicating that socio-cultural factors are affecting the menstruating interval.

[Effects of the late marriage of Korean women on the first-birth interval]

OBJECTIVES

The purpose of this study was to examine the effect of women's late age of marriage on the interval between marriage and their first birth.

METHODS

Data from Year 2000 Korea National Fertility Survey was collected through direct interview questionings, and the data was analyzed based on randomly selected sampling. In particular, the married women (N=5,648) were analyzed for the factors that determined the first-birth interval by performing Cox's proportional hazard model survival analysis.

RESULTS

Unlike previous findings, the woman whose age of marriage was 30 or more was more likely to delay the birth of her first baby than were the other women who married earlier. Further, a woman's age at marriage, a woman's residence before marriage, her husband's religion, her husband's level of education and the difference in age between the woman and her husband significantly influenced the first-birth interval. In contrast, for a married woman, her age, level of education, current residence and religion were not significant predictors of her first birth interval.

CONCLUSIONS

Our study showed that women who married at the age of 30 years or more tend to postpone their first birth in Korea. When facing the increasing number of women who marry at a late age, the Korean government should implement population and social policies to encourage married women have their first child as early as possible.

Primary mode of delivery and subsequent pregnancy

OBJECTIVE

To investigate the relationship between primary mode of delivery and subsequent pregnancy and to compare the findings with a previous study conducted on an earlier cohort from the same population.

DESIGN

Population cohort.

SETTING

Aberdeen City, Scotland.

POPULATION

Women who delivered their first singleton child in Aberdeen Maternity Hospital between 1980 and 1997.

METHODS

Population-based data relating to the index and next pregnancy event, if any, were obtained from the Aberdeen Maternity Neonatal Databank. Subsequent pregnancy was compared across the three modes of delivery groups using log rank tests and Cox proportional hazards regression models.

MAIN OUTCOME MEASURE

First subsequent pregnancy following index delivery.

RESULTS

Women who delivered by caesarean section (CS) were less likely to have a subsequent pregnancy compared with those who had a spontaneous vaginal delivery (SVD), hazard ratio = 0.91 (95% CI 0.87, 0.95). This confirmed the findings of a previous study conducted on an earlier cohort of the same population. The median time to next pregnancy following CS was 36.3 months, 31.8 months following instrumental vaginal delivery (IVD) and 30.4 months following SVD. In contrast to the earlier study where women who had an instrumental delivery were found to be an intermediate group, we found no difference in subsequent pregnancy following IVD compared with SVD, HR = 1.0 (95% CI 0.96, 1.03).

CONCLUSIONS

Following an initial delivery by CS, fewer women went on to have another pregnancy compared with SVD. The incidence of subsequent pregnancy is similar following instrumental and SVD.

Applying a data duplication technique in linear regression analysis of waiting time to pregnancy

This analysis demonstrates the application of a data duplication technique in linear regression with censored observations of the waiting time to third pregnancy ending in two outcome types, using data from Malaysia. The linear model not only confirmed the results obtained by the Cox proportional hazards model, but also identified two additional significant factors. The method provides a useful alternative when Cox proportionality assumption of the hazards is violated.

Duration and determinants of interbirth interval: community-based survey of women in southern Jordan

The duration and determinants of interbirth intervals among women of reproductive age in Karak, Jordan were examined in October 2003. A multistage sampling technique was used to select 1109 ever-married women aged 15-49 years who contributed to 4349 interbirth intervals. Data were obtained by interview questionnaire and analysed with life table, Kaplan-Meier survival and Cox regression analyses. The median interbirth interval was 27.40 months. Longer interbirth interval was independently predicted by breastfeeding > or = 12 months, modern contraceptive use and pregnancy wastage; by more surviving children, presence of boys only or both boys and girls at the interval onset; by woman's higher education, older age and longer marriage; and by ideal spacing conforming with family planning norms. Concerted efforts to encourage modern contraceptive use, extend breastfeeding, promote small family size, address gender preferences and reinforce the minimum age at marriage should be made.

The Relationship Between Birth Predictedness and Violence During Pregnancy Among Women in La Paz and El Alto, Bolivia

OBJECTIVES

The main objectives were to estimate the prevalence of predicted and unpredicted last births using a prospective approach and to estimate the prevalence of violence during the last pregnancy. In addition, the relationship between birth predictedness and violence during pregnancy was examined.

METHODS

The target population for this study was women who had participated in the 1994 Demographic and Health Survey (DHS) and lived in El Alto and La Paz Bolivia (n = 1308). In 1997, 816 women were located and re-interviewed. During this three-year interval, 127/816 women had given birth to their last child.

RESULTS

Of the last births that occurred during the three-year interval, 82% were unpredicted (18% were to women who stated in 1994 that they wanted to postpone childbirth for more than three years and 64% were to women who stated they wanted to wanted to forego childbearing entirely). Twenty-eight percent of women reported that they had experienced violence during their last pregnancy. No statistically significant relationship was found between birth predictedness and violence during their pregnancy.

CONCLUSIONS

The majority of births that occurred in the three-year study interval were unpredicted. The prevalence of violence during pregnancy was alarmingly high among this sample of women. Further investigation on violence during pregnancy is needed and should be expanded to examine how violence during pregnancy impacts maternal and infant outcomes, which have remained poor in this country. In addition, the high rates of unpredicted births illustrate that work remains to be done in addressing women's ability to control their fertility.

Infant mortality in Zambia: socioeconomic and demographic correlates

Trends in infant mortality in Zambia suggest a reversal of the decline experienced between the 1960s and the late 1970s. From a high of about 140, infant mortality rate declined to about 90 in the late 1970s only to rise again to 100 by 1996. Data on 5,600 births born between 1987 and 1992, and 6,630 births between 1991 and 1996 from the Zambian DHS are analyzed to identify socioeconomic and demographic correlates of infant mortality. Demographic factors such as small size at birth and short birth intervals are associated with higher neonatal mortality. In the post-neonatal period, urban children from poorer households had the highest mortality between 1991-1996. Also, differences in infant mortality rates between provinces narrowed. Children born in the most developed province of Lusaka had as high of risk of dying as those from Luapula, a province with a history of extremely high mortality rates in Zambia.

Effect of prolonged birth spacing on maternal and perinatal outcome

BACKGROUND

Researchers have held varied opinions on the effect of prolonged birth spacing on maternal and perinatal outcome.

OBJECTIVES

To determine the reasons for prolonged birth spacing and to compare the maternal and perinatal outcome compared to shorter normal birth spacing.

DESIGN

Comparative case - controlled study between January 1st, 2001 to December 31st, 2002.

SETTING

Obstetric Unit of Obafemi Awolowo University Teaching Hospital Complex, Ile-Ife, Nigeria.

SUBJECTS

Fifty cases consisted of multiparae with prolonged birth spacing (> or =6 years) and controls consists of similar number of multiparae with shorter normal birth spacing (2 - 5 years) matched for age, parity and socio-economic status.

MAIN OUTCOME MEASURES

Labour outcome, Apgar scores, operative and vaginal delivery rates, perinatal and maternal outcome, reasons for prolonged birth spacing.

RESULTS

There was no significant difference observed with respect to spontaneous onset of labour, induction or argumentation of labour, duration of labour, spontaneous vaginal delivery rates, Caesarean section rates, instrumental vaginal deliveries, analgesic requirement, postpartum haemorrhage, and Apgar scores in both groups. There were no perinatal or maternal deaths. The commonest reason adduced for prolonged birth spacing is failed contraception (56%), followed by secondary infertility (24%) and to a lesser extent re-marriage, improved income and sheer desire.

CONCLUSION

There was no significant difference in maternal and perinatal outcome in pregnancy between women with prolonged birth spacing and those with normal shorter birth spacing.

Household crowding index: a correlate of socioeconomic status and inter-pregnancy spacing in an urban setting

OBJECTIVES

This paper examines the effect of household crowding on inter-pregnancy spacing and its association with socioeconomic indicators, among parous mothers delivered in an urban environment.

DESIGN

Cross sectional survey.

METHODS

Sociodemographic data were obtained on 2466 parous women delivering at eight hospitals in Greater Beirut over a one year period. Statistical methodology comprised Pearson chi(2) test and logistic regression analysis.

MAIN RESULTS

A significant inverse relation was observed between household crowding and socioeconomic status, defined as education and occupation of women and their spouses. Inter-pregnancy spacing increased with higher levels of crowding. Further analysis suggested that this positive association was confounded by maternal demographic characteristics.

CONCLUSIONS

These data have shown that household crowding, a correlate of low parental socioeconomic status, is associated with longer birth intervals. This association, however, seems to be largely explained by maternal age and parity.

Reproductive parameters and life-history variables in captive golden-bellied mangabeys (Cercocebus agilis chrysogaster)

An understanding of the reproductive physiology of captive primates is vital for their successful management. We report on reproductive parameters and life-history variables collected at the Sacramento Zoo for five female golden-bellied mangabeys (Cercocebus agilis chrysogaster) over a 7-year period. For each female, we collected data on their sexual skins, menses, gestation, and other pregnancy-related factors, such as postconception bleeding and swelling. We used these data to estimate life-history variables, such as age at onset of estrus, menses, and conception, as well as the duration of intervals between births, and between parturition and the resumption of cycling. Cercocebus agilis chrysogaster is comparable to other Cercocebus species in terms of reproductive parameters, although variability is exhibited within and among female subjects. In some cases, it appears that stressful incidents altered cycle length or halted cycling altogether. We suggest the use of husbandry practices that include consistent data collection to enhance regularity in reproductive cycles, and maximize captive breeding success for this rare species.

Association between short birth intervals and schizophrenia in the offspring

Pregnancy burdens maternal folate reserves. Postpartum restoration to normal folate values may take up to 1 year. Maternal folate deficiency during early pregnancy has been hypothesized as a cause of schizophrenia in the offspring. We investigated whether the risk of schizophrenia is increased in persons conceived shortly after another birth. A population-based cohort was established of 1.43 million persons born in Denmark between 1950 and 1983, yielding 17.6 million person-years of follow-up. Schizophrenia in cohort members (5095 cases) and their siblings and parents was identified by linkage with the Danish Psychiatric Case Register. Relative risks of schizophrenia were estimated by use of log-linear Poisson regression. As compared to intervals of 45 months and longer, the schizophrenia risk ratio was 1.14 (95% confidence interval [CI], 0.97 to 1.35) for interbirth intervals of up to 15 months, 1.32 (95% CI, 1.12 to 1.56) for intervals of 15 to 17 months, 1.38 (95% CI, 1.18 to 1.61), for intervals of 18 to 20 months and 1.13 (95% CI, 1.00 to 1.29) for intervals of 21 to 26 months. Relative risks did not essentially change after adjustment for age, sex, calendar year of diagnosis, maternal and paternal age, history of mental illness in a parent or sibling, sibship size, place of birth, and distance to younger sibling. These results show an association between short birth intervals and schizophrenia in the offspring. Although maternal folate depletion may play a role in this association, we cannot rule out other explanations such as maternal stress during pregnancy and childhood infections.

Effect of interpregnancy interval on infant low birth weight: a retrospective cohort study using the Michigan Maternally Linked Birth Database

OBJECTIVE

To examine the relationship between interpregnancy interval and low birth weight (LBW), using the retrospective cohort design.

METHODS

We used the maternally linked Michigan livebirth data documented between 1989 and 2000 to evaluate LBW in relation to interpregnancy (i.e., delivery-to-conception) interval, overall and at levels of other reproductive risk factors. We fit separate logistic regression models for pairs of first-second, second-third, third-fourth, and fourth-fifth births to control for confounding.

RESULTS

Of the 565,911 infants identified, 5.5% had LBW. Univariate and stratified analyses showed that the risk for LBW was lowest when the interpregnancy interval was 18-23 months, and increased with shorter or longer intervals. This J-shaped relationship persisted after controlling for all risk factors simultaneously. For example, among the first-second birth pairs, the adjusted odds ratios (AORs) for LBW associated with interpregnancy intervals <6, 24-59, 60-95, and 96-136 months were 1.4 (95% confidence interval [CI] = 1.3-1.5), 1.5 (95% CI = 1.3-1.6), 1.1 (95% CI = 1.0-1.1) and 1.5 (95% CI = 1.3-1.8), respectively, compared with an interval of 18-23 months. Among the second-third birth pairs, the AORs were 1.5 (95% CI = 1.3-1.6), 1.3 (95% CI = 1.2-1.4), 1.1 (95% CI = 1.0-1.1), and 1.6 (95% CI = 1.3-2.0), respectively. Among the third-fourth birth pairs, the AORs were 1.2 (95% CI = 1.1-1.4), 1.3 (95% CI = 1.1-1.5), 1.0 (95% CI = 0.9-1.1), and 1.4 (95% CI = 1.0-2.0), respectively. Among the fourth-fifth birth pairs, the AORs were 1.3 (95% CI = 1.1-1.6), 1.2 (95% CI = 0.9-1.5), 1.1 (95% CI = 1.0-1.4), and 1.3 (95% CI = 0.8-2.3), respectively. The population attributable risk associated with interpregnancy intervals shorter than 18 months or longer than 23 months was 9.4%.

CONCLUSION

These data suggest that spacing pregnancies appropriately could be used as a strategy for preventing LBW.

Breastfeeding indicators in Dakahlia governorate

This study was carried out in Dakahlia Governorate to assess current breastfeeding practices using the standardized breastfeeding indicators developed by the World Health Organization and to highlight the impact of some socioeconomic and maternal factors on these indicators. An interview was carried out with mothers of 1200 infants and children < 24 months during a poliomyelitis immunization campaign in urban and rural areas. The findings indicate that 84.6% of infants aged 0-4 months are fully breastfed, with 42.5% and 42.1% of them exclusively and predominantly breastfed respectively. Rural infants are more likely to be exclusively breastfed, to continue breastfeeding for 1 year and to initiate breastfeeding early. Non-working mothers are more likely to breastfeed exclusively and more likely to continue breastfeeding for 1 year.

Emergent properties in small-scale societies

A multi-agent simulation is used to explore the relationship between the micro and the macro levels in small-scale societies. The simulation demonstrates, using an African hunter-gatherer group (the !Kung san) as a case study, the way in which population stability may arise from culturally framed, micro-level decision making by women about spacing of births. According to the simulation, population stability as an emergent property has different implications, depending on resource density. Data on Australian hunter-gatherer groups are presented that support the implications of the simulation. !Kung san micro-level cultural rules on incestuous marriages are shown to have macro-level consequences in the form of marriages between residential camps. Between-camp marriages have significant implications for access to resources and thereby for population dynamics of the group as a whole.