Month of birth, twins survival and neonatal mortality

We examined the Demographic and Health Surveys (DHS) data from 31 countries over the last 20 years to estimate the levels and trends of first-day mortality rates considering potential differences in socioeconomic and healthcare factors. The trends in first-day mortality rates and 95% confidence intervals were estimated adjusting for potential clustering effects, comparing three successive DHS held across countries covering sub-Saharan Africa, South and Southeast Asia and Latin America. The findings show that first-day mortality rates varied widely from 21 deaths per 1000 live births in Mali and Ethiopia to about 17 per 1000 in Kenya and Nepal to less than 10 per 1000 in Dominican Republic, Philippines, Jordan and Egypt. The absolute change in the rates between DHS2 and DHS3 were not significant in about 24 countries and the levels were stagnantly high or increased in about 8 countries. First-day mortality increased consistently in Zimbabwe, Zambia, Senegal, Cambodia and Philippines. A negative linear relationship was found between skilled birth attendance, per-capita income and first-day mortality rates whereas a negative curvilinear relationship was observed between years of maternal schooling and first-day mortality rates. In countries where there is high medical intervention in births had relatively low first-day mortality.

Sub-Saharan Africa has the highest levels of both twining and under-five mortality in the world. It also had high excess mortality among twins. Surprisingly little is known about the infant and child mortality pattern among African twins. We examine which factors are associated with excess twin mortality and to what extent these factors are ‘universal’ or vary in weight by regions in Sub-Saharan Africa. We pool over 60 Demographic and Health Surveys from 32 Sub-Saharan African countries to obtain data on more than 45,000 twins. We include factors associated with under-five mortality on the child, mother and household level (e.g. maternal age & education, birth-interval) and the regional and national level (e.g. health-care facilities and development). We examine differences in these factors between twins and singletons and test interaction-effects between each determinant of mortality and twin/singleton status. Finally, we examine variations in the determinants across regions of Sub-Saharan Africa.

Under-five mortality rates (U5MR) have been declining slowly in Sub-Saharan Africa: between 1990 and 2008 the U5MR declined by only 22%. If there is a strong relationship between birth month and U5MR, then policies that help women conceive during optimal periods or that improve the health of pregnant women may help reduce U5MR. But the effectiveness of such policies will depend on whether the birth month effects are the result of structural differences in fertility patterns, or due to differences in pre and post-natal environments.
We use piecewise exponential hazard models to analyze the relationship between birth month and U5MR, in 30 SSA countries using data from the Demographic and Health Surveys. We also use logistic regression models to analyze the relationship between birth month and stunting.
The birth month effects on child mortality and stunting are large and statistically significant. On average, the U5MR associated with the birth month with the highest cumulative hazard is 39% higher than the U5MR for the birth month with lowest cumulative hazard. The maximum difference in predicted probabilities of being stunted between two birth months is on average nine percentage points. The birth month effects are not due to social-demographic differences in fertility patterns.

Reducing neonatal mortality is a particularly important issue in Bangladesh. We employ a competing risks model incorporating both observed and unobserved heterogeneity and allowing the heterogeneity terms for various causes to be correlated. Data come from the Health and Demographic Surveillance System (HDSS), Matlab.
Results confirm the general conclusion on levels, trends and patterns of causes of neonatal deaths in the existing literature, but also reveal some remarkable socioeconomic differences in the risks of cause-specific deaths. A remarkable finding is gender inequality in deaths particularly due to CDs in the icddr,b area which is about 70% higher for a boy than for a girl and this difference is aabout 11 deaths per 1,000 live births over the neonatal period.
Deaths due to low birth weight and other causes (sudden infant death, unspecified or specified) are better explained from the socio- economic covariates than deaths due to neonatal infections or obstetric complications.
The analysis highlights the role of maternal and child health interventions (particularly tetanus toxoid immunization for pregnant women, nutrition programs, and high coverage health services: distance to nearest health centre). Policies that increase quality and equity in child births may help to further reduce neonatal mortality.