Search

Most studies on birth intervals and infant mortality ignore pregnancies that do not result in live births. Yet, fetal deaths are important in infant mortality analyses for three reasons: ignoring fetal deaths between two live births lengthens the measured interval between births, implying that short intervals are underestimated; the recommended inter-pregnancy interval (IPI) after a fetal loss is shorter (6 months) than after a live birth (24 months), as the effect of IPI on outcomes might differ according to the previous type of pregnancy outcome; fetal death will selectively reduce the population at risk of neonatal mortality, leading to biased results. This study uses the Heckman selection model to simultaneously estimate the combined effect of IPI duration and the type of pregnancy outcome at the start of the interval on pregnancy survival and neonatal mortality. The analysis is based on retrospective data from the Rwanda Demographic Health Surveys of 2000, 2005 and 2010. The results show a significant selection effect. After controlling for the selection bias, short (<6 months) and long (>60 months) intervals after a fetal death reduce the chances of pregnancy survival, but no longer have an effect on neonatal mortality. For intervals starting with a live birth, the reverse is true. Short intervals (<24 months) do not affect pregnancy survival but increase the odds of neonatal mortality. If the previous child died in infancy, the highest odds are found for neonatal death regardless of the IPI duration. [ABSTRACT FROM PUBLISHER]

The consequences of different birth intervals on dietary energy requirements and dependency ratios at different stages of the family lifecycle are modelled for Gambian agriculturalists and !Kung hunter-gatherers. Energy requirements reach a peak at between 20 and 30 years after starting a family for the Gambians, and between 15 and 20 years for the !Kung. For the Gambians, shorter birth interval confers no economic advantage over the traditional birth interval of 30 months. For the !Kung, the lack of participation in subsistence activities by children gives an output:input ratio in excess of that reported in other studies, suggesting that they are in a state of chronic energy deficiency. [ABSTRACT FROM AUTHOR]