Friday, July 27, 2018

birth intervals and human bodies

In a study recently published in the journal Demography , my co-author Martin Kolk and I examined whether the length of the interval between births in Sweden is related to long-term health outcomes. The goal of our study was to examine whether the degree of spacing between births had any long-term consequences for the health of either the older or younger child. This study was a follow-up to a paper published in Demography last year where we examined whether birth spacing was associated with a series of cognitive, educational, and labour market outcomes, which we also summarized for N-IUSSP.

In our more recent study we examined whether birth spacing is associated with height, physical fitness, or the risk of being either overweight or underweight in early adulthood, as well as mortality in later adulthood. Research on the potential long-term health consequences of particularly short or long birth intervals is scarce – we were only able to identify a tiny handful of previous studies, some examining the relationship between birth intervals and mental health outcomes, and one examining the association with adult mortality in historical China.

Given that a large body of research has shown that birth intervals are associated with poor perinatal outcomes such as preterm birth and low birth weight, and those poor birth outcomes are also associated with poor long-term health, we had good reason to suspect that birth intervals shorter than 2 years or longer than 5 years might be associated with poor long-term health. Based on previous work we suspected that short intervals could have particularly negative consequences for the younger of any pair of siblings as the mother may not have been able to physically recover adequately from the previous pregnancy. Very short birth intervals also imply that the older child of the sibling pair was not breastfed, or only for a short time, since breastfeeding greatly reduces the mother’s likelihood of becoming pregnant again (lactational amenorrhea). The health benefits of breastfeeding are well known.

Furthermore, having closely spaced siblings might also affect the degree of parental attention, supervision, and investment in each child. For example, less parental attention and supervision might increase the risk of a child having a poor diet, developing unhealthy habits, and being at risk of accidents.
text is here

No comments: