The impact of kin on female fertility: a systematic review

Rebecca Sear, London School of Economics and Political Science (LSE)
Paul Mathews, London School of Economics and Political Science (LSE)

Fertility decline is still a puzzle. A recent body of work has suggested that changes in kin networks may help explain changing reproductive behaviour. As countries modernise, kin networks break down and association with non-relatives becomes more common. This reduces both the practical support available to mothers in raising children, and affects reproductive norms. A previous review demonstrated that kin, particularly maternal kin, clearly have a beneficial impact on one aspect of female reproductive behaviour: the survival of her children. This paper presents the results of a systematic review of all studies which have investigated the impact of kin on female fertility: including age at first birth, length of birth intervals, total fertility and fertility preferences. Systematic reviews have been developed to introduce rigour into the review process with the aim of making reviews transparent and replicable. The results of this review supports the hypothesis that kin are important for fertility behaviour, since the presence of kin frequently, though not universally, influences fertility. The precise effects of kin vary between categories of kin and between different environments, however. A woman’s parents-in-law tend to speed up her reproductive output; whereas a woman’s own parents are about equally likely to speed up and slow down her reproduction. For example, the presence of a woman’s father is protective against very early childbearing (teenage pregnancy) in developed countries, but tends to result in earlier first births in developing country contexts. This review confirms that kin matter for female fertility behaviour, but that the precise nature of this influence is variable. Broadly speaking, however, the presence of kin is more likely to promote than restrict childbearing, suggesting that the loosening of kin ties associated with modernisation may be a plausible explanatory factor in the fertility decline.