Abstract
It has been discussed in the literature that the presence of kin, particularly the presence of a women's own mother or her mother in law, may have fertility effects. We aimed to examine the effects of the presence of a woman's own or her husband's mother in the household on a woman's fertility in terms of number of children on a broad basis by analysing census data of over two million married women aged between 15 and 34 years from 14 countries worldwide. We find that with the exception of Iraq, across all countries, the majority of women live only with their spouse in the household. We further find that the presence of any mother in the household is invariably associated with a significantly lower number of children compared to women living only with their spouse. In addition, in most countries, a woman's number of children is lower if she lives with her own mother as compared to her husband's mother in the household. Number of children is nonlinearly associated with woman's age, the presence of any mother being related with an earlier start of childbearing but a shallower increase in number of children. We speculate that the presence of a mother in the household may slow down woman's reproduction, but also discuss alternative explanations.
Highlights
In humans, the long period of dependency of children, the simultaneous rearing of children and the short intervals between births mean a high demand of time and energy2017 The Authors
We find that regardless of statistical model, the absence of any mother in the household has a significant positive effect on a woman’s number of children: in all models, women living without any mother in the household have significantly more children than those living with their own mother, and—as indicated by lower estimates— more children than those living with their husband’s mother in the household
In the case that a mother is present in the household, it is less clear whether a woman has more children if this is her own or her husband’s mother: signs and significances vary both among differently complex models as well as among different countries
Summary
The long period of dependency of children, the simultaneous rearing of children and the short intervals between births mean a high demand of time and energy2017 The Authors. It is widely agreed that help for the mother increases her reproductive output and the survival of her children [2]. Hrdy [3,4] formulated the cooperative breeding hypothesis: mothers have evolved in groups where the biological father but a variety of individuals provided resources for the children. According to Hamilton’s rule, these support-providing individuals are expected to be close kin [3,5,6] who can increase their indirect biological fitness by helping their kin to reproduce. In particular grandparents in their postreproductive period may take the chance to increase indirect fitness by helping their own offspring to reproduce and investing in their grandchildren [7], with whom they are genetically related to an average 25%. In addition to promoting grandchildren survival, grandparents foster infant mental development [8] and are protective for their grandchildren (rev. in [9]) data from Switzerland show that the investment of grandparents seems to decrease with increasing number of grandchildren [10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
