Cools Sara, Kaldager Hart Rannveig
Institute for Social Research, Oslo, Norway.
Department of Sociology and Human Geography, University of Oslo, Oslo, Norway.
Demography. 2017 Feb;54(1):23-44. doi: 10.1007/s13524-016-0537-z.
Although fertility is positively correlated across generations, the causal effect of children's experience with larger sibships on their own fertility in adulthood is poorly understood. With the sex composition of the two firstborn children as an instrumental variable, we estimate the effect of sibship size on adult fertility using high-quality data from Norwegian administrative registers. Our study sample is all firstborns or second-borns during the 1960s in Norwegian families with at least two children (approximately 110,000 men and 104,000 women). An additional sibling has a positive effect on male fertility, mainly causing them to have three children themselves, but has a negative effect on female fertility at the same margin. Investigation into mediators reveals that mothers of girls shift relatively less time from market to family work when an additional child is born. We speculate that this scarcity in parents' time makes girls aware of the strains of life in large families, leading them to limit their own number of children in adulthood.
尽管生育能力在代际间呈正相关，但对于孩子在兄弟姐妹较多的家庭环境中的成长经历对其成年后生育能力的因果影响，我们却知之甚少。我们以头两个孩子的性别构成作为工具变量，利用挪威行政登记处的高质量数据，估算了家庭规模对成年生育能力的影响。我们的研究样本是20世纪60年代挪威家庭中至少有两个孩子的头胎或二胎（约110,000名男性和104,000名女性）。多一个兄弟姐妹对男性生育能力有积极影响，主要促使他们自己生育三个孩子，但在同等程度上对女性生育能力有负面影响。对中介因素的调查显示，女孩出生时，母亲从市场工作转向家庭工作的时间相对较少。我们推测，父母时间的这种稀缺使女孩意识到大家庭生活的压力，从而导致她们在成年后限制自己的生育数量。
