The Impact of Women’s Education on the Second Childbirth Interval: Evidence from the 2018 China Migrants Dynamic Survey

Within the significant global fertility rate decline, China’s negative population growth is particularly remarkable. Over 40 years, China has experienced two notable socioeconomic trends: longer birth intervals among women and improved educational levels. Investigating the relationship between these factors will enhance understanding of China’s current challenges and provide essential insights for global population governance. This study aimed to explore the effect and mechanism of women’s education level on the birth interval between first and second childbirths using a Cox regression model and data from the 2018 China Migrants Dynamic Survey. The results showed that: (1) Higher education levels significantly extended the interval before having a second child and reduced the probability of having a second child by 28.5%, while women with residential area-related above-average years of education also significantly delayed having a second child, reducing their likelihood by 20.5%. (2) The income substitution effect significantly moderated the influence of women’s education on the second childbirth interval, with higher income amplifying the impact of education, which further reduced the likelihood of women with higher education or residential areas with above-average years of schooling having a second child, thus extending the interval between births. And (3) The child penalty effect significantly moderated the influence of women’s education on the interval between childbirths. Increased work commitment and more severe penalties for childbearing enhanced the impact of women’s education on the birth interval, reducing the likelihood of having a second child for highly educated women and further prolonging the interval between births.