For decades, the majority of Americans have reported ideal family sizes of two children, yet actual birth rates are falling well below reported ideals. Julia Behrman, Emily Marshall, and Florian Keusch’s survey experiment shows that once competing work, financial, and family demands are taken into account, a two-child family is not a strong preference for young American women.
For more than 50 years, people in the U.S. have reported that their ideal family size is about 2.5 children (Behrman 2024; Hagewen and Morgan 2005). The large share of Americans reporting ideal family sizes of two children points to the persistence of a widespread “two-child norm” in American family life. Yet, since 2010, the average number of children born per woman in the U.S. has dropped below two and the decline is ongoing (Osterman et al. 2025).
The persistence and puzzle of the two-child norm
This gap between the number of children Americans say is ideal and the number of children they have is puzzling. For decades, the U.S. showed close alignment between ideal family size and actual fertility, unlike many European countries where this gap has been long-standing (Hagewen and Morgan 2005). The growing disconnect between ideal family size and actual childbearing raises questions about the strength of the two-child norm in the contemporary U.S.
Standard surveys ask people about their ideal family size without considering the complex realities of life today. Factors like financial stress, work demands, partnership status, and caregiving responsibilities can influence whether having two children is truly a top priority. To understand how strong preferences for two children really are, we need to look at the choices people make when juggling multiple competing demands.
Measuring the strength of preference for two children
We conducted a nationally representative online survey of 1,785 American women of childbearing ages (18-35) using a method called a “conjoint survey experiment” (Behrman, Marshall, and Keusch 2025). Instead of asking for a single ideal number of children, this method presents participants with different family scenarios that vary in terms of number of children and other life factors such as financial status, relationship status, work hours, family policies and so on. Respondents choose which scenario they prefer, revealing the importance of each factor when forced to make trade-offs.
This approach lets us answer two key questions:
1) Do young women prefer two children when considering other family, financial, and work demands?
2) How does preference for two children compare to preference for other factors of family life such as relationship status or financial stability?
Our study found that preference for two children was not significantly stronger than preference for zero, one, or three children when competing work, financial, and family demands were taken into account (Figure 1). However, women clearly preferred families with two children over those with four, thus suggesting preference away from very large families.
We also found that factors such as relationship status, financial security, work hours, and the availability of family-friendly policies had a stronger influence on family preferences than the number of children. For example, being married (rather than single or living with someone) and having enough money to pay household bills (rather than financially struggling) mattered more for family preferences than whether the family had two children. These results indicate that preference for two children is weak compared to preferences about other dimensions of family life.
Interestingly, younger women aged 18 to 25 showed a notably higher preference for having no children compared to older women in the sample (Figure 2). This could be because childbearing is less central to the life goals of young Americans. Other studies support this, showing that young adults often place more importance on career fulfillment and social relationships than on having children (Parker and Minkin 2023). Alternatively, this finding could be driven by the younger ages of these respondents who may change their minds about childbearing as they grow older and consider starting families more seriously.
What does this mean for U.S. fertility?
Our results help make sense of why U.S. fertility rates are falling even though the two-child ideal remains common in surveys. They indicate that having two children is not a strong preference for many young American women when faced with competing work, family, and financial pressures. Instead, preferences for family size appear less important than other life priorities such as achieving financial stability or finding a long-term partner. While the two-child norm may remain an important cultural reference point, achieving the two-child ideal does not appear to be one of the highest priorities for many American women of reproductive ages.
References
Behrman, Julia A. 2024. “Ideal Family Size and Reproductive Orientations: An Exploration of Change Over Time in the United States.” Demography 61(5):1535–57. doi:10.1215/00703370-11577510.
Behrman, Julia, Emily A. Marshall, and Florian Keusch. 2025. “An Experimental Approach to Assessing Young Women’s Childbearing Preferences: A Research Note on the United States.” Demography 11962185. doi:10.1215/00703370-11962185.
Hagewen, Kellie J., and S. Philip Morgan. 2005. “Intended and Ideal Family Size in the United States, 1970-2002.” Population and Development Review 31(3):507–27. doi:10.1111/j.1728-4457.2005.00081.x.
Osterman, M. J. K., B. E. Hamilton, J. A. Martin, A. K. Driscoll, and C. P. Valenzuela. 2025. Births: Final Data for 2023. vol 74, no 1. Hyattsville, MD: National Center for Health Statistics.
Parker, Kim, and Rachel Minkin. 2023.“What Makes for a Fulfilling Life?” .