Before there is a childcare problem or an infertility problem, two people generally have to meet, choose one another, and build a life in which a child belongs. When that process begins later, takes longer, or never reaches a durable commitment, births disappear before anyone has made a decision about family size.
Consider one documented pattern without turning it into an invented person. In the United States, the median age at first marriage in 2025 was 30.8 for men and 28.4 for women. Fifty years earlier it was 23.5 and 21.1. A couple marrying at the newer median has not necessarily rejected children. Both may have spent their twenties doing what adulthood now asks: finishing school, establishing work, moving toward opportunity, and searching carefully for a partner. They begin the same hoped-for family with seven fewer years behind the wedding.
The gain is real. Later marriage can mean less pressure to accept a bad match, greater financial independence, and more freedom to leave danger or mistreatment. The demographic effect does not require those gains to be mistakes. It begins with time.
Marriage moved later Median age at first marriage in the United States. The postwar dip reversed after 1970, moving commitment deeper into the years when couples who want several children have less room for delay. Via Wikimedia Commons
Marriage is not the same demographic institution everywhere
Marriage statistics cannot be read alone. In the European Union, 41 percent of births occurred outside marriage in 2024, ranging from 10 percent in Greece to 62 percent in Bulgaria. Cohabiting unions carry much of the childbearing that marriage once contained in parts of Europe. A falling marriage rate there does not translate mechanically into the same fall in births.
Korea and Japan sit near the other end of the comparison. In the OECD’s 2020 data, fewer than 3 percent of births in each country occurred outside marriage. Where sex, household formation, and childbearing remain strongly organized around marriage, fewer marriages close one of the main routes to parenthood. The same change in legal marital status can therefore have a different demographic effect in France, the United States, and Japan.
The relevant question is not only whether a certificate exists. It is whether adults form a union stable enough to carry pregnancy, care, and the prospect of another child. Cohabiting couples can share affection, sacrifice, property, and years of life. Some intend permanence; others understand the household as provisional. Those differences matter more than a label alone, but they are harder to measure.
In the United States, roughly half of first births reported in the 2015–2019 National Survey of Family Growth occurred before marriage, and about half of those premarital births occurred within cohabiting unions. That is not a story of childbearing simply moving outside relationships. It is a story of family formation occurring through unions with different expectations and degrees of stability.
The partnership market
A person can want marriage and children and still fail to find someone suitable who wants the same life at the same time. The failure is experienced privately: another relationship that almost became serious, another year in which marriage remained plausible enough not to feel urgent.
Employment matters, especially for men. A national study of sexual activity found that young American men with lower income or part-time or no employment were more likely to report no sexual activity. That association does not prove that a job would produce a marriage. It does show that economic readiness and relationship formation are not separate worlds. Weak employment can delay a man’s willingness to commit while also making him a less attractive prospective husband.
Education has changed the pool as well. Women now earn more university degrees than men in many wealthy societies while people still tend to partner with someone of similar education. The result is not a simple shortage of men or women. It is a problem of matching expectations, location, education, work, age, and willingness to commit at the same moment.
Digital courtship changes how that matching occurs; a later section will examine the evidence. The partnership result belongs here. A larger visible pool does not guarantee a durable union, and more choice can coexist with more adults who remain unpartnered through their prime family-forming years.
What marriage adds
I think marriage matters for reasons larger than its correlation with births. It asks a man and woman to make their relationship public and durable, to accept obligations that survive changes in mood, and to form a household open to children and connected to kin across generations. The promise can be broken. Marriage can be unsafe, unequal, or unavailable, and no ceremony guarantees a good home. Its failures do not make the promise meaningless.
A child enters a web of claims that the child did not negotiate. Parents owe care; relatives acquire relationships; each spouse has reason to expect the other to remain when family life becomes inconvenient. Marriage gives that web a recognized center. It is more than official approval of a romance because it changes what the adults owe one another and what others may reasonably expect from them.
That institutional claim should not be confused with a claim that every unmarried person lacks commitment or that every marriage should have children. It explains why societies in which durable union becomes later, rarer, or more fragile can experience fewer births even when many individuals remain positively disposed toward family life.
The first threshold is therefore not the price of a crib. It is whether two people find one another and make a common future definite enough for a child to enter it.
Citations
- U.S. Census Bureau, “Census Bureau Releases New Estimates on America’s Families and Living Arrangements”, November 2025.
- Eurostat, Demography of Europe—2026 Edition, 2026.
- Organisation for Economic Co-operation and Development, Society at a Glance 2024, 2024.
- Kimberly Daniels and others, Fertility of Men and Women Aged 15–49 in the United States: National Survey of Family Growth, 2015–2019, National Center for Health Statistics, 2023.
- Peter Ueda and others, “Trends in Frequency of Sexual Activity and Number of Sexual Partners Among Adults Aged 18 to 44 Years in the US, 2000–2018”, JAMA Network Open 3, no. 6, 2020.