The United States has the world's highest share of children living in single-parent families. It has another distinction, too.
From OECD:
On average across OECD countries, mothers are entitled to just over 18 weeks of paid maternity leave around childbirth (Table PF2.1.A and Chart PF2.1.A). In line with both the ILO convention on maternity leave and the current EU directive on maternity leave, almost all OECD countries provide mothers with at least 14 weeks leave around childbirth; the main exception is the United States, which is the only OECD country to offer no statutory entitlement to paid leave on a national basis. In some countries, entitlements to paid maternity leave extend to over six months. In the United Kingdom, for example, mothers can take up to nine months paid maternity leave. Maternity leaves are generally well paid (Table PF2.1.A and Chart PF2.1.A). The majority OECD countries provide payments that replace over 50% of previous earnings, with 13 OECD countries offering a mother on average earnings full compensation across maternity leave. Payment rates are lowest in Ireland and the United Kingdom, where less than one-third of gross average earnings are replaced by the maternity benefit. As a result, despite lengthy maternity leave entitlements, full-rate equivalent paid maternity leave in these countries lasts only seven and twelve weeks, respectively.
