Latina mothers in the United States enjoy surprisingly favorable birth outcomes despite their social disadvantages. This "Latina paradox" is particularly evident among Mexican-born women. The social and cultural factors that contribute to this paradox are maintained by community networks--informal systems of prenatal care that are composed of family, friends, community members, and lay health workers. This informal system confers protective factors that provide a behavioral context for healthy births. US-born Latinas are losing this protection, although it could be maintained with the support of community-based informal care systems. We recommend steps to harness the benefits of informal systems of prenatal care in Latino communities to meet the increasing needs of pregnant Latina women.