CONTEXT: Studies published to date provide mixed evidence on the relationship between unintended pregnancy and preterm birth, and none take into consideration that the meaning of unintended pregnancy may vary across racial and ethnic groups.

METHODS: Data from the 1999–2003 rounds of the Maternal and Infant Health Assessment, a population-based, representative survey of postpartum women in California, were used to assess the relationship between pregnancy intention and preterm birth. For racial and ethnic groups in which an association was found, sequential logistic regression was conducted to further examine the relationship while controlling for socioeconomic characteristics.

RESULTS: In unadjusted results, pregnancy intention was associated with preterm birth among both whites and immigrant Latinas, but not among blacks or U.S.-born Latinas. Among whites, compared with women who reported that their pregnancy was intended, those who were unsure about their pregnancy had elevated odds of preterm birth (odds ratio, 1.4), as did those who reported their pregnancy was unwanted (1.7) or mistimed (1.4). Among immigrant Latinas, those who reported being unsure about their pregnancy were at higher risk of preterm birth than were those who reported an intended pregnancy (1.6). After adjustment for socioeconomic factors, the association remained significant for immigrant Latinas who were unsure about their pregnancy (1.5), but none of the associations remained significant for whites.

CONCLUSIONS: Women’s interpretations of questions about pregnancy intention and their social experiences regarding pregnancy intention may vary by race or ethnicity. Studies on the association between pregnancy intention and preterm birth may need to be group-specific.