Unintended pregnancy and preterm birth.

About one-third of all pregnancies that result in live births in the US are unintended. Despite the large number of these births, little is known about the outcomes of unintended pregnancies. The purpose of the current study was to evaluate the association between intendedness of pregnancy and preterm birth in a large prospective cohort of women who reported for prenatal care. Pregnant, black, low-income women were enrolled into this study at four hospital-based prenatal care clinics and one off-site hospital-affiliated prenatal clinic in Baltimore City. A self-administered questionnaire to assess demographic and psychosocial data was completed by each woman in the cohort at the time of enrolment in the study. The questionnaire contained an item to measure intendedness of the pregnancy. A total of 922 women comprised the final sample for analysis. For the analyses, intendedness was dichotomised as: intended (wanted now or sooner) vs. unintended (mistimed, unwanted or unsure). Overall, 13.7% of all births to women in the sample were preterm. In a logistic regression model, after controlling for potential confounding by clinical and behavioural predictors of preterm delivery, unintended pregnancy was significantly associated with preterm delivery (adjusted RR = 1.82, 95% confidence interval [1.08,3.08], P = 0.026). In this study of a cohort of urban, clinic-attending, low-income, pregnant black women, unintended pregnancy had a statistically significant association with preterm birth. After adjustment for behavioural and clinical risks, women with unintended pregnancies had almost twice the risk of a preterm delivery as women with intended pregnancies.