To describe self-reported maternal-fetal emotional attachment in adolescent women over the course of pregnancy, compare it with adult pregnant women, and identify risk factors for poor attachment. Design: A prospective cohort study. Setting: Young mothers clinics in 2 public hospitals in metropolitan Melbourne, Australia. Participants: English-speaking young women aged 20 years and under attending their first antenatal visit. Methods: Self-report questionnaires were completed in each trimester. Validated measures were used to assess anxiety and depression symptoms and maternal-fetal emotional attachment. Data were analyzed with existing data from pregnant adults. Regression analyses were conducted to establish factors independently associated with higher mean first-trimester attachment score and lowest-quartile third trimester score adjusting for confounding variables. Main Outcome Measure: Maternal-fetal emotional attachment, assessed by the Quality and Intensity subscales and Global score on Maternal Antenatal Attachment Scale (MAAS). Results: 165/194 (85 ) completed the first questionnaire; 130/165 (79 ) provided complete data. Mean anxiety but not depression scores were significantly higher in adolescents than adults across pregnancy. Mean (95 CI) first-trimester adolescent Global MAAS was significantly lower than adults (70.3 (68.4, 72.2) vs 76.8 (75.4, 78.2) P .01), but there were no significant second- or third-trimester betweengroup differences. Adjusted odds of a lowest-quartile third-trimester MAAS score was significantly associated with lower first-trimester score (P .001), previous abortion (P 5 .02) and being born overseas (P 5 .002). Conclusion: Adolescents report slower development of antenatal emotional attachment than adults. Women with risk factors for poor attachment in late pregnancy are identifiable in early pregnancy and may benefit from additional multidisciplinary care.