maternal obesity [body mass index (BMI)≥30kg/m(2)] is a cause for concern because of increasing rates and risk of associated complications. However, little is known about how to improve the health of women with a BMI≥30kg/m(2). a 10-week antenatal lifestyle programme (The Lifestyle Course - TLC), underpinned by behaviour change theory, was developed in a programme of research which included a prospective, multicentred, feasibility phase (n=227). Participants had a BMI≥30kg/m(2) at the start of their pregnancy, planned to deliver in two areas of Greater Manchester and were aged 18 or over. The objectives were to (1) assess the feasibility of the intervention and (2) to pilot the trial processes and outcome measures. (1) Trial intervention: only 22% of women in the feasibility phase had received gestational weight advice prior to the study. One or more TLC sessions were attended by 79% of women and 97% said they would recommend TLC to a friend due to the content suitability, perceived personal gains and extra care received. Changes to the TLC were suggested and implemented in the pilot phase. (2) Trial processes: recruitment rates (36%), retention rates (100%) and questionnaire completion rates up to one year (33%) were found. Daily general 'lifestyle' diaries and pedometers were not acceptable data collection tools (response rates of 32% and 16% respectively). However, specific food diaries were acceptable (response rates of 80-81%). The major challenge was the collection of maternal weight data at the follow-up points. the antenatal intervention (TLC) designed for this programme of work appears to suit the needs of women with a BMI≥30kg/m(2). The need for an antenatal intervention is clear from this study and also highlights reflections on effective communication with pregnant women with a BMI≥30kg/m(2). Lessons learnt for designing a future trial include effective ways to communicate with pregnant women with a BMI≥30kg/m(2). ISRCTN29860479.