ABSTRACT: BACKGROUND AND OBJECTIVES:The number of women of childbearing age with chronic diseases is rising. Evidence has shown that obstetric complications and poor psychological well-being are more prevalent among this group, in addition to these women reporting experiences of less than satisfactory care. More research is needed to investigate how to best meet the special needs of this group during pregnancy and postpartum. Previous research has shown that care coordination, continuity of care, woman-centered care, and specialized maternity care interventions delivered to women with high-risk pregnancies can improve patient-reported outcomes and pregnancy outcomes and be cost-effective. However, no previous trials have examined the efficacy and cost-effectiveness of such interventions among pregnant women with chronic diseases. This paper describes the protocol of a randomized controlled trial (RCT) of a midwife-coordinated, individualized and specialized maternity care intervention (ChroPreg) as an add-on to standard care for pregnant women with chronic diseases. METHODS/DESIGN:This two-arm parallel group RCT will be conducted from October 2018 through June 2020 at the Department of Obstetrics, Copenhagen University Hospital, Rigshospitalet, Denmark. Pregnant women with chronic diseases are invited to participate; women will be randomized and allocated 1:1 to the ChroPreg intervention plus standard care or standard care alone. The ChroPreg intervention consists of three main components: (1) coordinated and individualized care, (2) additional ante- and postpartum consultations, and (3) specialized midwives. The primary outcome is length of hospital stay during pregnancy and in the postpartum period, and secondary outcomes are psychological well-being (five-item World Health Organization Well-Being Index, Edinburgh Postnatal Depression Scale, Cambridge Worry Scale), health-related quality of life (12-Item Short Form Health Survey), patient satisfaction (Pregnancy and Childbirth Questionnaire), number of antenatal contacts, and pregnancy and delivery outcomes. Data are collected via patient-administered questionnaires and medical records. DISCUSSION:This trial is anticipated to contribute to the field of knowledge on which planning of improved antenatal, intra-, and postpartum care for women with chronic disease is founded. TRIAL REGISTRATION:ClinicalTrials.gov, NCT03511508 . Registered April 27, 2018.