BACKGROUND: There is no clear evidence about how to support people with borderline personality disorder (BPD) during the perinatal period. Perinatal emotional skills groups (ESGs) may be helpful, but their efficacy has not been tested.

AIMS: To test the feasibility of conducting a randomised controlled trial (RCT) of perinatal ESGs for women and birthing people with BPD.

METHOD: Two-arm parallel-group feasibility RCT. We recruited people from two centres, aged over 18 years, meeting DSM-5 diagnostic criteria for BPD, who were pregnant or within 12 months of a live birth. Eligible individuals were randomly allocated on a 1:1 ratio to ESGs + treatment as usual (TAU), or to TAU. Outcomes were assessed at 4 months post randomisation.

RESULTS: A total of 100% of the pre-specified sample (n = 48) was recruited over 6 months, and we obtained 4-month outcome data on 92% of randomised participants. In all, 54% of participants allocated to perinatal ESGs attended 75% of the full group treatment (median number of sessions: 9 (interquartile range 6-11). At 4 months, levels of BPD symptoms (adjusted coefficient -2.0, 95% CI -6.2 to 2.1) and emotional distress (-2.4, 95% CI -6.2 to 1.5) were lower among those allocated to perinatal ESGs. The directionality of effect on well-being and social functioning also favoured the intervention. The cost of delivering perinatal ESGs was estimated to be £918 per person.

CONCLUSIONS: Perinatal ESGs may represent an effective intervention for perinatal women and birthing people with BPD. Their efficacy should be tested in a fully powered RCT, and this is a feasible undertaking.

TRIAL REGISTRATION: ISRCTN80470632.