Autistic people may be at higher risk of perinatal mental health conditions, given that autism and mental health conditions commonly co-occur and that autistic people face additional stressors such as barriers to appropriate maternity care. This study explored self-reported stress, depression, anxiety and satisfaction with life during the third trimester of pregnancy (n = 27 autistic women; n = 25 non-autistic women), 2 to 3 months after birth (n = 24 autistic women; n = 26 non-autistic women) and 6 months after birth (n = 22 autistic women; n = 29 non-autistic women). Self-reported parenting confidence and parenting styles were explored at 6 months after birth. Autistic participants scored significantly higher than non-autistic participants on stress, depression and anxiety across the time-points as a whole, although there were no group differences for satisfaction with life. Anxiety scores significantly decreased over time for both groups. No group differences were found for parenting confidence nor parenting anxiety, nurturance, involvement or routine, although the autistic group scored lower on parenting discipline. The findings highlight the need for effective screening and support for perinatal mental health conditions for autistic people. Professionals working with autistic parents should be aware that autistic and non-autistic parents report being equally likely to engage in positive parenting behaviours such as nurturance and involvement.