Evidence on this so far is anecdotal, only because it would be very hard to study this scientifically in a reliable way. At IAPMD we hear from many people whose symptoms started or worsened after pregnancy/having a child/children, however it is also known that PMDD tends to worsen with age and stress, which are both associated with having children.
It is difficult to know whether the biological process of pregnancy/having children would worsen any symptoms or if it is the extra stressors/lack of sleep/change in lifestyle that would cause this, or a combination of both! This is an area which requires further research.
It is important to talk your concerns through with a trusted healthcare professional and work towards having a support system in place for when your menstrual cycle returns post-pregnancy.
IAPMD run 2 support groups for Moms with PMDD: