This systematic review and meta-analysis aimed to determine mean estimates of prevalence rates for fulfilling all diagnostic criteria of posttraumatic stress disorder (PTSD) or at least showing significant levels of posttraumatic stress (PTSS) in relation to the traumatic event of childbirth. For the first time, both mothers and fathers were included in the synthesis. Studies were identified through systematic database search and manual searches, irrespective of language. Meta-analyses of 154 studies (N = 54,711) applied a random-effects model to four data sets, resulting in pooled prevalence rates of 4.7% for PTSD and 12.3% for PTSS in mothers. Lower rates of 1.2% for PTSD and 1.3% for PTSS were found among fathers. Subgroup analyses showed elevated rates in targeted samples (those with a potential risk status) most distinctly for maternal PTSS. The significant amount of heterogeneity between studies could not be explained to a satisfactory degree through meta-regression. Given the substantial percentage of affected parents, the adoption of adequate prevention and intervention strategies is needed. As this field of research is evolving, attention should be broadened to the whole family system, which may directly and indirectly be affected by birth-related PTSD. Further studies on paternal PTSD/PTSS are particularly warranted.