INTERSECT Study: Birth-Related PTSD (Ayers & Handelzalts, Psychological Medicine, 2025)
4-6% clinical PTSD. 17% sub-clinical. Consistent across 31 countries.
11,302 women across 31 countries. Confirms a consistent 4-6% clinical PTSD rate from birth, with 17% sub-clinical symptoms. This is not cultural. It is systemic.
INTERSECT was a 2025 cross-national study published in Psychological Medicine, one of the leading psychiatric journals. The team led by Ayers and Handelzalts pooled data from 11,302 women across 31 countries to test how consistent birth-related PTSD prevalence is across cultures, health systems, and birthing settings. The result held remarkably steady.
About 4 to 6 percent of women in every country sampled met full clinical PTSD criteria following childbirth.
Another 17 percent showed sub-clinical symptoms severe enough to impair daily functioning but not quite meeting the diagnostic threshold. The fact that the rate is consistent across 31 countries rules out the easy explanation that birth trauma is a culture-bound phenomenon or an artifact of particular hospital systems. It suggests instead that something about modern obstetric care itself is producing this rate.
11,302
Women in the study
31
Countries sampled
4-6%
Clinical PTSD rate
17%
Sub-clinical symptoms
Why it matters
When the same number shows up in 31 different countries, the cause is not cultural. It is built into how birth is being delivered, and that means it can be changed.
This is one finding from the research library behind How to Birth a Mother. Everything here traces back to a study, a dataset, or a systematic review.