The 7.0% overall 5-year cumulative probability of regret after tubal ligation comes from the US Collaborative Review of Sterilization (CREST), as summarised in the AAFP 2002 clinical review of 3,672 women who underwent tubal ligation between 1985 and 1987. The longer-horizon CREST report by Hillis et al. (1999, Obstet Gynecol, PMID 10362150) followed a larger cohort of 11,232 women aged 18-44 sterilised between 1978 and 1987 for up to 14 years; it publishes only age-stratified figures, and those reveal large heterogeneity: women sterilised at age ≤30 had a 14-year regret probability of 20.3%, compared to 5.9% for women sterilised after age 30. Neither the Hillis abstract nor the AAFP reviews report a single pooled 14-year figure, so the 7.0% 5-year overall rate is used here and is conservative relative to the 14-year horizon. The AAFP clinical guidance (2003) cites young age at sterilisation as one of the two most common factors associated with regret (alongside unpredictable life events such as a change in marital status). On the inaction side, no published survey directly measures regret among women who chose not to have tubal ligation; the 5% inaction proxy is constructed from unintended-pregnancy burden data and is a placeholder estimate, not a finding.
Tubal ligation is one of the most clearly documented exceptions to the Gilovich and Medvec pattern that inaction regret dominates over time. The mechanism is well understood: the procedure is surgically permanent, irreversible without costly and uncertain reversal surgery, and often performed at ages when life circumstances — partner status, child survival, financial stability — can change substantially. The three most common precipitants of regret identified in CREST follow-up data were a change in marital status (divorce, remarriage), the death of a child, and a desire for more children with a new partner. These are not predictable at the time of surgery and are not failures of informed consent; they are inherent features of a permanent decision made in a probabilistic future. Women who were sterilised after age 30 with completed families and stable relationships had very low regret rates (5.9%), suggesting the procedure is nearly regret-free when the risk factors for life-circumstance change are lower.
The inaction proxy is deliberately conservative. A woman who chose not to undergo tubal ligation retains reproductive options and can revisit the decision at any time — the classic Gilovich mechanism for suppressing inaction regret. However, women who forewent sterilisation and subsequently experienced unintended pregnancies, or who bore the full contraceptive burden for years while their partners avoided vasectomy, may harbour meaningful retrospective inaction regret that no current survey captures. The delta (0.02) is small and should be read as indicating that action regret is modestly higher than inaction regret for the general population of women who consider tubal sterilisation — but the action side rests on a 5-year overall rate while the inaction figure is a soft editorial proxy, so the true direction could shift for subgroups (and the action side would be considerably larger at a 14-year horizon, especially for women sterilised before age 30).