Among those who delayed childbearing into their 30s or 40s and then sought
fertility treatment, 40% of women “strongly agreed” they regretted the delay,
according to Adachi, Endo, and Ohashi’s cross-sectional study of 449 patients
across nine Japanese fertility clinics (BMC Public Health, 2020). A companion
study by the same group found that 57.5% agreed — to any degree — that they
wished they had decided earlier. The gap between those figures (40% vs 58%)
reflects the difference between strong and any agreement; the entry uses the
stricter 40% to avoid overstating the rate. Notably, the primary driver of
delay regret in both studies was not age per se but lack of fertility knowledge:
people did not understand that fertility declines significantly in the mid-30s,
and they regretted not knowing sooner.
On the early-parenthood side, a 2025 online survey of 2,000 US parents by the
Headway app found that 24% wished they had waited longer before starting a
family, and 46% reported not achieving personal goals before parenthood
reshaped their priorities. This is not a peer-reviewed study, but it aligns
directionally with a large Danish register study (Journal of Marriage and Family,
Johansen, Nielsen & Verner, 2020), which found that early parenthood — defined
as before age 21 — significantly reduced educational attainment and employment
for both mothers and fathers, with the catch-up period extending into the early
30s even in a Nordic welfare state with generous support.
The comparison between these two sides should be treated as directional, not
precise. The inaction regret rate is drawn from a fertility-clinic sample —
people who delayed and then experienced fertility difficulty — which imposes a
double-selection that likely inflates the figure substantially relative to all
delayed parents. Gilovich and Medvec’s framework predicts that inaction regrets
intensify over time (the closed fertility window cannot be reopened), while
action regrets (lost career opportunities, constrained finances in young
adulthood) tend to attenuate as circumstances improve. The 16-percentage-point
gap between 24% and 40% is consistent with that pattern, though the different
populations and methodologies mean it should not be read as a precise estimate
of the asymmetry.
Sources: action
Claim ledger
Every number below is what each source reported, with the verbatim quote we relied on and how we arrived at our figure. Click any link to verify directly.
[1]Headway App / OnePoll — Parenting and Personal Development Survey: Career vs Kids
Reference source
24% of parents wish they had waited to have children; 46% regret not achieving goals before parenthood
Excerpt
“"24% wish they had waited to have children... 46% of parents regret not achieving their goals before having children."
”
Source data from
2025-09-25
Accessed
2026-05-02
Calculation
OnePoll online survey of 2,000 US adults with children, September 2025. The 24% "wish they had waited" figure is used directly as the action-side regret rate. This captures timing regret (started too early) rather than parenthood regret per se. The survey is not peer-reviewed; it serves as a population-level proxy in the absence of a large-scale academic survey measuring early-parenthood timing regret directly.
[2]Journal of Marriage and Family / Johansen, Nielsen & Verner — Long-Term Consequences of Early Parenthood
Peer-reviewed
Early parenthood (before age 21) significantly reduced educational attainment and employment for both mothers and fathers; effects persisted through the late 20s and early 30s
Excerpt
“"Early parenthood had a negative impact on educational attainment and employment. The estimated effects for men were substantial and only slightly less than for women; catching up to the nonyoung parents continued throughout the late 20s and early 30s."
”
Source data from
2019-11-25
Accessed
2026-05-02
Calculation
Danish register-based study using sibling fixed effects, cohorts born 1968–1977, examining outcomes at ages 22–35. The study does not measure regret directly but documents the opportunity costs (reduced education, earnings) that drive action-side regret. Used as corroboration that the early-parenthood penalty is real and persistent even in a generous Nordic welfare state, lending plausibility to the 24% timing-regret figure.
Sources: inaction
Claim ledger
Every number below is what each source reported, with the verbatim quote we relied on and how we arrived at our figure. Click any link to verify directly.
[1]BMC Public Health / Adachi, Endo & Ohashi — Regret over the delay in childbearing decision negatively associates with life satisfaction among Japanese women and men seeking fertility treatment: a cross-sectional study
Peer-reviewed
40.3% of women (102 of 253) answered 'strongly agree' regarding regret over the delay in their childbearing decision; 21.9% of men reported the same
Excerpt
“"Of the 253 women and 196 men, 102 (40.3%) women and 43 (21.9%) men answered 'strongly agree' regarding their regret over the delay in the childbearing decision."
”
Source data from
2020-06-05
Accessed
2026-05-02
Calculation
Cross-sectional survey of 449 adults attending nine fertility facilities in Japan, July–December 2018. The 40.3% "strongly agree" figure is the strictest available operationalization of delay regret and is used as the inaction-side rate. This population is subject to selection bias: those who delayed AND subsequently experienced fertility difficulties are over-represented relative to all who delayed. The true population-level rate for those who delay parenthood is therefore likely lower than 40.3%; this figure should be read as a ceiling, not a prevalence estimate.
[2]Nursing Open / Adachi, Endo & Ohashi — Uninformed decision-making and regret about delaying childbearing decisions: A cross-sectional study
Peer-reviewed
57.5% of women in fertility treatment agreed they wished they had made childbearing decisions earlier; lack of fertility knowledge was the primary predictor of regret
Excerpt
“"57.5% of women agreed they wished they'd decided earlier about having children... lack of fertility knowledge was a significant positive predictor of regret over the timing of the childbearing decision in both women and men."
”
Source data from
2020-08-17
Accessed
2026-05-02
Calculation
Same research group and overlapping sample (388 adults from the same nine Japanese fertility clinics, July–December 2018). The broader 57.5% "agreed" figure (including weak agreement) corroborates the BMC 40.3% "strongly agree" figure. Both use fertility-clinic samples. The entry uses the stricter 40.3% to avoid inflating the inaction rate. The key additional finding — that lack of fertility knowledge predicts regret more than any other factor — suggests much of the delay-regret is informational rather than preference-driven.
Caveats
The two sides draw on non-equivalent populations and methodologies, limiting direct comparison. The inaction-side figures (40–58%) come from fertility clinic patients — a sample defined by the intersection of having delayed AND experiencing subsequent fertility problems. This double-selection sharply inflates the apparent regret rate versus the full population of those who delay. The true inaction-regret rate for all delayed parents (most of whom conceive without difficulty) is almost certainly lower. The action-side figure (24%) comes from an online panel survey of all parents, which lacks the clinical selection bias but is also not peer-reviewed. Gender asymmetry is pronounced in the inaction data: women report delay regret at roughly twice the rate of men (40% vs 22% "strongly agree"), likely reflecting the greater biological cost of delayed conception for women. The existing entry advanced-maternal-age-birth-defect covers health risks of delayed conception; this entry captures timing regret only. Cross-cultural differences are significant: the inaction studies are Japanese; Japan has above-average social pressure around timely marriage and childbearing, which may inflate regret relative to US or Northern European populations.
