https://expectcalc.com/ Evidence-based explainers on pregnancy dating from ExpectCalc. en support@expectcalc.com https://expectcalc.com/blog/due-date-methods-gap/https://expectcalc.com/blog/due-date-methods-gap/Same last period, three dating formulas, six cycle lengths: our engine puts due dates 8 to 12 days apart, and a two-week LMP error shifts them 14 days.Fri, 23 Oct 2026 00:00:00 GMT https://expectcalc.com/blog/ivf-due-date-transfer-day/https://expectcalc.com/blog/ivf-due-date-transfer-day/One formula — transfer date plus 266 days minus embryo age — covers fresh, frozen, and retrieval dating, with worked day-3/5/6 and retrieval-only examples.Fri, 23 Oct 2026 00:00:00 GMT