A woman reports that her last normal menstrual period began on August 5, 2024. What is this woman's expected delivery date using Nägele's rule?

Choice A rationale Nägele's rule involves adding 7 days to the first day of the last normal menstrual period (LNMP) and then subtracting 3 months. The LNMP is August 5, 2024. Adding 7 days gives August 12. Subtracting 3 months from August results in May. Therefore, the estimated date of delivery (EDD) is May 12, 2025. This choice is incorrect based on this calculation. Choice B rationale Nägele's rule is the standard method for estimating the expected date of delivery (EDD). It is based on the assumption that conception occurred on day 14 of a regular 28-day cycle. The calculation involves adding 7 days to the first day of the last normal menstrual period (LNMP) (August 5 + 7 days = August 12) and then subtracting 3 calendar months (August - 3 months = May). Thus, the EDD is May 12, 2025. Choice C rationale This date is incorrect. This date would be calculated by adding 7 days (August 12) and then potentially using an incorrect month or number of days. Nägele's rule relies on the 7-day addition and 3-month subtraction to estimate the 40 weeks (280 days) of gestation from the LNMP, which consistently yields a date of May 12, 2025, for an August 5, 2024, LNMP. Choice D rationale This date is incorrect. A date of May 5, 2025, would suggest that 3 months were subtracted, but no days were added, or an incorrect number of days was added to the LNMP. Accurate application of Nägele's rule is essential for prenatal care planning and involves adding exactly 7 days to the first day of the last menstrual period, resulting in the correct EDD of May 12, 2025.