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Naegele's Rule is a standard way of calculating the due date for a pregnancy. It is named after Franz Karl Naegele (1778-1851), the German obstetrician who devised the rule. A due date is the date at which a pregnant woman is due to give birth. ...
This article is about human pregnancy in biological females. ...
An eponym is the name of a person, whether real or fictitious, who has (or is thought to have) given rise to the name of a particular place, tribe, discovery, or other item. ...
Year 1778 (MDCCLXXVIII) was a common year starting on Thursday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Monday of the 11-day slower Julian calendar). ...
1851 (MDCCCLI) was a common year starting on Wednesday (see link for calendar) of the Gregorian calendar (or a common year starting on Friday of the 12-day-slower Julian calendar). ...
History
Franz Karl Naegele was born July 12, 1778, in Duesseldorf, Germany. In 1806 Naegele became ordinary professor and director of the lying-in hospital in Heidelberg. His "Lehrbuch der Geburtshuelfe," published in 1830 for midwives, enjoyed a successful 14 editions.
The rule estimates the Expected Date of Delivery (EDD) from the first day of the woman's Last Menstrual Period (LMP) by adding a year, subtracting three months and adding seven days to that date. This approximates to the average normal human pregnancy which lasts 40 weeks (280 days) from the LMP, or 38 weeks (266 days) from the date of fertilisation. Example, if LMP was 8 May 2007, then +1 year = 8 May 2008, -3 months = 8 February 2008, +7 days = 15 February 2008; whereas precisely 280 days would be 12 february 2008. The menstrual cycle is the periodic change in a womans body that occurs every month between puberty and menopause and that relates to reproduction. ...
Assumptions This method is a fairly good estimation of the due date, but makes a number of assumptions. - An average menstrual cycle
- The rule is based on ovulation and fertilization happening on cycle day 14 with a cycle length of 28 days. It is less accurate when ovulation happens earlier or later in the cycle, and for women with irregular menstrual periods. Sometimes women may have a light bleed of a threatened miscarriage in early pregnancy, which adds to this confusion if it is mistaken for a period.
- Average lengths of calendar months
- The rule assumes an average length for all months in the Gregorian calendar year of just over 30 days (365 / 12 = 30.416). The rule, on average, therefore equates to 280.75 days. However the unequal length of the Gregorian calendar's months results in Naegels's rule overestimating the EDD by 3 days for all LMPs in May, and depending on the effect of leap years gives precise dates on only either 2, 5 or 7 months of the year.
- Average gestation
- The rule assumes 40 weeks, or 280 days from LMP. Recent studies have suggested that the EDD would be better estimated using 282 days from the LMP date (40 weeks and 2 days),[1] this is not though current accepted clinical practice.
Miscarriage or spontaneous abortion is the natural or spontaneous end of a pregnancy at a stage where the embryo or the fetus is incapable of surviving, generally defined in humans at a gestation of prior to 20 weeks. ...
For the calendar of religious holidays and periods, see liturgical year. ...
For the 1921 film starring Fatty Arbuckle, see Leap Year (film). ...
Other estimation techniques The effects of varying lengths of the calendar months may be overcome by use of hand operated pregnancy wheel devices, or the use of electronic computer pregnancy calculator programs.
Ultrasound confirmation of gestational age Since the estimation is based on the LMP date, Naegele's rule can easily be a week or more off, it should be used to calculate a range of due dates and confirmed with ultrasound in the first trimester. Since the 1970's ultrasound scans have allowed measurement of the size of developing embryos directly and so allow for an estimation of gestation age. Ultrasound dating is most accurate if undertaken in the first trimester (first 12 weeks of pregnancy) with a 95% error margin of 6 days. Scans performed in the second trimester have an error margin of 8 days and those in the third trimester a margin of 2 weeks.
Most obstetric departments in Australia, United Kingdom and United States use a combination of LMP and ultrasound based estimates for the EDD using either 10-day or 7-day rules, so that if LMP dates and ultrasonographic dates are in agreement within 7 (or 10) days, then the LMP dates are accepted.
References eMedicine is an online clinical medical knowledge base that was founded in 1996. ...
Footnotes - ^ Nguyen T, Larsen T, Engholm G, Møller H (1999). "Evaluation of ultrasound-estimated date of delivery in 17,450 spontaneous singleton births: do we need to modify Naegele's rule?". Ultrasound Obstet Gynecol 14 (1): 23-8. PMID 10461334.
External link - Pregnancy Calendar and Calculator - due date calculator
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