24/04/2021
Due dates are bo****ks.
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Only 4% of babies are born on their due date...4!!
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So where does the theory behind due dates come from?
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A recent post by describes it perfectly
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Posted • Research published in the April 2021 Australian and New Zealand Journal of Obstetrics and Gynaecology has again highlighted that the idea of a fixed due date “stretches credulity.”
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Gerald Wightman Lawson searched and analysed the medical literature relating to "variables on the length of pregnancy, the expected date of confinement, and prolonged pregnancy."
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His research showed that, "a number of factors were found to significantly influence the length of a pregnancy, including ethnicity, height, variations in the menstrual cycle, the timing of ovulation, parity and maternal weight." (Lawson 2020)
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And for those who would like a bit more detail...
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"The proposition that a pregnancy is 40 weeks or 280 days in duration is attributed to the German obstetrician Franz Naegele (1778–1851). His rule adds nine months and seven days to the first day of the last menstrual period. The expected date of confinement from this formula is approximately right in the majority of cases. However, the idea that this rule can apply to every pregnant female – young or old, nulliparous or multigravida, Caucasian, Asian, African, or Indigenous – stretches credulity. In addition, many women regard the 40‐week date as a deadline, which if crossed, may then place the baby under stress. Forty weeks is such a simple, round, convenient figure that it has proved difficult to challenge, despite criticism. Nonetheless, what might have been an appropriate formula in Germany in the 19th century deserves to be revisited in the 21st."
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You can see the paper at https://obgyn.onlinelibrary.wiley.com/doi/10.1111/ajo.13253
