A due date is not an expiry date

I saw a post today on Facebook that has prompted me to write this (I see similar posts all the time, but for some reason this one inspired me!).  It said something along the lines of ‘I’m 40 weeks tomorrow, my doctor wants to do a stretch and sweep.  What should I do?’.


My immediate thought was, "walk away?".   I have yet to find any evidence that says doctors or midwives should have their fingers in your vagina before labour has started (except if you’re being induced, but that is a different subject).


I forget who said it (feel free to message me if you know) but there is a great quote that says ‘I don’t want your fingers in my vagina unless you are giving me an orgasm’.  In my opinion this is what you should say to any caregiver who wants to do an examination without good medical reason (“just to see how soon you will go into labour” is not a good reason).


But I want the subject of this article to be more about due dates.  This is something that has bugged me since I did my midwifery training…



A due date is usually given so that you can know when you would expect to meet your baby – great!  I’m all for making plans and having a rough ETA.  And if something was to happen before that date then it is good to know if the baby is going to be premature and how much care they are going to need. 


But more often than not the due date is treated more like an ‘expiry date’.  And usually it is said that it is the placenta that is going to expire or stop working. 


Please can someone tell me what other organ has an expiry date?  Because I can’t think of one….Yes, your heart, or kidneys, or liver might stop working properly, but this is usually from disease.  And in line with this, yes, if there has been ‘disease’ then the placenta might not be working well.  But this will usually show up during the pregnancy.  There is no other organ in the human body that has a set life span….why should the placenta be any different? 


So how did we come to this ’40 weeks from the first date of the last period’ rule?


Or actually, lets go back even further in time. 


How did the ancients tell time before the introduction of the Gregorian calendar? 

If you said by the moon (lunar) cycles and the seasons you would be correct. 


And how many lunar cycles did they say it would take for a pregnancy to be completed? 



Now, how many days in a lunar cycle

The most common answer is 28 days….because wouldn’t that be convenient - 28 days being exactly 4 weeks, and the supposed length of a woman’s menstrual cycle….. 


But it is actually 29.4 days, which if you multiply by 10 you get 294 days.  And if you divide that by 7 you get 42….