40 weeks or 9 months

Question

I'm a bit confused about how 9 months is also 40 weeks, should that not be 10 months? 

Can anyone explain? I've looked it up in my pregnancy book but cant find an explanation.

shanell2468 · Answer

When counting pregnancy, you have to be aware that many pregnancy's go to last up to 40 weeks and some last about one or two weeks longer or less. The method of counting can be confusing, but being that every month has different numbers of day, you have to literally count by the week and not the day. The 40th week is basically the 9th month, but when you make it to week 40, you are actually in the 1st day of the 10th month. So, to sum everything up, pregnancy goes up to the 10th month, but it is enduced if it goes beyond that.

kerriekab · Answer

40 weeks is how long they say pregnancy lasts.  This equates to 9 calendar months because some months have 5 weeks in them.  Its actually 10 lunar months which are 4 weeks each. 

So when you are 20 weeks it would seem that you are 5 months but really you are 4 and a half months. Its confusing but just the way it works. Most proessionals go by weeks.

LosingMyMindInGA · Answer

I think you've got it now :)  This is why most docs go with weeks and don't even bother with months.  It's just so confusing.  I've had 6 full term pregnancies and it took me til number 5 to fully understand it LOL

claire5522 · Answer

Yeah I think I've got my head around it now.  The way it makes most sense to me is that there is 4.45 weeks in a calender month. So the way to think about trimesters is:

Month 1= 4 Weeks
Month 2= 4 weeks
Month 3= 5 weeks
End of first Trimester

Month 4= 4 weeks
Month 5= 4 weeks
Month 6= 5 weeks
End of second trimester

Month 7= 4 weeks
Month 8= 5 weeks
Month 9= 5 weeks
Baby arrives

I was rounding months to weeks which I shouldn't have been doing!!!

Thank you everyone for your posts :)

LosingMyMindInGA · Answer

Your due date is technically the end of the ninth month beginning of the tenth.  

weeks:
1-4 are month one
5-8 are month two
9--12 are month three
13-16 are month four
17-20 are month five
21-24 are month six
25-28 are month seven
29-32 are month eight
33-36 are month nine
37 weeks starts the tenth month technically

If you are 29 weeks pregnant you would be SEVEN months and  ONE WEEK pregnant. So technically you are actually IN your eight month...but have not completed the full 8 months.

Does that make more sense?

mamaof4410 · Answer

I go by 40 weeks..10 months. Like right now i'm 26 weeks at 28 weeks i will be 7 months pregnant. I dont do the month to month thing. And my doc goes by the weeks. So every 4 weeks i turn another month.

chantal21 · Answer

http://www.babiesonline.com/articles/pregnancy/a10monthpregnancy.asp

This may either help or confuse you more. lol

alaysha · Answer

Your due date is the first day of month ten. Before that you are still 9 months.

Lemenna · Answer

9 Calendar months...so when you just go from say the 12th to the 12th of each month...but really 10 months when looking at a month being a set of 4 weeks. Obviously each month is not 4 weeks so you get the extra days to account for. So when you look at the total year it is 12 calendar months but 13 sets of 4 weeks. Hopefully I didn't just confuse you more!