(My real “Week Forty” pregnancy post is coming later. This is just an informational post about due dates for those who are interested.)
As many of you know, I went past 40 weeks with Vera. Thirteen days past, actually. Many of us rely on that “magical due date” to predict when our little sweetie will arrive, but the system for calculating it is actually rather flawed. First of all, this method (which dates back to the 1700’s) assumes that each woman’s cycle is the same length (28 days). A woman with shorter cycles is going to have a shorter gestation, and likewise, a woman with longer cycles will have a longer gestation. Secondly, this method incorrectly represents a lunar month as 280 days rather than the actual 295 days (yep… a 15 day difference!).(1)
A more accurate method for determining one’s due date (Mittendorf, et. al. 1990 study) is to take the date of your last cycle, subtract 3 months, and add 15 days (for first time moms) or 10 days (for moms who have previously given birth).(2) According to this way of calculating, I am not actually even “due” until February 18 or 19.
Another source suggested taking the doctor’s calculated due date for you (280 days) and adding or subtracting days based on the average length of your cycle. Add or subtract 2 days for every day difference there is between your cycle length and the standard 28 days. If you typically have a cycle that lasts 30 days, add 4 days to the end of your “due date” (from the doctor), and if you normally have a shorter cycle (like 27 days), subtract 2 days.(3) According to this way of figuring the due date, I am due February 19 or 20.
I also found some really interesting information about inductions. You may have heard that it is important to be induced at 41 weeks (I was told last time by my doctor that after 41 weeks the risk of stillbirth doubles), yet did you know that the American College of Obstetricians and Gynecologists (ACOG) does not recommend labor induction until 42 weeks? In a study done of over 56,000 pregnancies, the ACOG concluded: “Routine labor induction at 41 weeks likely increases labor complications and operative delivery without significantly improving neonatal outcomes.”(4) Interesting! I’ll definitely be pushing for a late induction date (right at 42 weeks, if possible) if I am still pregnant at that point.
I hope that this post has been informative for you. I feel like I’m learning a lot right now… not just about pregnancy/delivery, but about patience and trusting in God for HIS perfect timing!
When our family went through a difficult time when I was in middle school, we clung to this verse: “Some trust in chariots and some in horses, but we trust in the name of the LORD our God” (Psalm 20:7). We filled in “chariots” and “horses” with what we were tempted to trust in at the time, and determined to trust in GOD, not in those things! Some may trust in doctors and due dates, but we trust in the name of the LORD our God! 🙂
Sources:
(1) The Lie of the EDD
(2) Ibid.
(3) gentlebirth.org
(4) Forty Weeks and Beyond
Interesting!
I hope you don’t have to be induced! I remember those last weeks and days being the hardest. I was blessed to go into labor at 11 p.m. on my due date so I didn’t have to go through too much impatience, but I still remember it being hard! Praying you are able to enjoy these last few days of your pregnancy!
This was really interesting to read! The explanation that I know is that not every woman ovulates on the same cycle day of the month. So you need to know exactly what day you ovulated to know when you actually got pregnant. And if you calculate from there, the date is accurate. Of course, babies still grow and develop at their own rate, give or take those few weeks 🙂
How interesting about the better method for calculating due dates! In nursing school we were taught the “old” way, and I only graduated a few years ago, so I doubt that medical professionals are being told anything other than the 280 days on a regular basis…but the fact of the matter is that for all our technology, sometimes we can be pretty dense about “new” ideas!
On another note, I am so touched by the tone of all your posts even so late in your pregnancy. As someone who would LOVE to be pregnant and can’t right now (but we are trusting the Lord for His perfect plan!), it really makes me sad to hear women complain constantly about their pregnancies. I know it’s a long time, can be very uncomfortable, alters every aspect of your life, etc…but I would love to be in their shoes and be given the gift of carrying my own child. It encourages me to hear your positive, thankful tone in spite of the sleep deprivation, desire to meet Mango NOW, and everything else, and I hope that if I am ever blessed with a biological child that I will follow your example!
Thank you for your sweet blog, I read you every single day! 🙂