All About Inductions: Do Due Dates Mean Your Baby is Due?

I'm sure you know, from my past posts, the answer to that question: Most likely, no.

I abhor the term 'due date'; this term means a day of collectibility. Once you reach that estimated day of collectibility, suddenly you are considered "late". Late carries the burden (no pun intended) of being defunct, dysfunctional, or errant. "Overdue" infers something that is spoiled, going bad, or rotting (i.e. milk). Did I mention that I abhor that term?

Unfortunately, the Estimated Due Date (EDD) commonly used by health professionals is not nearly as accurate, and thus the majority of inductions are not nearly as pressing, as they claim.

Pregnancy is assumed to last 10 lunar months or 40 weeks (280 days). People often use this formula to calculate the EDD: The first day of your last menstrual period, minus 3 months, plus 7 days.

An example of using this formula:
First day of my last period was December 13th.

December 13th minus 3 months = September 13th

September 13th plus 7 days = an EDD of September 20th
This is a relatively easy formula. The problem is, it is only somewhat accurate - and then only when a woman has a regular cycle of 28 days, a luteal phase of 14 days, and did not take any oral contraceptives... uh oh, I just saw 95% of hands in the room go down.

How did we come up with this majority-inaccurate formula? Dr. Franz Naegele came up with it, which puts all women on a bell-curve for convenience and estimations' sake. It is a good guide to help estimate age, but should not be considered rule.

Carol Wood Nichols, previous Assistant Professor at Yale University School of Nursing, Maternal-Newborn Nursing/ Nurse-Midwifery Program, and Director of the Yale Nurse-Midwifery Practice, developed a calculation that takes variations in cycle length as well as previous childbearing into account.

Nichols' calculator, as cited in Anne Frye's "Holistic Midwifery Vol 1" states:

For first time moms who have true 28 day cycles: LMP (last menstrual period) plus 12 months - 2 months,14 days = EDD
Example: For December 13th, the EDD is then September 30th
For women who have different cycles or who have already had other children (multiparas), add or subtract the number of days her cycle varies from 28 days... for a full list of formulas using this rule, see below:
  1. 1st-time mothers with 28-day cycles: LMP + 12 months - 2 months, 14 days = EDD
  2. Multiparas with 28-day cycles: LMP + 12 months - 2 months, 18 days = EDD
  3. For cycles longer than 28 days: EDD + (actual length of cycle - 28 days) = EDD
  4. For cycles shorter than 28 days: EDD - (28 days - actual length of cycle) = EDD
Let's use me as an example... I don't have a normal 28 day cycle, I cycle regularly around 31 days. Using the same example as previous, I was a grandmultipara by the time I was pregnant with my son.

Hint: the EDD given by my caregiver of September 20th was grossly inaccurate. My EDD was somewhat more accurate based on the 1st-time mothers with 28-day cycles formula from Nichols, resulting in an EDD of Sept 30th...

Let's go a step further though; following Nichols' rule for cycles longer than 28 days (line 3.):
Dec. 13th plus 12 months - 2 months,14 days = Sept 30th.
Sept 30th + (31-28) = Oct. 3rd.
My son was born on October 6th.

In addition to all of this fun calculating (BTW, did I fail to mention that I had to take calculus 3 times before I passed?), there was a study performed by Mittendorf, which results showed that the average length of pregnancy is longer than usually calculated, especially for European first-time mothers. And those of us in the childbirth field can attest to the fact that most of the first-time mothers we work with deliver after their EDD as calculated by Naegele's gestational wheel. First pregnancies are often longer than subsequent pregnancies.

So, all of this to say that the EDD given by your care provider is simply to give you an idea of your baby's birth date. Don't use 40 weeks as an expiration date, but simply as a guesstimate.

When asked when your baby is due, consider telling people more vague answers to keep from prying questions (are you still pregnant?) and bothersome phone calls (have you had the baby yet?). A vague answer could very well consist of "I'm due early October".

Remember that pregnancy, on average, lasts 38 to 42 weeks, this means you have a due month, not a due day.

How do you broach this subject with your doctor? It truly helps to have a chart of your MP to prove cycle length, and gives you better bargaining chips for setting EDDs in your chart. Remember, though, you don't need to consent to an induction if your knowledge of your body conflicts with their policies.

I know that it is becoming fairly common for doctors to 'always' induce between 39 and 41 weeks. But, there is no medical justification for an induction simply for 'expiring' your EDD as determined by the Naegele Wheel. As this post just explained, it is perfectly normal and natural to go over this date. Induction for 'expiration' alone is not justified. For your and your care provider's peace of mind, though, you can start a kick chart around your EDD.

To begin a kick chart, choose a time of the day (1 hour in duration) when your baby is usually very active. For consistencies sake, try to do your kick counting at this same time every day. Relax (lie or sit down) so that you can pay attention to your baby and are not distracted by TV, work, or the computer (or you may miss the smaller movements - which you have become accustomed to over the last 32 weeks or more).

You can drink a glass of cold water to perk baby up even more right at this time if you would like. During that 1 hour count baby’s movements (this includes kicks, punches, turns, rolls, hiccups, etc..). You should be able to count around 10 or more in one hour. On the chart I linked above, when you reach 10, put an X in the window that marks the duration of time you had to wait to reach that count.

If you feel less movement than normal at that time of day and cold water does not wake him up, try for another hour after eating a small snack to give baby and you a boost in blood sugar. If baby is still less active than usual, consider consulting your caregiver.

In closing, remember, it is your choice to consent to an induction or not. An induction may sometimes be necessary, but the majority of inductions are not. Millions of healthy babies have been born after their EDD and, depending on your true estimated due date, without a medical reason for it, an induction can cause more complications and necessitate more interventions if mom's body and baby are not ready.


Molly said...

Awesome post. I think this information is really important, and not very well known. Another issue for some of us is never having had a regular cycle in the first place--if your cycle varies from fourteen to forty-or-so days with no apparent rhyme or reason, estimating that persnickety little due date is not only trickier, but harder to negotiate with a care provider! (As you know, my baby was 18 days 'late' ... and we avoided an induction ... and it was awesome.)

TopHat said...

I'm definitely done with due dates. I had shorter cycles- so when I guessed my "due date" I adjusted for that, making my "due date" a few days sooner than 40 weeks. But I was a first time mom and my baby decided to go to 43 weeks anyway. :)

I don't even know if I want to bother with "Due Months" I think I'm going to go with "Due Seasons"... sometime in the summer...

Nicole D said...

Oh, I do like your thinking TopHat!

AtYourCervix said...

I really enjoyed your post on "due dates", or rather, "due months". I am absolutely sickened by the reasons I have seen doctors come up with to induce women.

Pssst doctor: being 40 1/7 weeks is NOT "postdates"!

kris said...

trying to refrain from saying something about how of course it was a MAN who came up with edds...
luv the due seasons too:)

Michelle M. said...

I just found your blog tonight and I had to comment on this post.

I am so glad that you shared this. My son was induced at 37 weeks 3 days due to my extremely high bp (pre-eclampsia, to be exact). But the doctors never considered that he wouldn't be ready to be born. They were wrong. He spent two weeks in NICU. He went from a healthy 6 pounds 13 ounces to just five pounds. He had a really rough start. Then with my daughter, the doctors wanted me to induce her at about 41 weeks. Forunately, she was very ready to be born- I had been "laboring" for almost a week with contractions every 10-15 minutes that whole week.

All this to say, that I appreciate you sharing this info!

Danielle said...

I just found your blog also - wow, how amazing!

My daughter's due date was October 1st. That day came and went, along with the next week. People kept saying, "Oh, you're still pregnant?" and felt so sorry for me. The truth was, I was fine - great pregnancy, no complications, and I could have let her cook longer - she was only 7 lbs 7 oz @ birth! But finally I was induced on the 9th, which I was okay with, truly, even though I would have loved to go into labor on my own.

So for the next one {EDS (for season - I love that!) sometime in 2010 or 2011}, I think I might do more to go on my own, wait it out longer, and might look at NCB (I CHOSE to get an epidural the first time around).

(I've rambled on for so long, is my comment even relevant anymore?)

Anyway, thanks for all this information!!! This is wonderful!

Wendyrful said...

Fantastic post!!! I love the information you put out for mom's and everyone! As a doula and CBE, and assistant MW, I get so tired of the threats, and pressure Dr's (and society) put on pregnant mothers to have their babies by a certain date. I have seen too many awful inductions, and sad birth stories based on mom's being scared into induction. (Especially around a holiday or something similar!!!). I will link to this post for sure!


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