The Due Date is Wrong

Unfortunately there are many problems today because the due date is not calculated correctly. To begin with I’d like to ask you a question: “Doesn’t it seem odd that we are taught to ask the doctor to tell us when the baby was made?”

We are told to track our cycle and write down when we are having our periods. It’s very important that we do this. But isn’t it at least as important to take notes when we have sex—especially if we want to get pregnant. Why does nobody tell us this?

How can the doctor know when we had sex?

One other way for doctors to cross-check the due date is to use ultrasound. But I again want to invite you to ask yourself a question: if we look at either a child or an adult, do we know how old they are just by knowing their (estimated!) height and weight?


When doctors calculate the due date they always assume that ovulation took place on day 14. But this is not the case in most cycles. So if we do not ovulate on day 14 and haven’t even had sex on or around day 14, the baby cannot have been made on that day. And therefore, the due date is not calculated correctly. Especially in the techno-medical model of maternity care a miscalculated due date can have a tremendous impact on pregnancy, birth, postpartum, parenting—and life.


When we ask women about their birth experience, the following scenario is common:

As the incorrectly calculated due date draws near, the woman is longing for pregnancy to be over. Her day to day life is more and more difficult because her belly has gotten really big by now. And she can’t wait to have the baby in her arms. When the calculated due date arrives the woman is told to go to the hospital to be checked. If nothing happens she has to go back every other day to be checked again. Care providers at the hospital are getting nervous. They start telling her that if still nothing happens they will induce birth with pharmaceutical drugs and if that doesn’t help either they will perform a cesarean.

Hearing all this the woman is getting nervous as well. She loses trust in her body and doubts that she is capable of giving birth. The woman is not supported by the people surrounding her. Instead of encouragement, women are made to believe that we need the help of drugs and technology to be able to give birth. And if you start with one intervention often more interventions are needed. That’s why the cesarean rate in almost all western, developed countries that are primarily using the techno-medical model of maternity care is more than 30 % [1 in 3].


The very sad part is that a lot of times an incorrect due date leads to man-made induced prematurity. If ovulation has not taken place on day 14 but let’s say on day 35 (which sure can happen) and birth is induced on EDD + 10 it would actually be only week 39! This means that we are not trusting the baby to tell us when it’s ready to come to this world but instead we do something that can have a huge impact and severe consequences for both the mother and the baby.

And one more thing to think about is that the duration of pregnancy can vary just like other happenings in life. Do we all get our first period at the same age? Do all teenage boys get the change of voice at the same age? Do we all enter menopause at the same age? Or do all apples on a tree mature at the same time? Pregnancy doesn’t always have to be exactly 40 weeks. It can be less and it can be even 42 weeks.


If we want to calculate the due date, here is a method to correctly calculate it. For this method it is very helpful if you not only track your periods but also your cycle observing the cervical mucus and/or temperature. If you have any questions about this, go to my website or contact me [see links below].

Pregnancy normally has a length between 260 and 268 days (+/- 8 days)

To calculate the due date correctly you need to take

  • the day with the peak of cervical mucus or
  • the 2nd day before raise of temperature or
  • the date of conception (based on records)

minus 7 days, plus 9 months


Day with peak of cervical mucus: February 15th

February 15th – 7 days + 9 months = November 8th


Birth can and ought to be such a wonderful even pleasurable and empowering experience preparing us for motherhood. But that’s almost impossible as long as we trust technology and the intellect more than nature and our intuition. That’s why it’s so important that us women get to know our body again, pass on the knowledge to other women and our daughters, take responsibility and trust in ourselves.

Angelika Leibnitz is a biologist, expert on the female cycle, doula and childbirth educator. She believes that all our female topics such as menstruation, fertility, femininity, sexuality, pregnancy, birth, postpartum and menopause are not a failure of nature. There is so much wisdom and strength in being feminine and it’s her mission to spread this message of female awareness. Contact her or visit her website about the female cycle.

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Peggy O'Mara

About Peggy O'Mara

Editor and Publisher of Longtime natural living advocate, award winning writer, and independent thinker.

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