Is there science behind a woman’s due date?   Why do we all pay so much attention to it?  Why is it that the minute a woman nears her due date so often those around her, including her care provider often get the look of worry and begin to fiddle; to suggest membrane stripping, extra ultrasounds, and even induction.  I hope that I can answer these questions and help women feel more secure in the last few weeks of their pregnancy.

I personally never thought much of a due date, which is why I prefer calling them guess dates.  The first thing a care provider does when meeting a pregnant women is put a magical date on the pregnancy.  Some women do not mind this at all and others feel like they are already being put in a box.  I encourage women and their care providers to have a guess date and then tell all those around them that the baby will be coming at the beginning, middle or end of a certain month, so that the phone calls will not drive the pregnant mother crazy at the end of her pregnancy.

The Estimated Date of Delivery or EDD is nothing more than a formula derived from statistical averages that say your baby will likely be born within 2-3 weeks of this time.  However the estimated date along with our plan ahead culture has caused us to be so focused on this date, that we are kicking babies out before they become fully ready.  A normal gestation is 37-42 weeks based on the mother, her history, her cycle lengths and generally how long it takes her and her baby to grow. 37-42 weeks is what is established by The World Health and American College of Gynecologists and Obstetrics, which means that post term is post 42 weeks, not 1 day after your guess date.  Women often get so uncomfortable at the end of pregnancy: endless night waking to go to the bathroom, sore hips from sleeping, heartburn and other discomforts.  It is no wonder that women go to their care provider at 39 or 40 weeks after a bad nights sleep and when asked if she would just like to, get the show on the road she may just say yes, not knowing the ramifications.  It would be so much nicer for the care provider to sympathize and give her advice by telling her, babies will not stay in forever they always come out, let your baby choose their birth date.

There are reasons for women to go beyond their due dates.  Some of the reasons are easy to change and others are just nature.  One reason for going post due is the position of the baby.  Babies that are in the posterior or deflexed head position tend to go post due which is why your midwives encourage optimal fetal positioning and have their hands on you each week to discover the position of the baby.  The position can be changed via exercise, chiropractic and homeopathic care.  Another reason for going over due is history; it is in some family’s genes to go over due.  This is what their family line does and so why would it change now.  Another reason is cycle length; women who have longer cycles tend to gestate longer.  Another reason may be genetic defects; most of these have other signs and symptoms that would become apparent in an ultrasound and or during the prenatal period.  A final reason is simply nature and we all know that we can’t control nature.

Beyond the discomforts and providers push to induce is there a reason for us to be worried about going overdue?  If you look into the research on post dates pregnancy you will find a confusing array of statistics.  The first reason for the confusion is that postdates is defined different depending on the research.  True postdates is anything past 42 weeks, however there is a vast amount of research using anything past the due date at post term.    The main concern is about the life cycle of the placenta.  Care providers worry that the placenta will stop functioning and that the baby will stop growing.  Another concern is that the baby will get to big and just wont fit any longer.  In some studies there has been a higher incidence of unknown fetal demise after 41 weeks.  The vast amount of the research actually states that the perinatal mortality increases after 42 weeks and doubles at 43 weeks.  The final concern is that the baby will have to go poo and that there will then be meconium in the amniotic fluid causing a potential for respiratory distress.  For each and every one of these concerns there is research stating the opposite.  For the past 15 plus years it is become hard to carry out post date research due to the fact that the majority of pregnancies are induced at or around their due date.

It is my trust in the birth process along with the clinical data that is gathered during the prenatal that allows me to feel completely comfortable with going “over due”.  In my experience it is rare (1-3% of mom’s per year in our practice) to go before or at their “due date”.  I trust that your placenta will sustain the baby, and that you wont grow a baby that is too big for you.  Your midwives should ask about fetal movement and should monitor that the baby is growing.  Most importantly a kettle takes forever to boil when it is being watched.  The last days/weeks of the pregnancy should be spent peacefully gestating and trusting the process.  Your care provider will be monitoring you weekly at the end to make sure your body and the baby are doing well.  There are times for induction in the rare case but a normal pregnancy tends to stay normal.