One of the first things people say when someone says they are expecting is “When are you due?” Everyone then starts to think about what else is happening on that day - “Oh it’s granny's birthday” , thinking of how they will plan for the big day - “I’ll book the time off of work now”, and plan out how everything can be organised around that one, suddenly crucial date.
Most things in your life quickly become associated with your due date. When to start maternity leave, the last holiday before the baby gets here, and moving home are all big things people plan with their due date in mind. You will calculate exactly how far along you are, using that date, and studiously read up on how big your baby probably is, how they have developed and whether or not your soon-to-be mini me can hear you sing to them in the womb.
The trouble with being given a due date is that it is hardly ever the day on which someone's baby is born. In our modern society we have a tendency to plan things down to the last ten minutes, expect immediate replies to our social media post and emails, and if Amazon can pin down a two-hour delivery window, why can’t we be more accurate with the deliveries of babies? Here’s why.
12 The Baby’s Due In Spring
For most of human history there has been no due date for the delivery of a baby. This was not because of ignorance of the menstrual cycle or about how long it took babies to develop, though they certainly understood all of that. The reason was that in some ways, way back when, they actually had a better understanding of pregnancy and birth than we do now.
Before the concept of a due date, if you were asked when the baby was coming you would give a time period, something like ‘late spring’ or ‘around harvest time’. This was because people then understood that babies would arrive when they were ready and that this was not on a specific date, it was when they were done developing and your body was ready to go into labor.
11 They Spent HOW Long In Hospital?
A more accurate time for the arrival of your bundle of joy was introduced for the convenience of medical staff and hospitals. Once pregnancy and birth moved from being a natural process to a medical condition for every woman, a mom-to-be was expected to go to the hospital, deliver her baby and stay in the hospital for up to two weeks afterward. This was known as your confinement to the hospital.
To enable hospitals to plan for staff levels and patient levels as accurately as possible, a specific date was chosen as your ‘expected date of confinement.' This became the day you could expect to be going into hospital and staying there.
All of your domestic arrangements were then planned around this day, such as child care for other children and someone to look after your house and husband in your absence.
10 Doctors Plan Their Holidays
As people began to move away from the automatic medical management of pregnancy and birth and look for more natural care, the concept of confinement became seen as old fashioned. Women who had given birth and, along with their babies, had no medical care needs, were able to leave the hospital after shorter and shorter periods until it became usual to leave the same day as the birth if you wished to.
However, as the use of a hospital confinement for mother and baby fell away, the concept of a due date persisted, and although it is a helpful estimate of when the baby will arrive, it has become a tool for some medical staff.
Some doctors like to plan ahead, and if their patient is not delivered on the due date, that woman may be pressured into an induction, not for medical reasons but for logistical and planning reasons.
9 An Old German Guy Does The Calculation
An average pregnancy is said to last for 38 weeks from the date of conception and 40 weeks from the time of the first day of your last period. That is why sometimes you will hear that a pregnancy lasts 264 days and sometimes you will hear it is 280 days. The first is the average time from conception and the second the average time since the first day of your last period.
To work out your due date, subtract three months from the first day of your last period and add seven days. This will be the date your baby is due on. For example, if the first day of your last period were August 1st you would take away three months which takes you to May 1st and add seven days to get the 8th of May. This is called Naegele's rule after German obstetrician Franz Naegele.
8 Basing Bad Information On Bad Information
Why do we use 40 weeks as the benchmark if so few babies actually arrive on that date? Shouldn’t we take a look at the dates people actually deliver and find out what is the most likely average?
The reason for using 40 weeks will probably surprise you.
Naegele's rule was created by a botanist named Harmanni Boerhaave in 1744. Boerhaave based his system on information in the Bible that said human gestation lasts for ten lunar months or forty weeks. Naegle publicized this method, and it became the standard by which every pregnancy was measured.
However, a lunar month is not four weeks or 28 days; it is actually 29.53 days which, using the Bible reference, is 295 days, 15 days longer than the due date suggested by the Naegle rule.
7 The Odds Are One In Twenty
Only 5 percent of babies arrive on their due date but 80-85% of women deliver their babies within seven days of their due date, and the remaining 10-15% of babies are born outside of this time period.
However, these figures include only what are considered uncomplicated pregnancies and deliveries, so all women who go into premature labor are excluded from these figures, and any women who were induced either before or after their due date are also excluded.
There are also pregnancy length variations in such areas as maternal age, race and even the gender of the baby. Women under 30 tend to have slightly longer pregnancies as do Caucasian women and boys tend to bake a bit longer than girls.
6 Early Not Premature
Having an inaccurate due date, or focussing on the due date can cause lots of anxiety, especially if your labor begins before you are expecting it to. The thought of delivering your baby early and it having possible health implications can be terrifying, but these fears are often unnecessary because you are focussed on the due date as the “fully cooked” point.
Only babies born at an estimated gestational age of 36 weeks and six days or before are considered premature and depending on how early they are born; medical intervention may take place to try and slow delivery or administer drugs to help the baby's lungs mature.
If your baby is born between 37 and 38 weeks and six days a baby is considered ‘early term.'
5 Late, Not Postmature
The opposite is true at the other end of the due date scale. Once your due date comes and goes without any action, you can start to become excessively anxious, worrying about the health of your baby and causing each day to stretch from 24 hours to 579 hours.
No time passes as slowly as the time after your due date, but multiple studies have shown that the average pregnancy, if left alone, will last until 41 weeks and there is no increased risk to mother or baby for leaving the pregnancy to progress to this stage.
However, many women are pressured into trying induction as soon as their due date arrives, without giving nature time to take its course. This can cause unnecessary worry, pain and suffering, all because of a fixation on the due date.
4 Everyone Rides Their Menstrual Cycle Differently
Naegele's rule assumes a woman has a regular 28-day menstrual cycle, that she ovulates on day 14 and that the egg is fertilized on the same day, but there are many variations to this.
Women can have a cycle that is anywhere between 20 and 40 days, and some have cycles that vary with each and every month. On top of this you cannot always assume that you have ovulated on a particular day in your cycle, it is generally around the midpoint but can occur at any point.
Finally, you cannot even assume your date of conception (unless you have had IVF) because sperm are sturdy little swimmers and can hang out inside of you for up to four days, ready to fertilize an egg when you least expect it.
3 Ultrasound Dating
The most accurate way of dating a pregnancy is through a fetal ultrasound scan, but, as with everything else, this is not cut and dried.
The earlier in your pregnancy you have a scan, the more accurate the estimated age of your baby will be. If you have a scan during the first trimester and the due date is different to your ‘period’ due date, it is possible your medical care provider may revise your timings and go with the ultrasound dates.
The later in pregnancy you perform an ultrasound the less accurate you can be using the results to date the pregnancy because every baby grows and develops at a different rate. We are all pretty much the same size at six weeks, but by 16 weeks some of us are bigger than others.
2 Cervical Length Scan
New research has shown that a transvaginal ultrasound of the cervix (the one where they insert the magical ultrasound wand up into your lady bits) to measure the length may be able to predict when a woman is likely to go into labor.
Researchers found that when the cervix measured more than 30 millimeters at a woman's due date, she had a less than a 50 percent chance of delivering within seven days. But when the cervix measured 10 mm or less, the mom-to-be had more than an 85 percent chance of delivering within seven days.
The downside to this is that it still does not give an accurate date, just a likely window for labor to begin and it involves expensive, invasive procedures for little real benefit. A physical exam can do much the same thing and has the same level of accuracy.
1 How To Cope
Easier said than done, I know, but as you approach your due date and then watch it disappear in the rearview mirror, try not to fixate on that date.
Making a list of small things you can treat yourself to for every day you go past the big day can help change the focus from when the baby will come to whether or not you will get a haircut, if only for a few moments.
Place a message on your phone telling everyone that no, the baby isn’t here yet, and that you will let them know when it is, and then stop answering their calls.
Finally, you can set up some at home simple date nights for you and your partner or friends. Treat yourself to a great movie, some unhealthy snacks and a foot massage from someone you love. It may be your last chance for a while.
Sources: FearFreeChildbirth.com, FitPregnancy.com, DoulaMoma.com, American College of Obstetricians and Gynecologists (ACOG), American Institute of Ultrasound in Medicine, The Society for Maternal-Fetal Medicine