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The Unpredictability Of Due Dates

Your due date is anything but predictable. In fact, it is totally unpredictable.

Every birther (birthing person) is a unique human with a unique story, carrying a unique person, who will be born on a unique due date. Each birth unfolds uniquely, and the individual process is special and beautiful.

Calculating due dates is an effective tool for measuring progress and understanding when help is needed. In most births, help is not needed rather trusting the process is fundamental.


Calculating your due date

Your due date is calculated by adding 280 days or 40 weeks to your LMP or last menstrual period. This is based on a 28-day cycle.  If your cycle is not 28 days, this will mean that your due is less accurate for you.

So, many providers will use an early 1st-trimester ultrasound for dating.  This ultrasound is considered the most accurate dating based on measuring the size of the fetus and the gestational sack.  Then your provider can tweak or adjust your due date accordingly.

But even if your due dates match, your baby may not show up on time.  I like to recommend that new mothers look to their maternal line for family histories. If there is a strong pattern of the women going early or late then there is a good chance that you will follow your family’s gestation period.

If this is not your first birth, then your body is more likely to give birth around a similar time with each child.  Within 3 days either way. Remember this is not a guarantee. Exceptions may happen due to inductions, the baby’s health, your health, and including if either baby was misdated.


Preterm, early term, term, and late-term dates

Preemie, preterm, term, and post-term are typical medical jargon concerning when the baby was born in relation to their due date, called an EDD- estimated due date. What do all these terms mean?

  • Preemie: born before 37 weeks
  • Early term: born 37-38 weeks
  • Term: born 39-40 weeks
  • Post-term: born 41-42 weeks

About 11 percent deliver prematurely. Experts aren’t sure why some people go into labor early. Possible risk factors include carrying multiples (twins or triplets), health concerns, cervical issues, or having an unusually shaped uterus. Furthermore, there may also be a connection between preterm labor and infection such as bacterial vaginosis. Also, your child and their health can play a role in when they are born.


So, when will my baby come?

Did you know, that only 5% of all babies are born on their due date? Over 50% are born within a week of the due date and 90% within 2 weeks. Only 10% of all babies are born post-term, past 42 weeks.

Although you cannot control when your baby will arrive, you can reduce the risk of an early or late baby by taking a few special steps:

  • Stop smoking and recreational drugs
  • Limit alcohol, wine, and caffeine
  • Exercise 30 minutes or more a day
  • Eat a healthy diet, avoid prepackaged foods
  • Take prenatal vitamins during the entire pregnancy
  • Get plenty of sleep
  • Stay hydrated
  • Go to all your prenatal check-ups
  • Reducing daily stress

If you have any concerns about your individual risk of a pre or post-term pregnancy, discuss them with your practitioner at your next prenatal visit!