As soon as you find out you’re pregnant, the next thing you’ll want (besides prenatal care) to know is your baby due date. The answer on when your baby is due? It depends.
Pregnancy doesn’t run on a set clock, but average pregnancies last 40 weeks (280 days) – which deviates slightly from the “nine months” that you most often hear. Birthing can range from a couple of weeks before to a couple of weeks after your predicted due date.
The bottom line is that the baby shows up when it’s ready to (unless a medical intervention is needed to make it happen).
What Should Know About Baby Due Date Myths
Why the Baby Due Date Is Important
Even though your due date won’t be set in stone, calculating it is helpful to protect in cases of very early or very late babies. Just 4% of women deliver on their calculated due date and up to 10% will deliver after the calculated due date. Once a pregnancy reaches 42 weeks, special considerations must be taken to ensure a safe delivery for mother and child. Prior to 37 weeks, most care providers will attempt to slow or stop pre-term labor to allow the baby time to develop.
How Baby Due Dates are Calculated
Before ultrasound came into common practice, Naegele’s rule (also called Nagel’s rule) was used to calculate the due date. It is based on the date of the last menstrual period. Click here to see a Naegele due date calculator. It isn’t highly precise because it assumes a 28 day menstrual cycle and day 14 ovulation. Ultrasounds are much more accurate in determining gestation stage and due date. Early in pregnancy, babies grow at consistent rates so measurements can accurately predict conception date.
What Affects Pregnancy Due Date Calculation?
After 20 weeks of gestation, fetal growth can vary greatly so it’s important that an ultrasound be performed as early as possible when pregnancy is suspected. When calculating due dates with a Nagel method, longer or shorter menstrual cycles, irregular periods or erratic ovulation can throw off the calculation. First trimester ultrasound dating offers the most accurate due date calculation and is the preferable method, but it won’t be spot on.
A first trimester ultrasound due date is the most accurate. For an ultrasound taken in the second trimester, if the Nagel due date and ultrasound date are more than 10-14 days apart, the ultrasound date should be used. You may have calculated a date based on your last period, you may be told one date by your care provider then later be given another date. The important thing is that you get the best prenatal care that includes monitoring fetal development to ensure you deliver a strong, healthy baby.
What Affects Delivery Date?
Even if you’ve been given a due date, certain circumstances need to be considered to determine if intervention is needed to ensure a safe delivery for mother and child. A new study by the National Institute for Environmental Health found that normal pregnancies can vary as much as five weeks in length. Their study showed that 80% of babies arrived either two weeks before or two weeks after the estimated due date.
While the later you go after your due date, the higher certain risks are, including stillbirth, many women delivery safely at 42 weeks or later. The bottom line from the study was that every pregnancy should be taken on a case-by-case basis that considers age of the mother (older mothers tend to have longer pregnancies), prior births and health of mother and fetus. To help your care provider most accurately calculate due date, offer info about your cycle length and when you think you conceived.
The Natural Childbirth Experience
At Austin Area Birthing Center, we help moms to be enjoy a natural childbirth experience in a luxury birthing environment for one affordable fee. Austin ABC is an in-network provider for most insurance carriers and take care of all your lab work, routine prenatal care and labor and delivery. Also included in our fee is an extensive roster of classes including prenatal and postpartum yoga, breastfeeding and diapering classes, birthing refreshers for prior parents and baby love classes for both mom and dad.
You can choose from our Duval Road or William Cannon Drive facilities or enjoy our custom birthing services at Seton Medical Center in Central Austin. Starting in Spring, we will open a third facility in Williamson County. Click here to contact us, set up a tour and find out more about the award-winning birthing services at Austin Area Birthing Center.
