Is it possible to miscalculated due date

The little one, especially—she showed up a mere 30 minutes before my scheduled induction, 11 days after the day she was clinically expected to arrive. I am not alone. Assigning a due date takes several factors into account: last menstrual period as a proxy for the assumed day of ovulation, size of the baby at various stages assessed via ultrasound. A study compared these traditional methods in the cases of nearly 20, births.

The researchers found that precise prediction is basically impossible. Regardless of which method they used to determine estimated Date of Birth, the actual Date of Birth showed considerable variation between babies up to 2 weeks before, and 2 weeks after. Even with the earliest ultrasound, between 11—14 weeks when the fetus is lime-sized, the size of said lime appears to vary just enough to screw up any degree of predictability.

In this study , researchers found that gestation lengths for normal pregnancies can vary up to 5 weeks. The researchers in this study knew exactly which day the little egg popped out of the ovary and started its journey to becoming a human.

No guessing on last period or assuming ovulation date. It is common for each ultrasound throughout pregnancy to predict a different due date. Earlier ultrasounds are more accurate in terms of predicting the due date, so that's why doctors will usually use the dates and measurements from the first ultrasound of the pregnancy as a reference. As pregnancy progresses, the accuracy of an ultrasound for predicting due dates decreases. Between 18 and 28 weeks of gestation, the margin of error increases to plus or minus two weeks.

After 28 weeks, the ultrasound may be off by three weeks or more in predicting a due date. Thus, later in pregnancy, ultrasound measurements are more valuable for evaluating the baby's growth over time compared with earlier measurements than they are for predicting a due date.

Get diet and wellness tips to help your kids stay healthy and happy. Diagnostic accuracy of ultrasound above and below the beta-hCG discriminatory zone. Obstet Gynecol. Estimating the date of confinement: Ultrasonographic biometry versus certain menstrual dates. Am J Obstet Gynecol. Your Privacy Rights.

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By clicking "Subscribe" you agree to our Terms of Use. We'll be in touch every so often with health tips, patient stories, important resources and other information you need to keep you and your family healthy. What can cause your due date to be wrong? Moms2B: Reducing infant mortality in central Ohio and beyond Learn how Ohio State is tackling infant mortality rates from multiple angles, using research, treatment programs and community outreach to create a better future for all pregnancies and babies.

What factors increase the odds of having twins? But if you're looking for more clarity, here are five indicators that you might deliver earlier or later than your original due date suggests. Pregnancies can either be confirmed with a doppler heartbeat monitor or a first trimester ultrasound , according to What to Expect. If you have an ultrasound, and the ultrasound-determined due date is more than seven days apart from your menstrual-cycle determined due date, your OB will defer to the ultrasound date, according to the same What to Expect article.

When you go in for check-ups, your OB might measure something called " fundal height ", which is the distance from your pubic bone to the top of your uterus, according to The Bump. Your fundal height typically syncs up with how far along you are, so for example, if you're 32 weeks pregnant, your fundal height will be close to 32 centimeters. However, if your fundal height is more than two centimeters off in either direction, your OB might order an ultrasound to determine if your due date is off, The Bump explained.