How To Tell If Your Due Date Is Wrong

Throughout my pregnancy, I've received ii different due dates — one came from my very commencement ultrasound, when my baby was barely the size of a blueberry, the appointment that was then subsequently stamped on my record as "the" due engagement.

But then there was a 2d date, the one that showed upwardly on my adjacent couple of ultrasound scans. This date was a few days before. It's too the date that I prefer, non but because I'm now 38 weeks pregnant and gear up to go this babe out, simply because information technology matched the engagement I'd calculated on my own using information I looked up.

But ... which one should I believe? And how much does it really matter? Afterwards all, as many moms know, due dates are just educated guesses.

How are due dates calculated?

Traditionally, estimated due dates are calculated by taking the commencement date of a woman'south last menstrual period and adding a year, subtracting three months and calculation 7 days, a method known as Naegele's rule.

"If you're a woman whose period is like clockwork, it'south pretty accurate," Dr. Tamika Auguste, MD, an OB-GYN at MedStar Washington Infirmary Center in Washington, D.C., told TODAY Health.

But that method doesn't business relationship for irregularities in a woman's menstrual wheel — if she has a longer or shorter bike than 28 days or any variability with ovulation, for example. That'south why the American College of Obstetricians and Gynecologists recommends doctors utilise ultrasound measurement in the offset trimester to establish an estimated due date.

The most accurate way to date a pregnancy is with an ultrasound done between half-dozen weeks and 8 weeks, vi days, co-ordinate to Dr. Michael Cackovic, MD, an OB-GYN with The Ohio State Academy Wexner Medical Center.

"The reason why is in that location's very little variation that can be detected in a measurement from that time," he said. "Pretty much all pregnancies are equal at that stage."

As a woman's pregnancy progresses, fetuses develop at different rates, which is why an estimated due date from an ultrasound measurement during the second trimester is less authentic. (And why I probably shouldn't be taking my 2d "due appointment" very seriously.)

Equally much every bit engineering has improved, this is all still an imperfect science.

"Ofttimes we get a due date based on the terminal menstrual period and and then exercise a sonogram and in that location'due south a discrepancy we have to address," Auguste added. "If it's all inside a calendar week, it's consistent. One time you go by virtually five or six days, then you lot take to first considering that your dates really may be off."

How reliable is my due date?

Even in one case your doctor has established a due date, there's no guarantee that your infant will come that day. In fact, simply 6% of women deliver on their due engagement, Cackovic said.

I tell patients that really, your due date is a date in the eye of almost a calendar month-long menses of time that you could have your baby.

Dr. Michael Cackovic

"The reality is that about 70% of women will accept their baby within 10 days of their due date," he said. "I tell patients that really, your due date is a date in the middle of almost a month-long period of fourth dimension that you could have your baby."

Nearly x% of babies in the U.S. were born earlier 37 weeks of gestation in 2017, according to information from the Centers for Disease Control and Prevention, while 26% were built-in between 37 and 38 weeks and 57% were born at full term between 39 and 40 weeks. Some babies arrived later the due engagement, as well: another 6% of babies were built-in in week 41 and less than ane% at 42 weeks.

Are there signs my infant will come up early ... or late?

There are many signs that labor is coming: The neck softens, a woman may feel that her infant has "dropped" lower in the pelvis or she may experience what's known equally "bloody show," discharge that contains mucus and blood.

While these are all signs labor will happen — eventually — there's simply no way to know when, exactly.

"The bottom line is we only don't know what starts labor," Cackovic said. "People ask me this all the fourth dimension. The reality is that it'due south some complex mechanism between the baby's encephalon, the mom's brain and the placenta and we oasis't figured it out all the same."

There are some rules of pollex that OB-GYNs follow, though.

"Women who have had multiple babies typically deliver earlier with each subsequent pregnancy," said Dr. Shannon Clark, MD, a professor of maternal-fetal medicine at the Academy of Texas Medical Co-operative at Galveston and the founder of BabiesAfter35.com. "Beginning-fourth dimension moms typically go to their due date in an otherwise uncomplicated pregnancy."

What about routine cervical checks?

Effectually week 36 or 37 of a woman's pregnancy, some doctors will begin to offer cervical checks at appointments, to run into if a woman's cervix has started to amplify (open up) and efface (thin out).

"Start-time moms typically efface offset, and women who have had more than one commitment typically dilate first," Clark said. "Unfortunately, this does not really tell us when she will go into labor. What we as providers are looking for is some change in the cervix, whether in dilation or effacement, so we volition know things are progressing in the right direction."

Some doctors may not recommend routine checks, and some women may choose to opt out of them, because while it can exist tempting to have the information, being dilated or effaced doesn't tell exactly when the infant's going to come.

"I don't check anybody'south neck unless they ask me to, or if they're contracting," Cackovic said. "Medically, there'south just no reason to exercise it."

While there's no shortage of tips to kick-start labor available on the internet, Auguste stressed that it's important to talk to a doctor about the signs of labor before trying any natural induction methods.

"A lot of the data out there is one-time wive'south tales or hearsay, so you really need to have that chat with your provider," she said.