Inaccurate dating of pregnancy

The timing of certain tests, the monitoring of the baby's growth, and the correct diagnosis of premature labor, or being truly "overdue," postdates , as well as many other situations that arise in the course of a typical pregnancy, all depend on a correct determination of the EDC for appropriate management. In the past, the EDC was calculated by using Naegele's Rule, which determined the date by subtracting 3 months from the 1st day of the last period and then adding 7 days. In fact, when a woman who has very regular, "textbook" 28 day cycles presents for prenatal care, this often turns out to be the correct EDC more often than not. Other information used to calculate the gestational age, or the number of weeks and days from the first day of the last menstrual period LMP , includes the size of the uterus on pelvic bimanual examination. However, it is extremely common to encounter patients who have irregular or infrequent menstrual cycles, or have fibroid tumors that cause their uterus to feel enlarged on pelvic exam, or who conceive shortly after a pregnancy ends without ever actually having had a period after the last pregnancy , or who got pregnant while taking birth control pills, and these situations often render the above methods useless and misleading when trying to figure out a reliable EDC.

3 reasons why your due date is wrong

The current way we measure "due dates" is inaccurate at best. Unless you know the day you ovulate and the day you conceive, as well as the length of your cycle, and calculate it yourself, chances are your due date is wrong -- in fact, it can be WAY wrong. Most are off by an average of two weeks. I think most moms know of the March of Dimes -- they're a non-profit organization dedicated to the prevention of premature and still births, as well as the leading research in care of premature babies.

Right now, they're working with 40 North Carolina hospitals to prevent premature birth by preventing unneeded inductions -- and their message? Pregnancy is uncomfortable and at times, downright miserable, but you need to stick it out, and your doctor needs to refuse your induction unless it's medically necessary. Well, except for the fact that their goal is to make sure that your baby is as healthy as possible, and if that means you have to be pregnant for two to three more weeks, then they're telling you -- and your doctor -- that that's what you need to do.

With our incorrect way of looking at due dates, that means if you choose to induce without medical reasons at "38 weeks," your baby could be 36 weeks gestation -- and therefore be preterm and even require time in the NICU. The assumption is that you have a day cycle, ovulate on day 14, and bleed for 5 days. Not everyone does. Call this TMI if you will, but my cycle is 33 days and I ovulate on day 18 -- so when my doctor insisted my daughter's due date was July 5, I kept reminding them I was not a cookie-cutter human -- my due date was actually July She was 38 weeks, 3 days when she was born, though they still called it 39 weeks on the dot.

Every time they mentioned the due date they had written down, I corrected them. Because while it ended up not mattering, what if I'd hit 41 or 42 weeks by their calculations, when they were wrong? They'd have pushed induction , despite the fact that proper calculation shows that they were assuming she was almost a week ahead of her true gestational age.

But I digress That extra weeks makes a huge difference. Babies born even just two weeks early have higher rates of breathing problems, jaundice, feeding problems, temperature regulation issues, and delayed brain development. Not to mention induction before 39 weeks substantially increases the risk of c-section, which has dangers to the mother and child all its own, so it's not just your baby who can seriously suffer from an unneeded induction and premature birth. The March of Dime's efforts with these hospitals has shown a drastic reduction in premature births and c-sections That's pretty huge!

I hope that their success in North Carolina continues and sets an example and standard for hospitals across the country, so we can eliminate elective inductions. After all, every mom wants her baby to be as healthy as possible from the get-go, and after weeks of being pregnant, and decades of life ahead for you and your child, a couple more weeks really is absolutely nothing in the grand scheme of things, but can cause a lifetime of differences.

Are you concerned about your "due date"? What do you think of this news from the March of Dimes? Image via notorious d. Your Due Date Is Wrong. Christie Haskell September 20, at 8: I know, I know That's a lot to risk to not be pregnant for just two more weeks, isn't it?

Had a pregnancy ultrasound that doesn't match your Estimated Due Date (EDD)? MFM mums share their stories plus expert sonographers explain why it. To assess associations between discrepancy of pregnancy dating .. between methods may reflect an erroneous EDD estimated by LMP;.

The current way we measure "due dates" is inaccurate at best. Unless you know the day you ovulate and the day you conceive, as well as the length of your cycle, and calculate it yourself, chances are your due date is wrong -- in fact, it can be WAY wrong. Most are off by an average of two weeks. I think most moms know of the March of Dimes -- they're a non-profit organization dedicated to the prevention of premature and still births, as well as the leading research in care of premature babies.

Pregnancy math can be a little murky. After all, unless you went the IVF-route, your physician has no way of knowing the exact time of conception.

Tryon St. Charlotte, NC N. Davidson St.

Accuracy of Ultrasound in Dating your Pregnancy

Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. A Nature Research Journal. In conclusion, especially, large negative discrepancy was associated with increased risks of adverse perinatal outcomes.

Women's Health Care Physicians

A dating scan is an ultrasound examination which is performed in order to establish the gestational age of the pregnancy. Most dating scans are done with a trans-abdominal transducer and a fullish bladder. If the pregnancy is very early the gestation sac and fetus will not be big enough to see, so the transvaginal approach will give better pictures. Dating scans are usually recommended if there is doubt about the validity of the last menstrual period. By 6 to 7 weeks gestation the fetus is clearly seen on trans-vaginal ultrasound and the heart beat can be seen at this early stage 90 to beats per minute under 6 to 7 weeks, then to beats per minute as the baby matures. Ultrasounds performed during the first 12 weeks of pregnancy are generally within 3 - 5 days of accuracy. The most accurate time is between 8 and 11 weeks gestation. This is because the fetus is growing so quickly that there is a big difference in size from week to week. However, the accuracy of the ultrasound examination is always dependent on the skill of the sonographer and the quality of the equipment.

MFM mums share their stories plus expert sonographers explain why it happens and what to do if you're told your due dates are wrong. By Rachel Mostyn.

NCBI Bookshelf. John A.

How Doctors Date Pregnancies, Explained

An ultrasound can help you determine how far along you are in your pregnancy. Before you consider abortion or seek an abortion clinic, it is important to know how many weeks pregnant you are the gestational age. Even when you can remember when your last menstrual period began, ultrasound can still be more accurate than relying on your last period date alone. The American College of Obstetricians and Gynecologists state the following: Our ultrasounds are performed by licensed ultrasound technicians under the direction of obstetricians. We can come along side you to give you the information you need about your pregnancy to make an informed and empowered decision about abortion. Are you thinking about having sex or have you had sex already? What are your odds of getting pregnant if you use condoms? Condoms are the most common type of birth control. There was no way to stay in denial any longer. That nausea and extreme fatigue she had been feeling could have just been the flu.

Your Due Date Is Wrong

The thing is, because the date carries such meaning to us, we hang everything on it, and rightly so. We start planning, things like…. Yes, I kid you not! There are other due date calculation methods that exist that are based on science and research , but these tend not to be used. Crazy I know! Some women know this information. I had no idea about my ovulation cycle when I found out I was pregnant for the first time.

Can your pregnancy scan give the wrong due date?

Every pregnant woman wants to know her due date , and a due date that is calculated from her last menstrual period with a due date calculator often doesn't match the due date that is estimated by her first ultrasound also known as a sonogram. During an ultrasound, a technician will spread a warm gel over the lower part of your abdomen and then press a tool called a transducer against your belly to examine your fetus using sound waves. An image of your fetus will appear on an accompanying computer screen and while looking at this image, the technician will take some standard measurements from different angles and listen for a heartbeat. Don't worry: This type of exam is painless and risk-free, and seeing your baby for the first time will likely be an enjoyable experience. Naturally, one of the most common questions asked about ultrasound accuracy is: Just how accurate are the due dates that are predicted by an ultrasound?

Ultrasound Accuracy for Predicting Due Dates

This cross-sectional study included consecutive pregnant women receiving antenatal care at two tertiary health institutions in Enugu, Nigeria, from January 1, to March 31, The mean age of the women was Most ultrasound scans The majority of the respondents The worrisome confidence in ultrasound scan dating is a challenge to the prevention of prolonged pregnancy and its complications in our environment.

How accurate are dating ultrasounds at 7 weeks

Pettker, MD; James D. Goldberg, MD; and Yasser Y. This document reflects emerging clinical and scientific advances as of the date issued and is subject to change. The information should not be construed as dictating an exclusive course of treatment or procedure to be followed. Accurate dating of pregnancy is important to improve outcomes and is a research and public health imperative.

Want to learn more about Bloomlife? See how it works. 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:

How can I know when I conceived?
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