Pregnancy Due Dates Calculator. Calculates pregnancy dates, forward from last period or backward from due date. Enter last menstrual period (LMP), current gestational age (GA), OR expected due date to determine the other two, plus estimated date of conception. Patients who are pregnant or may be pregnant.
The estimated date of delivery(EDD), also known as expected date of confinement[1], and estimated due date or simply due date, is a term describing the estimated delivery date for a pregnantwoman.[2] Normal pregnancies last between 37 and 42 weeks.[3]
- 2Estimation methods
- 2.2Estimation of gestational age at childbirth
- 2.2.2Standard 280 days
- 2.2Estimation of gestational age at childbirth
Origins of the term[edit]
Confinement is a traditional term referring to the period of pregnancy when an upper-class, noble, or royal woman would withdraw from society in medieval and tudor times be confined to their rooms with midwives, ladies-in-waiting and female family members only to attend them.[4] This was believed to calm the mother and reduce the risk of premature delivery. Except in threatened pregnancies (for example, in pre-eclampsia), 'lying-in' or bedrest is no longer a part of antenatal care.
Estimation methods[edit]
Due date estimation basically follows two steps:
- Determination of which time point is to be used as the origin for gestational age. This starting point is the woman's last normal menstrual period (LMP) or the corresponding time as estimated by a more accurate method if available. Such methods include adding 14 days to a known duration since fertilization (as is possible in in vitro fertilization) or by obstetric ultrasonography.
- Adding the estimated gestational age at childbirth to the above time point. Childbirth on average occurs at a gestational age of 280 days (40 weeks), which is therefore often used as a standard estimation for individual pregnancies.[5] However, alternative durations as well as more individualized methods have also been suggested.
Estimation of gestational age[edit]
According to American Congress of Obstetricians and Gynecologists, the main methods to calculate gestational age are:[6]
- Directly calculating the days since the beginning of the last menstrual period
- Early obstetric ultrasound, comparing the size of an embryo or fetus to that of a reference group of pregnancies of known gestational age (such as calculated from last menstrual periods), and using the mean gestational age of other embryos or fetuses of the same size. If the gestational age as calculated from an early ultrasound is contradictory to the one calculated directly from the last menstrual period, it is still the one from the early ultrasound that is used for the rest of the pregnancy.[6]
- In case of in vitro fertilization, calculating days since oocyte retrieval or co-incubation and adding 14 days.[7]
Estimation of gestational age at childbirth[edit]
Childbirth on average occurs at a gestational age of 280 days (40 weeks), which is therefore often used as a standard estimation for individual pregnancies.[5] However, alternative durations as well as more individualized methods have also been suggested. There is in any case considerable variation among individual pregnancies.
Variability[edit]
Distribution of gestational age at childbirth among singleton live births, given both when gestational age is estimated by first trimester ultrasound and directly by last menstrual period. About 80% of childbirths occur between 37 and 41 weeks of gestational age, with a somewhat more narrow span when based on first trimester ultrasound.[8]
Given that these gestation lengths are only estimates of an average, it is helpful to consider gestation time as a range of dates rather than as a single 'due date'. The median is merely a guideline for the day at which half of all births occur earlier, and half of all births occur later. Births rarely occur on a due date, but they are clustered around due dates.[9] A study of singleton live births in the US came to the result that childbirth has a standard deviation of 14 days when gestational age is estimated by first trimester ultrasound, and 16 days when estimated directly by last menstrual period.[8]
Standard 280 days[edit]
Naegele's rule[edit]
Naegele's rule is a standard way of calculating the due date for a pregnancy when assuming a gestational age of 280 days at childbirth. The rule estimates the expected date of delivery (EDD) by adding a year, subtracting three months, and adding seven days to the origin of gestational age. The result is approximately 280 days (40 weeks) from the start of the last menstrual period. Another method is by adding 9 months and 7 days to the first day of the last menstrual period.
Naegele's rule is named after Franz Karl Naegele, the German obstetrician who devised the rule. Naegele was born July 12, 1778, in Düsseldorf, Germany. In 1806, Naegele became ordinary professor and director of the lying-in hospital in Heidelberg. His Lehrbuch der Geburtshilfe, published in 1830 for midwives, enjoyed a successful 14 editions.
Example:
LMP = 8 May 2009
LMP = 8 May 2009
- +1 year = 8 May 2010
- −3 months = 8 February 2010
- +7 days = 15 February 2010
280 days past the start of the last menstrual period is found by checking the day of the week of the LMP and adjusting the calculated date to land on the same day of the week. Using the example above, 8 May 2009 is a Friday. The calculated date (15 February) is a Monday; adjusting to the closest Friday produces 12 February, which is exactly 280 days past 8 May. The calculation method does not always result in 280 days because not all calendar months are the same length; it does not account for leap years.
Mobile apps[edit]
Mobile apps essentially always give consistent estimations compared to each other and correct for leap year, while pregnancy wheels made of paper can differ from each other by 7 days and generally do not correct for leap year.[10]
Other suggested durations[edit]
- 276 days for both ultrasound-estimated and LMP-estimated gestational age in a US study of 1867 singleton live births.[8]
- 281 days after LMP with a standard deviation of 13 days, was the result of a population-based study of 427,581 singleton births in Sweden.[11]
- 281 days after LMP for first-time mothers and 280 days for all others were the medians found by a 1995 American study of 1,970 spontaneous births. Standard deviation was 7–9 days.[12][13]
- 282 days after LMP was recommended for cases where LMP is the only known factor, in a study of 17,450 patients combining LMP and ultrasound measurement techniques.[14]
- A median of 288 days (274 days from the date of ovulation) for first-time mothers and 283 days (269 days from the date of ovulation) for mothers with at least one previous pregnancy was found by a 1990 study of 114 white, private-care patients with uncomplicated pregnancies and spontaneous labor. The authors suggest that excluding pregnancies involving complications (that often lead to pre-term deliveries) accounts for the longer periods.[15]
Individualized[edit]
- Multiple linear regression models have also been developed that account for maternal parity, age, and race, all which have been found to be important variables determining the length of human gestation. Multiparous women, women aged less than 19 or more than 34 years, and black women have been found to have shorter gestations than primiparous women, women aged 19 to 34 years, or white women.[16]
References[edit]
- ^A Concise Guide to the Employment Ordinance. Labour Department, Hong Kong Government
- ^'Definition of Estimated date of confinement (EDC)'. MedicineNet, Inc. Retrieved 13 January 2010.
- ^Durham, Janelle (2004). 'How accurate is your Due Date?'. www.transitiontoparenthood.com. Retrieved 13 January 2010.
- ^'Childbirth in Medieval and Tudor Times'. The Tudor Society. Retrieved 31 December 2017.
- ^ ab'Calculating Your Due Date'. Healthline Networks, Inc. Archived from the original on 21 December 2009. Retrieved 13 January 2010.
- ^ abObstetric Data Definitions Issues and Rationale for Change - Gestational Age & TermArchived 2013-11-06 at the Wayback Machine from Patient Safety and Quality Improvement at American Congress of Obstetricians and Gynecologists. Created November 2012.
- ^Tunon, K.; Eik-Nes, S. H.; Grøttum, P.; Von Düring, V.; Kahn, J. A. (2000). 'Gestational age in pregnancies conceived after in vitro fertilization: A comparison between age assessed from oocyte retrieval, crown-rump length and biparietal diameter'. Ultrasound in Obstetrics and Gynecology. 15 (1): 41–46. doi:10.1046/j.1469-0705.2000.00004.x. PMID10776011.
- ^ abcHoffman, Caroline S.; Messer, Lynne C.; Mendola, Pauline; Savitz, David A.; Herring, Amy H.; Hartmann, Katherine E. (2008). 'Comparison of gestational age at birth based on last menstrual period and ultrasound during the first trimester'. Paediatric and Perinatal Epidemiology. 22 (6): 587–596. doi:10.1111/j.1365-3016.2008.00965.x. ISSN0269-5022.
- ^Evaluation of Gestation at eMedicine
- ^Chambliss LR, Clark SL (2014). 'Paper gestational age wheels are generally inaccurate'. Am. J. Obstet. Gynecol. 210 (2): 145.e1–4. doi:10.1016/j.ajog.2013.09.013. PMID24036402.
- ^Bergsjø P, Denman DW 3rd, Hoffman HJ, Meirik O. (1990). 'Duration of human singleton pregnancy. A population-based study'. Acta Obstet Gynecol Scand: 197–207.CS1 maint: multiple names: authors list (link)
- ^Gray, H (1962). 'Duration of pregnancy'. Stanford Medical Bulletin. 20: 24–8. PMID13901307.
- ^H. Kieler; O. Axelsson; S. Nilsson; U. Waldenströ (1995). 'The length of human pregnancy as calculated by ultrasonographic measurement of the fetal biparietal diameter'. Ultrasound in Obstetrics & Gynecology. 6 (5): 353–357. doi:10.1046/j.1469-0705.1995.06050353.x. PMID8590208.
- ^Nguyen T, Larsen T, Engholm G, Møller H (1999). 'Evaluation of ultrasound-estimated date of delivery in 17,450 spontaneous singleton births: do we need to modify Naegele's rule?'. Ultrasound Obstet Gynecol. 14 (1): 23–8. doi:10.1046/j.1469-0705.1999.14010023.x. PMID10461334.
- ^Mittendorf R, Williams MA, Berkey CS, Cotter PF (1990). 'The length of uncomplicated human gestation'. Obstet Gynecol. 75 (5): 929–32. PMID2342739.
- ^Mittendorf R, Williams MA, Berkey CS, Lieberman E, Monson RR (1993). 'Predictors of human gestational length'. American Journal of Obstetrics and Gynecology. 168 (2): 480–484. doi:10.1016/0002-9378(93)90476-Y. PMID8438913.
- ^'Due Date Calculator - When am i due ? - Calculate due date'. absolutedays.com.
Retrieved from 'https://en.wikipedia.org/w/index.php?title=Estimated_date_of_delivery&oldid=918517777'
If you get pregnant on November 16, would you give birth on July 16?
I am not sure when my delivery date will be and confused by the charts above.
As explained in the article, you will subtract three months and add seven days to your last menstrual period. If you mean that your last menstrual period was November 16, then you are expected to deliver your baby on August 23. However, you may also deliver on an earlier or later date, depending on many factors, including, but not limited to the number of times you've been pregnant and reached full-term pregnancy, whether there are any complications, etc.
The answer is no. The normal number of weeks for pregnancy is 40 weeks or about 280 days from your last menstruation period. If a woman gets pregnant, the pregnancy hormones take over preventing a woman to have a menstruation. In regards to your query, if you get pregnant on the 16th of November and you have a normal 28 days menstruation cycle, your estimated date of birth will be on August 23 following the Naegele's Rule.
The Naegele's Rule is the standard method used in determining the estimated date of delivery for women who have a normal 28 days menstruation cycle. The equation in Naegele's Rule is simply deducting three months from the date of your last menstruation then add 7 days and 1 year which you'll come up with the date August 23 which greatly contradicts your estimated date of birth July 16.
See more questions like this: If I fell pregnant on the 9 of February when will I give birth?
Calculation math tricks for pregnancy period: Quick calculation method?
Is there a quick calculation method? I'd prefer something less math intensive.
One of the quickest and most efficient ways in calculating the estimated pregnancy period is the Naegele's Rule. This rule is described in the steps above. It was devised by Franz Karl Naegele, a German obstetrician.
The simple and quick mathematical formula in Naegele's Rule is simply determined using your last date of your menstruation period, deduct three months then add seven days and one year to estimate the date of birth or delivery.
The usual date of birth is approximately 40 weeks or 280 days from the last menstruation period. However, the Naegele's Rule is only efficient in women who have a regular 28-day menstrual cycle.
Last menstruation was on June 28, 2013; what is the expected date of delivery?
I am trying to calculate my delivery date, but the charts are confusing, and I keep getting different results. Can you please help me figure out when my delivery date is?
Your expected date of delivery is April 04, 2014. It is easy to calculate. Follow the formula provided below:
From the date of your last menstruation, which is June 28, 2013, just move three months backward then you will have March 28, 2013, and then add seven days, and you will have April 4, 2013. Add one year, since you will give birth in the year 2014, so your expected date of delivery is April 4, 2014.
Due date is 7/27/14 what is conception date?
I figured out my delivery date, but I am still not sure when the actual conception date is.
According to this information, the conception date is around November 26th or 27th. This is approximately 9 months back from your due date in order to determine the date of conception.
Why is my due date April 4 when my last period was June 28?
I don't understand why my delivery dates are different than my menstrual cycle dates.
This is because the date of your last menstrual is not the date that you became pregnant, the date that determines your due date will be the date of conception or when the sperm entered your egg successfully.
See more questions like this: When is my baby due? How far along am I
My last menstrual date was on the 28th of December. When should I start feeling baby kicks?
Now it's the end of April. Am I not supposed to be feeling the baby kick by now?
You should be expecting to feel that around the 5th or 6th month when your baby has become much bigger. Right now, you are just at the end of your 4th month so you cannot expect to start feeling the baby kick.
I went to the health department and they told me I got pregnant June 28th and now its July 27th and they said I'm 6 weeks?
That doesn't add up is there any way you could tell me why they add two more weeks on?
Healthcare providers usually add two weeks to your conception date because they count the first day of pregnancy as the first day of your last menstrual period. It does not necessarily correlate to the day you conceived. One reason they do this is that many women do not have a 28-day menstrual cycle where they ovulate at day 14. This also takes into consideration that sperm can live in your body for up to a week. They add these extra two weeks when they figure out your due date.
See more questions like this: I am a bit worried, I had unprotected sex on the Oct 9th &10th with my ex, and had unprotected sex on the 13th with my current boyfriend. Now I am worried about the result of the dad. My current boyfriend is mad at me because we were together broke up th
When did I get pregnant? I'm lost and it is causing problems with my partner, went to 2 different hospitals and they have different due dates and timing?
My last period began on June 19th or June 20th for sure, my doctor says I'm about 12weeks and 4days and my due date is around March 26-27, 2015. Now the problem is when I went to go get my ultrasound somewhere else I was told I'm around 14 weeks pregnant and my new due date might be around March 13, 2015. I'm lost I don't know what to believe and it's causing confusion with my partner. I need to know about what time did I get pregnant this is my first and I'm confused. One doctor is telling me one thing and my doctor is saying something different. Is it possible I was already pregnant and had my menstrual cycle still on a regular day
There are a few possibilities that can explain this, but you will need to ask each doctor for clarification. Many doctors add two weeks to your due date, counting the date of conception as the first day of your last monthly period. Ask your doctors if they are going by the date of the ultrasound, or if they are adding days according to your last period. According to WebMD, you cannot have a full, regular period while you're pregnant, but you can have implantation bleeding or light spotting for a few days. Ask your doctor to be sure, and if your partner is having doubts, consider bringing him with you to an appointment so that he can hear the explanation from your doctor.
If my due date is September 7, which month do you think I was pregnant?
I saw my last normal period around November 20 or 25
Assuming you had an average 28 day menstrual cycle with ovulation on day 14, it's likely that you became pregnant in the month of December. Even if you ovulated later, it is still likely that you conceived sometime in December. You'll need to consult with your doctor to be sure.
I don't remember my last period date but I am expected to give birth in April twenty-seventh or from the fifteenth so when did I get pregnant?
When was my conception date or month?
The conception date is 40 weeks before the due date. If your due date is April 27, 2016, and you had an average 28-day menstrual cycle, you likely conceived between August 1 and August 9. If your due date is April 15, 2016, you likely conceived between July 20 and July 28.
See more questions like this: How could I be 8 months pregnant by October, if I had my last menstruation period on April 29,2016 and felt fetal moves in mid-August?
How to calculate EDC using Naegele's rule?
How do I calculate the EDC using Naegele's rule if a woman has an irregular menstrual cycle?
Naegele's rule is not accurate if you do not have a regular cycle, but you can use another method known as Parikh's formula. To use Parikh's formula, add 9 months to the first day of your last period, subtract 21 days, then add the number of days in your average menstrual cycle. If your cycles were different from month to month, average the number of days for the last few cycles. For example, if your last few cycles were 26 days, 33 days, and 29 days, you would add 29 days.
Please help me figure out my delivery date?
My last month when I saw my period was October. The first day of my menstruation was 10th of October, can you please help.
Many healthcare providers count the due date as 40 weeks after the first day of your last period. This would give you an estimated due date of July 17; however, you need to see your doctor to be sure, and the majority of women do not give birth exactly on their dates.
Please, I can't use my pad well, can you teach me and please I started my menses on 20 February, when should I expect it to end?
Menstrual period about females
The average menstrual period lasts between 5 and 7 days. When shopping for pads, choose the correct absorbency level for your flow. Most women have varying flow levels throughout their periods, so you may want to buy pads for both heavier and lighter flow. To use a pad properly, remove the adhesive backing and place it in your underwear. Change your pad every few hours or as often as needed for good hygiene. Don't use a pad longer than 8 hours for sanitary reasons. To dispose of used pads, fold it in half so that only the adhesive side is exposed. Wrap it in a few layers of toilet paper or in the plastic packaging that new pads are wrapped in. You can also put it in a plastic or paper bag. Do not flush a pad down the toilet. Throw it in a lined trash bin, preferably one with a lid to keep pets out of it, or you can put it in a cabinet under the sink. You'll want to dispose of the trash more often when you're on your period.
How do I know if its an implantation bleeding?
I had a heavy 7 day period in May. Then in June, 4 weeks later I had a light 2 day period, which month would I work my pregnancy from
You would factor in the due date using the May menstrual cycle. The June cycle was more like break through bleeding if you became pregnant in the May cycle.
I need to know roughly when I conceived?
My LMP was 15th Feb. My 1st scan said EDD 20th Nov and other 2 19th November - sounds good. Had intercourse on 21st or 22nd cannot remember and then again on March 6th (with protection). According to all the calculation including my LMP and Ultrasound calculation, my conception should be around 26th Feb - 1st March. Please help me determine when had I likely conceived?
The conception date likely occurred from the 21st or 22nd. That does not mean you can completely rule out March 6th but the odds are more in favor of the February dates and not the March 6th.
My impregnated was on July 24. I would like to know the expected date of delivery?
I would like to know the expected date of delivery?
Your due date would be around May 1st if your date of conception was July 24th.
See more questions like this: If some one got pregnant on 24/03/2019 when is delivery?
Why we subtract 3 months from our first date of last menstrual cycle?
I want to know the basic concept why we subtract 3 months and then add 7 days. There not mention about formula basic concept?if I think critically I can not understand and can not satisfy why we add 7 days and why we subtract 3 months?
Using a yearly calendar which is 12 months, you would subtract the 3 months because a pregnancy lasts up to 42 weeks or 9 months. 12-3 = 9
What is the expected date of delivery of a woman whose last normal was 25th September 2017?
What's the Expected date of delivery of a woman with a last Normal menstruation period of 25th September 2017
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If I took in first week of october, when is my due date?
If I took in first week of october, when is my expected date of delivery? Your article actually covered many grounds but I don't see anyone specifically related to mine question
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I really don't understand, can calculate my due date December 1st 2017?
Why are the numbers in blue starts with 8? I really don't get it.
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My wife conceived on 16th March 2018 but deliver a baby on 29th October 2018?
What might be a reason for earlier delivery?. Thanks. She involved in partial accident on early September 2018. I have tried: I have tried to see a doctor but said delivery at week 30 it is possible if she involved in accident but likely the baby can not survive. I think it was caused by: I think because she involved in accident it could be she was shocked and this led to early delivery
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If my lmp was 19 february what will be my date to deliver?
I want to no wen to deliver wen my last lmp was 19 february. What will be my exact date to deliver if my last menstrual period was 19th february 2018
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My last LMT December 27 2018 what is my exact delivery date?
What is my delivery date if its is August 2 2019 , I am very confused this that's way I asking this question for clearing my doubts ? Nothing different I want to know my delivery date that's all
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See more questions like this: If my last date of period is 20 May 2018 then what is my delivery date,and when did I concieve?
When my last flow is 10th of Sept ember when is my Edd?
My last flow was 10th of September, when is my delivery date?
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