Plan due date
Calculate your due date: How to find your baby's due date
Choose a calculation method Last periodConception dateI know my due date
First day of my last period
BabyCenter's Due Date Calculator
Use our pregnancy due date calculator by plugging in either the date of your last menstrual cycle or the date you know you conceived. The calculator will do the rest.
How is my due date calculated?
There are several ways your due date is determined. If you happen to know the day you conceived, you can count 38 weeks from that day to find your due date. (Human gestation takes about 38 weeks.)
But very few expectant moms know exactly when they conceived. Even if you only had sex once during your fertile period, you wouldn't conceive on that day unless you happen to be ovulating. Sperm can live for up to five days inside your fallopian tubes. So, it could be up to five days after you have sex that you release an egg (ovulate) and it gets fertilized by a waiting sperm. That's the day you conceive.
So, without knowing the day of conception, how does anyone determine a due date?
First day of your last period
The most common way to calculate your pregnancy due date is by counting 40 weeks from the first day of your last menstrual period (LMP). And that's how most healthcare providers do it.
If your menstrual cycle length is the average length (28-day cycle), your menstrual cycle probably started about two weeks before you conceived. This explains why pregnancies are said to last 40 weeks instead of 38 weeks.
This method doesn't take into account how long your menstrual cycle actually is or when you think you might have conceived. But generally speaking, women typically ovulate about two weeks after their menstrual cycle starts. And women are more likely to know when their last period started than the day they ovulated.
Conception date
If you do happen to know precisely when you conceived – say, if you were using an ovulation predictor kit or tracking your ovulation symptoms – you can calculate your pregnancy due date based on your conception date.
Just choose that calculation method from the pulldown above and put in your date.
Note: Again, you don't necessarily conceive on the day you have sex.
IVF transfer date
If you conceived through IVF, you can calculate your due date using your IVF transfer date. If you had a Day 5 embryo transfer, count 261 days from your transfer date. If you had a Day 3 embryo transfer, count 263 days.
Can my due date change?
Your healthcare provider might revise your due date if your baby is measured during a first trimester ultrasound scan and found to be much bigger or smaller than expected for gestational age. This is more likely to happen if you have an irregular menstrual cycle length that makes it hard to pinpoint the date of conception.
Your healthcare provider will measure your baby during that ultrasound exam to figure out how far along your baby is and then provide you with a new due date.
What if I already know my due date?
If you already know your due date, you can use this calculator to see your pregnancy timeline.
It will tell you when you'll hit various milestones, and when you may be due for prenatal tests and prenatal visits. You'll also find what your baby's sign and birthstone will probably be and which famous people were born on your due date.
How likely am I to give birth on my due date?
Of course, a due date calculation is always approximate, whether it's from our tool or from your doctor or midwife. Only 1 in 20 women delivers on their due date. You're just as likely to go into labor any day during the two weeks before or after.
Want more information about how the weeks, months, and trimesters of pregnancy are counted? See our pregnancy timing chart.
How soon can I take a pregnancy test?
With all this talk about pregnancy due dates, you may be wondering when you can take a pregnancy test. To ensure you get the most accurate reading, it's best to wait a few days after your missed period to take a pregnancy test.
At-home urine tests measure the amount of hCG (human Chorionic Gonadotropin) present in your body.
If you take a pregnancy test before you miss your period, you may not get an accurate result, despite what some tests advertise.
If you're getting a blood test in your provider's office, you may get results sooner. These tests also measure the amount of hCG in your bloodstream, but they're more sensitive than at-home urine tests. Blood tests may be able to detect pregnancy six to eight days after ovulation.
Read more
- Your pregnancy, week by week
- Your first trimester pregnancy checklist
- Pregnancy Weight Gain Calculator
- Ovulation Calculator
- See all tools
Pregnancy Due Date Calculator – Forbes Health – Forbes Health
Only one in 20 people give birth on their due date, according to the American College of Obstetricians and Gynecologists (ACOG). But knowing your estimated due date is important, as it’s used to track your baby’s growth and provides a timeline for important tests and diagnostics throughout your pregnancy.
You can predict your estimated due date based on simple factors like the first day of your last period.
Pregnancy can come with a lot of unknowns, but your estimated due date doesn’t have to be one of them. Crunch the numbers with our due date calculator to plan for the arrival of your baby.
Due Date Calculator
How to Calculate Your Due Date
Our due date calculator uses the following methods to calculate your due date.
Due Date Based on Your Last Period
This method calculates your due date based on the first day of your last period, assuming a typical pregnancy, on average, lasts 40 weeks (or 280 days) from the first day of your last period. To calculate your due date using this method, you also need to input the average length of your menstrual cycle.
If your menstrual cycle is longer than the average cycle of 28 days, your due date is pushed forward and the amount of time you’re pregnant is reduced. Meanwhile, if your cycle is shorter than the average 28 days, your due date is pushed back.
Due Date Based on Conception
This method calculates your due date based on the date of conception by assuming a gestation period of 38 weeks (or 266 days) from the date of conception.
Now, Kelly Culwell, M.D., an obstetrician-gynecologist and Forbes Health Advisory Board member, notes that the date of conception isn’t always a reliable method for determining your estimated due date. It’s “often incorrectly estimated due to [the] date of intercourse, which can be several days off from [the] actual date of conception based on the sperm’s ability to survive for five days in the reproductive tract,” she says.
Due Date Based on IVF Transfer
If your pregnancy is the result of a successful in-vitro fertilization (IVF) procedure—in which eggs are extracted and fertilized with sperm, with the resulting embryo later transferred to the uterus—you can calculate your estimated due date based on the timeline of the procedure.
- IVF day 3 transfer: If your embryo was transferred to your uterus after three days of embryo growth, this method calculates your estimated due date based on 263 days from your date of transfer.
- IVF day 5 transfer: If your embryo was transferred to your uterus after five days of embryo growth, this method calculates your estimated due date based on 261 days from your date of transfer.
Due Date by Ultrasound
This method of calculation takes into account the weeks and/or days in which you had an ultrasound. It takes the date of your ultrasound, subtracts the number of weeks at which your ultrasound is done and then adds 280.
Not all the methods described above are the same in terms of accuracy, notes Dr. Culwell. “One of the biggest misconceptions that I see is pregnant people thinking that their due date changes if the dating is slightly different on later ultrasounds, or not believing a due date should change if the first trimester ultrasound is different from what is predicted based on their last menstrual period.”
Instead, she says the most accurate method of calculation (aside from IVF transfer dates, which are the most accurate) is an early first trimester ultrasound and certain date of last menstrual period, followed by the date of conception and lastly, a second or third trimester ultrasound.
Early Pregnancy Symptoms
It can be difficult to detect pregnancy without a test, as many of the early signs and symptoms mirror those of your period. The most common early signs of pregnancy include:
- A missed period
- Frequent urination
- Fatigue
- Nausea
- Sore and enlarging breasts
Less common early symptoms of pregnancy include cramping, spotting (or light vaginal bleeding), food cravings or aversions, headaches and dizziness, fluctuating moods and a metallic-like taste in your mouth.
How Long Can You Go Past Your Due Date?
It is typical for a pregnancy to last between 37 and 42 weeks. A pregnancy lasting beyond 42 weeks is considered post-term, which means the pregnancy is past its due date.
Depending on your health care provider, your pregnancy may reach 41 weeks without any intervention. However, doctors will often run tests on people who are 41 weeks to ensure that the baby is active and healthy.
A non-stress test and ultrasound are among the tests a doctor may run on a person who is past 41 weeks pregnant.
Your doctor will look for whether the baby has an adequate amount of amniotic fluid and if the baby is active in the womb. If that is the case, the pregnancy may go on a bit longer until you possibly go into labor on your own. Sometimes, the tests may show the baby is in potential distress, and your doctor may discuss inducing labor.
The risks to both you and your baby increase as a pregnancy reaches 41 to 42 weeks. At this point, your doctor may decide it’s best to induce labor. This is especially true for pregnant people over 40 years old.
Is It Possible for My Due Date to Change?
Typically, an ultrasound is used to confirm your due date (based on your estimated due date calculated from your last menstrual period), and “once a due date has been selected, it does not change no matter how many additional ultrasound exams you may have during your pregnancy,” states ACOG.
Still, ACOG also notes that “subsequent changes to the EDD (estimated due date) should be reserved for rare circumstances, discussed with the patient and documented clearly in the medical record. A pregnancy without an ultrasound examination that confirms or revises the EDD before 22 0/7 weeks of gestational age should be considered suboptimally dated.”
How Likely Am I to Give Birth on My Due Date?
Though due dates can be helpful to give an estimated time of arrival for expecting parents, they are rarely accurate to the day, according to ACOG.
Factors that can contribute to your baby being overdue—or a postterm pregnancy—are often unknown, but can include:
- If this is your first baby
- If you’re carrying a male fetus
- If you’ve had a previous postterm pregnancy
- If you have obesity
Factors that can lead to preterm birth of your baby (birth before 37 weeks) include:
- Your medical history, such as having a previous preterm baby
- Pregnancy complications, including carrying more than one fetus
- Lifestyle factors, including if you smoke
- If you’re under the age of 17 or over the age of 35
How Accurate Are Due Dates?
No estimated due date is ever 100% accurate, and even ultrasound scans aren’t entirely accurate.
However, the ACOG notes that the most accurate method of confirming gestational age is an ultrasound measurement of the fetus or embryo in the first trimester, citing an accuracy of +5-7 days.
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FAQs
How many weeks is a pregnancy?
The majority of pregnancies last between 37 and 42 weeks.
What is an EDD calculator?
An estimated due date (EDD) calculator is a tool to determine your pregnancy’s due date based on the first day of your last menstrual period. As your pregnancy progresses, your doctor can perform ultrasounds that may give a more accurate due date.
How do doctors determine your due date?
If your menstrual cycle was regular before you became pregnant, your doctor will base your estimated due date off the first day of your last period.
If your cycles were not regular prior to becoming pregnant, your doctor may use an ultrasound to gauge how far along you are in your pregnancy.
How likely am I to give birth on my due date?
Approximately 60 out of 100 pregnant people give birth on or before their estimated due date[1]Pregnancy and birth: When your baby’s due date has passed. National Library of Medicine. Accessed 08/10/2022. .
Can you plan a pregnancy due date?
You can try to plan what month your baby may arrive when trying to conceive, but since term pregnancies vary in length from 37 to 42 weeks, it’s unlikely you’ll be able to plan the exact due date.
Programmer scheduling development
In the first part of this article, I want to touch on general information about the estimates of the timing of the work, consider how the estimate is involved in project activities and what significance it has in the final implementation.
Why do we need project time estimates
There are no objective forecasts for the completion of an IT project by a certain date. If the forecast is made, something will still suffer: either deadlines, or functionality that will be cut, or a programmer working overtime due to obligations to complete the task on time. Since forecasts are not honest, why make them then? It so happened that for the successful existence of the product, the people managing it must understand when this or that feature will be available to users. This knowledge simply cannot exist without evaluations of the performance of work on the implementation of this feature. Job evaluations are almost more important than the job itself. The cost of implementation directly depends on the assessment. Often at the evaluation stage it becomes clear that the game is not worth the candle, the chances of success are low, and the costs are too high. But if the project is nevertheless implemented, then more complex mathematics comes into play.
Entering the market first is more important than the number of features at the start. Often, after evaluating the original plan, it becomes clear that it is better to modify it, simplify it, or make a phased entry into the market.
Performance evaluation directly affects the product development strategy and plays a critical role in the company's success in the early stages of a startup's life.
In healthy adult companies, the estimates of the terms of work are given by the performers themselves, based on the requirements provided to them. They can be assisted by senior colleagues if the former do not have enough experience for this. There are, of course, other options, but we will not touch on them, because. their variability is too high and is of no practical interest. If a programmer is asked about the date by which a particular task will be completed, then he can give some estimate. But experienced managers multiply this figure by 2 or even 3, and wise managers then add another 30%.
In the second part of the article, we will discuss why this approach works and why programmers do not need to become more pessimistic. The topic of planning is very broad. I am not ready to give an exhaustive description of the entire planning process. I will not build models, draw graphs and diagrams, I will try not to use a lot of scary words. The article will be reduced to an assessment by the performer, my experience, observations and advice received from more experienced colleagues.
How planning is reflected in the project cycle
Voicing feature requirements
Most projects have a release schedule or a scheduled date by which functionality should be available to users. Usually in companies there are people who know in which direction to develop the product. Product managers, CEO, producer - whatever you call it, the role in our context is the same: they have a vision of the market, an understanding of what is most important now.
Based on this, they form business requirements. Everyone has their own approach to discussing and formalizing requirements. The discussion can be a verbal agreement, a presentation, or a text document with pictures (this option is usually preferred). My favorite way to discuss requirements is to talk about them while waving my arms and drawing on the whiteboard with a marker. But even this option is better to fix not only with a photograph of the board, but also with text. It happens that the director of the company approaches the programmer and asks him to code something as quickly as possible and test his hypothesis for some users on the production tomorrow. In this case, there can be no planning, so we will leave it outside of our article.
High-level evaluation of feature implementation
After the idea is formed, the developers must say whether the task is feasible, how long it may take to complete all the requirements or each one separately.
In simple cases, performers immediately understand what to do. The task may be typical for the performer or trivial in implementation. In more difficult cases, performers may give a high-level assessment such as "Well ... the day may be gone", "Even hell is right" or "If it's 'A', then hold my beer, otherwise it's a long time." Such an assessment is based on historical data or analogies that the performer has encountered. Usually no one expects this estimate to be accurate.
Planning the timing and composition of the feature
If the preliminary estimates suit the business, then they begin to work on the feature, look for special cases, write a User Story - they put strength into the feature. Very often at this stage there are changes in requirements, the original plan becomes the tip of the iceberg or is modified beyond recognition. There may appear requirements for security, system stability to loads, a graph of business entity state transitions - yes, anything that was immediately too complicated to describe (or they simply didn’t think about it).
Adjusted estimate
Based on the specified business requirements, programmers evaluate future changes in the code, draw up a task plan without detailing. A person responsible for the feature from the development side is allocated, who solves technical issues, chooses the implementation method, and makes architectural decisions. A way to implement the feature is planned, they check whether the changes will fit into the current architecture, whether refactoring is required and whether it can be done without it. A couple of estimates are usually given - fast implementation (technical debt is growing) and with minimization of software entropy (technical debt is not growing or decreasing). Project managers know better than programmers that if you constantly choose fast implementations, they will soon cease to be “fast”. Their scores will rise above the line chart, and it may end up being easier to rewrite the application than trying to close the technical debt and develop the existing one.
Therefore, the choice of a fast implementation is less preferable and requires strong arguments for its necessity. In the end, you still need to put things in order, and this is longer than not littering right away.
Finalization of requirements
Based on the revised estimates received, project managers, together with product managers, choose a release date and, if it suits everyone, start the process. If not, then they try to more parallelize tasks by dedicating more programmers. If they are not there or parallelization fails, then either part of the requirements is abandoned, or the functionality is divided into two releases. After such a decision, the person responsible for the feature from the development side can make adjustments to the assessment. Sawing functionality is not a free pleasure. While deadlines are usually offset by adopting fast implementations in code, once action is taken by managers, it's okay to go along with them.
The main thing is that it does not become a habit. After the grades are received and everyone is satisfied with everything, the requirements are frozen. If there are changes, they go into the next release, or are resolved privately.
Milestone synchronization
When implementing a project, it happens that one task takes more than planned, while the other takes less. In order not to be paranoid that due to one task, the release time will go, milestones are created - key points at which plans must correspond to reality. The project manager, without interfering in the process, can see from the outside how far the developers are behind the plan, provide support to those who are stuck, and see the impending threat to the deadline for the feature in time.
Retrospective
After the functionality has been tested and released, it would be good to reduce the plans to the fact, highlight the extreme values of inconsistencies, try to analyze the reasons, understand whether they can be systematic or if it is an accident and this will not occur in the next project.
This process should be treated as learning. Management should not go on a witch hunt, and programmers should take questions about the causes of inconsistencies as a career advancement point.
Conclusion
We looked at the need for planning and estimating the timing of projects, ran through a typical project cycle and saw the role that timing plays. On this, we will finish the first part. The second part of the article will talk about how programmers evaluate individual tasks and how the error can be made acceptable for industrial use.
How do you estimate the timing of different tasks?
How to plan your time and turn in work on time
How many times have you managed to complete a job on time without going into emergency mode? Counted by bending the fingers of one hand? It's a shame. Especially since you set the deadlines yourself each time. It turns out that this is not mysticism, but a well-studied thinking trap.
Every time we start a new task or project, we misjudge how long it will take to get the job done. This happens again and again, even if we have already encountered similar problems. As a rule, underestimation of time leads to negative consequences, starting with a violation of the work schedule and ending with a failure to deliver the project. It turns out that what prevents us from looking at things realistically is the belief that having the right experience will allow us to cope with a known task faster than in the past. This belief is called the planning error. We are suffering from it.
What is planning error
Psychologists use this term to describe people's tendency to underestimate the amount of time it will take to complete a task. Studying this phenomenon, psychologists came to the conclusion that the planning error occurs for two main reasons:
- 1) due to refusal to take into account past experience in performing a similar task;
- 2) because of the assumption that there will be no complications that could delay the completion of the task.
But there is good news. By understanding the reasons why a person falls prey to a planning error over and over again, you can learn how to avoid it. There are special techniques to avoid falling into this trap.
Use past data
Ask yourself how long it took you (your team) to complete a similar task last time and what challenges you faced. This can be done, for example, with the help of special applications - time trackers. When evaluating the period for which you undertake to complete the next similar task, take into account the data received.
Ask someone else to make an estimate
Psychologists have noticed that people often make mistakes in estimating the time it takes to complete a task when they make a schedule for themselves, and very rarely when they do it for someone else. Moreover, the availability of data on past experience and their absence have little effect on the accuracy of time estimation. If you're particularly suffering from a scheduling error, ask a friend or colleague to estimate how long you'll take to complete a given task.
Set time intervals
While working, you may encounter something that you did not expect. Therefore, it is always better to set a time interval for the execution of a task. To do this, it is worth using the so-called cone of uncertainty. At the beginning of the work on the project, when you know little, you are most mistaken in terms of execution: this time can be at least four times less than the established one and at most four times more. For example, you initially expect to complete a task in two days, therefore, in fact, it may take as much as half a day, or eight days. As the work progresses, these estimates will change, becoming more accurate.
The Cone of Uncertainty can also be used to combat excessive optimism. Let's say you initially decided that you would complete the task in four days, and using the cone of uncertainty, you received an interval for the delivery of work from one to 16 days. Try to take the upper value of the range as the original value and see how it all ends.
Use a triple estimate
This technique also aims to avoid the effects of over-optimism by developing and considering different scenarios:
- best,
- worst,
- most likely.
Given the trend towards an optimistic estimate, the best-case scenario is likely to be the same as your original estimate; the most likely will take into account past experience when performing similar tasks; the worst will help determine how long it will take to work if things go wrong. After estimating the task completion time for each scenario, derive an average and use it as an actual one.
Calculate the fiction coefficient
Finding out how optimistic you are about your own abilities is easy. Select a number of tasks that you have to solve. Estimate how much time you plan to spend on them, and record this. After completing each task, write down how much time it actually took you to complete them. Compare the initial estimate with the actual term and present the difference as a percentage.
