First off, don’t stress if you’ve gone past your expected due date, i.e. you’ve been exactly 40 weeks pregnant. While the pregnancy due date is calculated as 40 weeks from your last period’s first day, a normal pregnancy can be as short as 38 weeks and as long as 42 weeks.
Remember, due dates are not set in stone, so it could be that the due date calculation was a bit off or your baby isn’t ready to come out yet.
If your pregnancy goes into 41-42 weeks, it's called a late-term pregnancy. If your pregnancy is 42 weeks or longer, it is considered a postterm or a past-due pregnancy.
In such cases, try to be patient, consult your Doctor, and keep an eye out for labor signs.
Your Doctor may recommend inducing labor or coming in for weekly/biweekly visits and testing to ensure that your baby is healthy and developing properly.
Pregnancy Due Date Calculator
**Disclaimer: This tool is for informational purposes only. It is important to consult to your doctor/gynecologist.
How is My Due Date Calculated?
You can calculate your expected due date based on the following:
1. First day of your last period:
One of the most common ways of predicting a baby’s due date is using your last menstrual period’s (LMP) first day in the calculation.
Since most pregnancies last around 40 weeks (or 38 weeks from conception), the best way to estimate your baby’s due date is to count 40 weeks (or 280 days) from your last period’s first day. You can also subtract 3 months from your last period’s first day and add 7 days to get your expected due date.
Remember, the due date for a pregnancy is an estimate and not set in stone.
2. Conception date:
You can calculate your pregnancy due date based on your conception date. If you’ve been tracking your ovulation symptoms or have been using ovulation test kits, you may know when you’ve conceived. Adding 266 days to your conception date will give you your expected due date.
3. Ultrasound scan:
An early ultrasound can help you know your date of conception more accurately. Ultrasound scans can help calculate your estimated due date especially in case of the following:
- If you have irregular periods
- You’re 35 or older
- You have encountered miscarriages or pregnancy complications before
- Your expected due date can’t be determined based on your physical exam and last menstrual period
Your pregnancy milestones, such as the first time your baby’s heartbeat is heard (usually around Week 9 or 10) and the first time you feel your baby’s fetal movement (usually between Week 18 and Week 22), can help determine your expected due date more accurately.
4. IVF transfer date:
If you’ve got pregnant through IVF, use your IVF transfer date to calculate your estimated due date. Since most embryo transfers happen either 3 days or 5 days after egg retrieval and fertilization, you can determine your expected due date using the following:
- If you had a Day 3 transfer, count 263 days from the transfer date to calculate your expected due date.
- If you had a Day 5 transfer, count 261 days from the transfer date to calculate your expected due date.
Can My Due Date Be Planned?
If you want to time your pregnancy due date to coincide with a season, a holiday, or even summer vacations so that you can spend more time with your newborn, you can try and plan your conception accordingly. However, you may not be able to plan the exact day on which you’d give birth.
To try and plan your baby’s due date, you can use our Ovulation Period Calculator. This online tool uses your last period’s first day and your typical menstrual cycle length to predict your most fertile period. This helps increase your chances of getting pregnant.
Is It Possible To Choose When To Give Birth?
You can go for an elective delivery, i.e., choose the date that you’ll give birth on. If there’s a specific medical reason for an early delivery, it’s best not to wait. However, if you and your baby are healthy, it’s better to wait and let the baby set the due date. Delivering early could result in lasting health problems as the baby is still undergoing a lot of development even in the last 4 weeks of pregnancy.
How Likely Is It For Me To Give Birth On My Expected Due Date?
Whether the expected due date is determined using our Due Date Calculator or by your Doctor, it is an approximate date. According to a study, about 68% of women gave birth 11 days before or after their expected due date (as calculated by ultrasound at 11-14 weeks).* It is as likely for you to go into labor on the expected due date as it is on any other day in the two weeks before or after.
What’s Next If I Already Know My Due Date?
If you already know when your baby is due, check out Parentune’s 40 Weeks of Pregnancy calendar.
Use this week-by-week pregnancy calendar to track your pregnancy progress. You can learn about pregnancy diet tips, your nutrition requirements, your baby’s nutritional needs for all-round growth and development, when your prenatal tests may be due, what prenatal care you may need to take, and when you’ll hit various milestones, e.g., when your baby's heart starts beating.
Is It Possible For My Expected Due Date To Change Later?
If during a first trimester ultrasound scan, your baby is found to be much bigger or smaller than the expected size for that gestational stage, your Doctor may revise your estimated due date. In such a case, your Doctor will measure your baby’s size to determine how far along you are and then give you a new due date.
A change in the expected due date is likely to happen if you have irregular periods. This makes it difficult to pinpoint your conception date.
Parentune is dedicated to feeding you the most useful, insightful, and reliable information on pregnancy and parenting. All our content is reviewed by our expert panel before you see it. We refer to credible sources while creating and updating our content. These include well-established and respected global and Indian health organizations, academic research institutions. professional associations of doctors and other experts, and published studies in peer-reviewed journals.
ACOG. 2019. Fertility awareness-based methods of family planning. American College of Obstetricians and Gynecologists.