How to Calculate Due Date Using a Maternity Wheel
Expecting a baby is an exciting journey, you are about to enter into an era which is cute, full of love and a lot of responsibility. One of the first things parents want to know after knowing that they are expecting is the due date. There are multiple ways to know the estimated date but the most commonly used is Maternity wheel also known as pregnancy wheel.
What is a Pregnancy Wheel?
Pregnancy wheel often termed as gestation calculator or a maternity wheel is a tool which professionals use to find a estimated due delivery date. It works by aligning the first day of your last menstrual period (LMP) with the corresponding date on the wheel, which then provides an estimated due date based on a typical 40-week pregnancy.
This tool is very much used in prenatal care because it is accurate in predicting the expected delivery date. But it’s not always true, in the end these are estimates and delivery can occur a little earlier or later as well.
How to Use the Maternity Wheel?
Using a gestation calculator is straightforward and doesn’t require medical expertise. Here’s a step-by-step guide:
1. Find the First Day of Your Last Menstrual Period (LMP)
The LMP is the first day of your last period before conception. This is the most commonly used starting point in pregnancy dating.
2. Align the LMP with the Marker on the Wheel
Turn the pregnancy wheel so that the LMP date aligns with the designated marker (usually indicated as “LMP” or “Start”).
3. Locate Your Estimated Due Date (EDD)
Once the LMP is set, look at the 40-week mark to find your estimated due date. This will show the approximate day your baby is expected to arrive.
4. Track Key Pregnancy Milestones
Most pregnancy wheels also indicate key milestones, such as:
• End of the first trimester (12 weeks)
• Viability milestone (24 weeks)
• Full-term range (37–40 weeks)
This helps parents and healthcare providers monitor progress and plan prenatal care accordingly.
Other Ways to Calculate the Due Date
While a maternity wheel is one of the most traditional methods, there are several other ways to estimate your due date.
1. Naegele’s Rule (Standard Calculation Method)
Naegele’s Rule is a simple formula to determine the due date:
1. Take the first day of your LMP.
2. Add 7 days to this date.
3. Count back 3 months or add 9 months.
For example, if your LMP was January 1st, your due date would be October 8th.
2. Ultrasound Scan
An ultrasound scan is one of the most reliable ways to determine gestational age, especially for women with irregular cycles or those who don’t remember their LMP.
During an ultrasound:
• The doctor measures the size of the fetus.
• Based on these measurements, a due date is estimated.
• Early ultrasounds (between 6–12 weeks) are the most accurate.
3. Online Due Date Calculators
Several online maternity calculators allow you to enter your LMP, ovulation date, or IVF transfer details to estimate your due date. Some popular tools include:
• Prokerala’s pregnancy calculator (source)
• Lifetime Adoption due date tool (source)
While these tools provide quick estimates, they should always be verified with a healthcare provider.
How Accurate is a Pregnancy Wheel?
A pregnancy wheel provides a highly accurate estimate when used correctly, especially for those with regular menstrual cycles. However, individual factors such as ovulation date, cycle length variations, and early fetal growth can influence the actual birth date. Studies show that only 5% of babies are born exactly on their due date, while most arrive within two weeks before or after.
IVF Calculation: How to Determine the Due Date for IVF Pregnancies?
For those who conceived through in vitro fertilization (IVF), the due date calculation differs slightly from the standard pregnancy wheel method. Since the exact date of conception is known in IVF pregnancies, due dates are calculated based on the embryo transfer date.
Here’s how to estimate the due date using IVF calculation:
• For a 3-day embryo transfer: Add 266 days from the egg retrieval or fertilization date.
• For a 5-day embryo transfer: Add 261 days from the embryo transfer date.
Many maternity wheels include IVF-specific calculations, making them helpful for fertility treatments. However, some parents may prefer using online gestation calculators specifically designed for IVF pregnancies.
While a maternity calculator is a useful tool, healthcare providers often supplement it with ultrasound scans for a more precise estimate.
Regardless of the method used, the estimated due date helps expectant parents prepare for the arrival of their baby. However, every pregnancy is unique, and delivery may not always align exactly with the predicted date.
Final Thoughts
A maternity wheel is an easy and effective tool for estimating your due date, but it’s essential to remember that it’s just an approximation. Whether you use a pregnancy wheel, IVF calculation, or an online gestation calculator, tracking your due date helps in planning for a healthy pregnancy.
For the most accurate results, always consult with a healthcare provider who can assess fetal growth through ultrasound and other prenatal care methods.
