ou may have to start counting your pregnancy by days as – 39 weeks one day, 39 weeks two days, and so on (6).
What If Your LMP is Not Known Or Periods Are Irregular?
The due date calculation works ideally if your periods are regular, i.e., follow a 28-day cycle.
If your periods are irregular or you do not remember your last period, you should wait for your first ultrasound pregnancy scan. Also known as dating scan, it will provide the number of weeks remaining for your due date (7).
If the scan does not give the correct results, your doctor may ask you to wait for some more time. Ideally, the dating scan will be done between ten and 13 weeks plus six days (8).
What Are The Three Trimesters In Pregnancy?
The pregnancy period is divided into three, three-month segments, known as trimesters. The division helps understand the changes in the body.
First trimester: It lasts from week one to week 13, when you experience nausea and tiredness.
Second trimester: It lasts from week 14 to week 28. You will feel much better in this period and your pregnancy bump will be seen. Early pregnancy symptoms such as morning sickness, headache, dizziness, fatigue, etc., slowly disappear.
Third trimester: It lasts from week 29 until you birth the baby. You will require extra energy to help your baby grow and beat the tiredness (9).
Does Pregnancy Really Last For Nine Months?
It is based on calculation. 40 weeks adds up to nine calendar months (with 30 or 31 days each) or ten lunar months (with 28 days each) (10).
For instance, if your last period was on January 1, your estimated due date would be October 7 or 8. It equals to nine months and one week (and can be longer if you go beyond the due date).
[ Read: When Is The Best Time To Get Pregnant ]
How Do You Calculate Pregnancy Weeks After IVF (In Vitro Fertilization)?
Calculating weeks of pregnancy and the due date is more precise during an IVF than natural conception. This is because the exact date of embryo transfer or ovulation is known. The insemination or egg retrieval method is scheduled before ovulation in IVF, thus making it more accurate.
The IVF due date is calculated by adding 38 weeks (i.e., 266 days) to the day the eggs were inseminated.
An alternative calculation is by adding 38 weeks to the date of transfer, and subtract the age of embryos from this date. For instance, if it is a three-day embryo transfer, subtract three days and if it is a four-day embryo transfer, subtract four days (11).
It, therefore, gives reliable estimated due dates. Also, with progressing pregnancy, the estimated due date could be more accurate based on ultrasound scans.
[Read: Chemical Pregnancy And IVF ]
Week-to-Month Pregnancy Chart:
If these calculations are making you go nuts, there is a simple breakdown on how the pregnancy weeks, months, and trimesters line up with each other.
If You Are In Your Fifth Week Of Pregnancy, Why Are You Referred To As Four Weeks Pregnant?
Sarah Owen, author of “The Complete Guide To Pregnancy And Child Care”, helps clear the confusion about pregnancy weeks by relating them to a baby’s age. When a baby is one year old, she completes the first 12 months of her life. Though she enters the second year, she is called one-year-old. Similarly, when you complete the first week of pregnancy, you are known to be one-week pregnant even though you enter the second week.
A quick look to understand the terms and counting of pregnancy weeks:
- In your first week of pregnancy, you will be referred to as being zero weeks pregnant
- In your second week of pregnancy, you will be referred to as being one week pregnant.
- In your third week of pregnancy, you will be referred to as being two weeks pregnant.
- And so on.
It is for this reason that when you miss your first period, you are four weeks pregnant though you are in your fifth week of pregnancy (i.e., starting of a new month).
How Accurate Is Your Pregnancy Due Date Calculation?
Due dates are just estimates, which differ from one pregnancy to another. According to a British study, only 4% are known to be born on their due date, and 