A due date is not just a curiosity. It determines when each checkup, test and vaccine is due. How it is calculated, what happens in each trimester, and the warning signs that mean seeing a doctor without delay.
The first question after learning about a pregnancy is almost always the same. When is the baby due?
The curiosity is natural. But that date carries far more weight than curiosity.
Pregnancy care is, in practice, a matter of timing. Which test belongs in which week, when the ultrasound is done, when vaccines are given, what needs checking at which stage. All of it depends on knowing exactly how many weeks along you are.
And the foundation of that calculation is the estimated due date, or EDD.
The trouble is that in many families here, the date is treated as an estimate in the loosest sense. "About three months, I think." "Sometime around winter." As a result, the checkups do not happen on time either.
The most widely used method starts from the first day of your last menstrual period.
Add 280 days, or 40 weeks, to that date and you get the estimated due date.
One detail matters here. It is the day the period started, not the day it ended. People get this wrong often, and it shifts the whole calculation by several days.
The other factor is cycle length. The standard calculation assumes 28 days. If your cycle is consistently longer or shorter than that, the date shifts accordingly.
When this method will not work
If periods are irregular, or you do not remember the date of the last one, this calculation can be off. In that case, an ultrasound in the first trimester is the most reliable way to establish dating.
And remember that this is an estimated date. Very few babies arrive on it exactly. A window of about two weeks either side is considered normal.
Checkups happen at the right time. Which checkup falls when is worked out in gestational weeks.
Tests are done in the correct window. Some tests are only meaningful in specific weeks. Done too early or too late, the results are not reliable.
Problems are caught early. Whether the baby is growing as expected is judged against the week count.
Preterm risk becomes visible. Without knowing how many weeks you are, it is hard to tell whether early pain is normal or concerning.
You can prepare. Where the delivery will happen, who will be with you, how the costs will be met, whether your blood group is known. All of it can be sorted in advance.
In 2016 the World Health Organization updated its guidance to recommend at least eight contacts with a health provider during pregnancy: one in the first trimester, two in the second, and five in the third.
The earlier recommendation was four. Research showed that fewer visits increased the risk of stillbirth, which is why the number was raised.
Bangladesh's national guideline still specifies a minimum of four visits, timed as:
First checkup: between 8 and 12 weeks
Second checkup: 24 to 26 weeks
Third checkup: around 32 weeks
Fourth checkup: 36 to 38 weeks
The key point is that four is the minimum, not the target. More is better where possible. And if your doctor identifies a risk and asks you to come more often, that must be followed.
There is another reality here. First checkups tend to happen late. Many women in Bangladesh have their first visit around 20 weeks, when the guideline says it should be within 12. Yet the first trimester is when the baby's major organs form, and it is precisely then that guidance matters most.
First trimester
The baby's major organs form during this period, which makes two things especially important.
First, starting folic acid on your doctor's advice. It helps reduce the risk of neural tube defects.
Second, not taking any medicine without a doctor's advice. Any medication at this stage can affect development. Do not buy anything from a pharmacy on your own, and tell your doctor about any medicine you were already taking.
An ultrasound during this period gives the most reliable dating.
Second trimester
For most women this is the more comfortable stretch. Nausea eases and energy returns.
Movement usually becomes noticeable during this period. Blood pressure, blood sugar and anaemia are monitored.
Iron and calcium supplements typically come in around now, though what and how much is for your doctor to decide.
Third trimester
Checkups become more frequent. The baby's position and growth, and the mother's blood pressure, are monitored regularly.
Tracking the baby's movements matters a great deal at this stage. If movement suddenly reduces or stops, see a doctor without delay.
This is also the time to finalise delivery arrangements. Where you will go, how you will get there, who can drive at night, who can donate blood if needed. Settling this in advance saves time in an emergency.
If any of the following appear during pregnancy, do not wait, whatever the hour.
Vaginal bleeding
Severe headache, particularly with blurred vision or sensitivity to light
Convulsions
Fever
Severe abdominal pain
Sudden swelling of the face, hands or feet
Reduced or absent fetal movement
Waters breaking well before term
Difficulty breathing or extreme weakness
None of these should be left until morning.
The tetanus vaccine (Td) is provided free to pregnant women under the EPI programme. It protects both mother and newborn against neonatal tetanus.
How many doses you need depends on how many you have had before. Ask about this at your first checkup, and bring any previous vaccination card with you.
It is this programme that allowed Bangladesh to eliminate maternal and neonatal tetanus in 2008.
Adding 280 days to the first day of your last period, then figuring out which weeks the checkups fall in, is tedious to do by hand.
There is a free tool on our site for exactly that.
Enter the first day of your last period and your cycle length, and you get:
The estimated due date
Exactly how many weeks and days along you are
Which trimester you are in and what matters at that stage
How many days remain and how far along you are as a percentage
A full checkup schedule showing which are due and which have passed
The likely date of conception
You can save the whole thing as an image or share it with family. No cost, no account needed.
Once you have the checkup dates, put them in your phone calendar with a reminder a few days ahead.
A second schedule begins as soon as the baby arrives: the childhood vaccination schedule.
BCG right after birth, then Pentavalent, PCV and polio at 6, 10 and 14 weeks, followed by measles and rubella at 9 and 15 months. These are also free at government EPI centres.
Those dates can be worked out the same way. Enter the child's date of birth and you get the exact day for every vaccine.
Generate your child's vaccination schedule
Gynecologist and Obstetrician for routine antenatal checkups, tests and delivery.
Medicine Specialist if you already have diabetes, high blood pressure, a thyroid condition or heart disease. Care is then coordinated with your obstetrician.
Pediatrician for newborn care and vaccination after birth.
On DoctorsFindBD you can search by area and specialty, with chamber addresses and visiting hours in one place.
Knowing one date makes everything else easier to arrange. When to see the doctor, when to test, when to prepare. It all rests on that single calculation.
Work out the date, save it to your phone, and put the checkup days in your calendar.
World Health Organization (WHO) WHO recommendations on antenatal care for a positive pregnancy experience: who.int
World Health Organization (WHO) New guidelines on antenatal care recommending a minimum of eight contacts
Directorate General of Health Services (DGHS), Ministry of Health & Family Welfare, Bangladesh National maternal health guideline and Expanded Programme on Immunization: dghs.gov.bd
PLOS One Status of the WHO recommended timing and frequency of antenatal care visits in Northern Bangladesh: journals.plos.org
