Understanding pregnancy trimesters and calculating your weeks
The four trimesters
One of the first questions after a positive pregnancy test is: "How far along am I?" Knowing how pregnancy is divided into trimesters and how to track your weeks helps you prepare for each stage of this amazing journey.
Pregnancy is split into four trimesters, each about three months long. From conception to delivery, the entire process typically lasts around 40 weeks, with both your body and your baby undergoing incredible changes. But the journey doesn’t end at delivery. The weeks after birth, often called the fourth trimester, are a vital time for healing, bonding, and adjusting to life with your newborn.
First Trimester (Weeks 1-12): Your baby’s earliest development happens here. You might experience symptoms like fatigue and morning sickness as your body adjusts.
Second Trimester (Weeks 13-27): Many find this the most comfortable phase, with nausea often easing up. You’ll start feeling baby movements and have regular check-ups to monitor growth.
Third Trimester (Weeks 28-40+): Your baby grows rapidly, and your body prepares for birth. While excitement builds, you may also face new physical challenges as your due date nears.
Fourth Trimester (Birth to 12 Weeks Postpartum)
The weeks after birth are a period of healing, bonding, and major adjustment. Your baby is adapting to life outside the womb, and you’re adjusting to new routines, feeding, and recovery. This stage is just as important as the others and deserves care, rest, and support.
How to calculate your pregnancy weeks
To figure out how many weeks pregnant you are, you first need to remember the first day of your last period (called your last menstrual period, or LMP). This date is used as the starting point for your pregnancy timeline. It might seem a bit strange to start counting from before you got pregnant, but it helps create a consistent way to track pregnancy since everyone's menstrual cycle can be different.
Typically, pregnancy is calculated based on a 28-day menstrual cycle. If your cycle is shorter or longer, it can slightly affect your timeline.
Once you have your LMP, you just count the weeks from that date. Think of it this way: every seven days after your LMP marks a new week. So, if it’s been 21 days since your LMP, you are considered about 3 weeks pregnant.
Tools like online pregnancy calculators or an early ultrasound can help confirm your stage.
Understanding these basics helps you follow your pregnancy’s progress and look forward to what’s next!