Pregnancy in Weeks, Months, and Trimesters
Pregnancy can be a confusing time, especially when it comes to trying to translate weeks into months. This guide will help make sense of it all and keep you informed on what’s happening with your body as you progress through your pregnancy.
Pregnancy is typically broken down into three trimesters, each lasting around three months. Within each trimester, there are roughly 10-12 weeks. Knowing how to translate weeks to months during pregnancy can be helpful in understanding what’s happening with your body as you grow and progress through your pregnancy.
Most women don’t give birth at exactly 40 weeks pregnant, so it’s impossible to know exactly how long it might be until you meet your baby. Your due date is just a guess – but it’s a good one! Knowing about pregnancy trimesters and how to translate weeks to months in pregnancy is really important. Check out our pregnancy weeks and months chart to help break it down for you if you’re still confused by the end.
How Many Weeks Pregnant Am I?
When your healthcare provider determines your due date, they count 40 weeks from the first day of your last menstrual period (LMP) instead of trying to guess the exact date of conception.
Doctors and other healthcare providers use your LMP simply because most women don’t know exactly which day they ovulated. And because sperm can live inside of you for up to a week, knowing the day you had sex doesn’t necessarily mean it’s the day the baby was conceived.
Using the LMP to calculate your due date means that by the date of your missed period and suspected pregnancy, you are already around four weeks pregnant.
You can visit our Pregnancy Due Date Calculator if you want to check exactly how many weeks you are.
How Many Weeks Are in a Pregnancy?
There are 40 weeks in a “standard” pregnancy – though there really isn’t any such thing as a standard pregnancy. Many babies come earlier than 40 weeks, and many come later.
This not only varies between different women, but it can be vastly different in the same woman during separate pregnancies.
But in the most general terms, 40 weeks is a reasonable expectation.
How Many Weeks Are in a Trimester?
Trimester literally means “3 months.” So each trimester lasts around 13 or 14 weeks.
Your first trimester lasts until you are 13 weeks along. This is the time when most women keep their pregnancies a secret, as it is the trimester when most miscarriages occur.
The second trimester spans from week 14 to 27. This is generally the “fun” trimester. It’s the one where most morning sickness is gone, energy goes up and you’re most likely to enjoy your pregnancy.
The third and final trimester is the first day of your 28th week all the way until you give birth. This is the time most women create their birth plans and have their baby showers.
How Many Trimesters Are in a Pregnancy?
There are three trimesters: the first trimester (early pregnancy), the second trimester (mid-pregnancy), and third trimester (late pregnancy).
If you ever get confused, remember that “tri” means three – like a tricycle has three wheels or triple means three of something.
How Many Months Pregnant Am I?
Use our handy chart to figure out how the weeks of pregnancy correspond to months. It can be helpful to visualize it on a screen to fix it in your mind.
Fun fact – your period before your positive test counts as your first month of pregnancy!
Isn’t a Month Four Weeks Long?
Four weeks is 28 days. And while all months have 28 days, only February stops there. The other months all either have 30 or 31 days. This means that the number of weeks and months of pregnancy don’t quite match up. It’s why some months in the chart show four weeks long, and some show five weeks.
Is Pregnancy Nine or Ten Months?
The confusion here is understandable. Again, because a lot of people think a month is four weeks, it stands to reason that 40 weeks would be ten months. However, the truth is that 40 weeks is just a little more than 9 months. Of course, if you go past your due date, then maybe you could come closer to ten months…
When Will I Actually Have My Baby?
If you count 280 days (40 weeks) from the first day of your last menstrual period, you can determine your due date. But always remember that it is only an estimate. Believe it or not, only 5 percent of babies are actually born on their due date. You could as easily deliver any time two weeks before or after your due date. A baby is considered full term any time from 37 weeks, though obviously it’s preferred that the baby be as close to 40 weeks as possible.
Please also note that not everybody ovulates exactly two weeks after their LMP, so the best way of determining how far along you are is to get an early ultrasound. This will show how developed it is and give a good indication of its age.
Not sure how far along you are? Use our handy Pregnancy Calculator to figure out where you are in your pregnancy, when you conceived, when you are due, and more!
Katie Reed is a passionate writer and mother of four vivacious boys from Salt Lake City, Utah. Drawing from her own journey through TTC, pregnancy, and the joys of raising children, she offers a wealth of insight into the world of motherhood. Beyond her heartfelt tales, Katie delights her readers with family-friendly recipes, engaging crafts, and a curated library of printables for both kids and adults. When she’s not penning her experiences, you’ll find her crafting memories with her husband and sons—Dexter, Daniel, Chester, and Wilder.
