Your gestational period is in fact 40 weeks long, but it starts counting on the first day of your last period. You aren’t actually pregnant during weeks 1 and 2, and by the time you see a positive result on a pregnancy test, you are already considered four weeks pregnant. The first month has already passed! You can count your gestational period in weeks or months. Your healthcare provider will use weeks, but you might start using months in conversation when you get further along. Your friends and coworkers might find “I’m 8 months” easier to understand than “I’m 32 weeks.” In this article, we explain how to figure out how many weeks or months along you are throughout your pregnancy.
Pregnancy Weeks vs. Months
Planning for a nine-month pregnancy can be confusing if you look at the total number of weeks in the average pregnancy. When you break down the numbers, it would seem that pregnancy lasts 10 months, not nine. There are about 40 weeks in a full-term pregnancy. If you assume that a month is exactly four weeks long, that makes 10 months of pregnancy. The problem with this calculation is that it assumes that each month lasts 28 days. But most of our calendar months last 30 or 31 days. To confuse matters even more, there is also the issue of when you actually became pregnant. While an exact date may not matter to everyone, you can estimate the date based on testing. By the time you have a positive pregnancy test, you are usually about four weeks pregnant. The truth is that a full-term pregnancy lasts between nine and 10 months. To establish clarity about your stage of pregnancy and estimated due date, your practitioner will track your pregnancy in weeks rather than months.
Pregnancy Trimesters
While you might explain your pregnancy in weeks or months, many expectant moms also describe their pregnancy in trimesters. Each trimester lasts about 12 to 13 weeks. There are three trimesters in a full-term pregnancy.
First Trimester
This early trimester usually includes weeks 1 to 13, or months 1 to 3. This is considered a short trimester because many women don’t know that they are expecting during the early weeks of pregnancy.
Second Trimester
The middle trimester usually includes weeks 14 to 27, or months 4 to 6. Many moms consider this to be the easiest and most comfortable trimester.
Third Trimester
Your last trimester may include weeks 28 to 40, or months 7 to 9. But many women go into labor before week 40 and some may stay pregnant a week or two longer.
Counting Pregnancy Weeks
Your practitioner will count your pregnancy in weeks to help them more accurately assess the health of you and your baby. If you are unclear about your pregnancy week, be sure to ask for your provider’s guidance. Babies born before 37 weeks gestation are considered pre-term and will need specialized care. About 8% of babies will be born pre-term. If you go past 42 weeks gestation, your healthcare provider will likely induce your labor to avoid complications related to late-term delivery.
Once you get your estimated weeks of pregnancy, you can use that information and your due date to plot your pregnancy by week at home. To do this, note the day of the week that your baby is due. Then choose that day of the week in your current week of pregnancy and start counting forward. For example, if your due date is on a Monday and you are currently in your fourth week of pregnancy, note that date on your calendar with “week 4.” Then note that on the following Monday you’ll be five weeks along. The Monday after that you would be six weeks along. Every Monday moving forward you gain a week of pregnancy, until around 40 weeks.
Counting Pregnancy Months
Understanding your pregnancy in weeks, months, and trimesters can be confusing enough. But you’ll also be faced with plenty of pregnancy questions from others. When someone asks: how far along are you? It is usually easiest to reply in months. But the answer can vary. There are different ways to lay out the months of pregnancy depending on whether you emphasize the first trimester or the last trimester. Here are some common breakdowns of the months of pregnancy.
Pregnancy by Month: Emphasis on First Trimester
This monthly breakdown assumes that early pregnancy is very important. Since many women aren’t aware that they are pregnant during the first two weeks, month one is extended to six weeks.
Month 1: Week 1 through week 6 Month 2: Week 7 through week 11 Month 3: Week 12 through week 16 Month 4: Week 17 through week 20 Month 5: Week 21 through week 24 Month 6: Week 25 through week 28 Month 7: Week 29 through week 32 Month 8: Week 33 through week 36 Month 9: Week 37+
Pregnancy by Month: Emphasis on Third Trimester
This weekly pregnancy breakdown includes every moment from the last normal menstrual cycle and considers the fact that some women have their babies earlier than forty weeks.
Month 1: Week 1 through week 4 Month 2: Week 5 through week 8 Month 3: Week 9 through week 12 Month 4: Week 13 through week 16 Month 5: Week 17 through week 20 Month 6: Week 21 through week 24 Month 7: Week 25 through week 28 Month 8: Week 29 through week 32 Month 9: Week 33+
Pregnancy by Month: Emphasis on Length of a Month
This breakdown takes the date of your last menstrual period and counts until the same date of the subsequent months. For example: If the date of your last menstrual period was April 17:
Month 1: April 17 through May 16Month 2: May 17 through June 16Month 3: June 17 through July 16Month 4: July 17 through August 16Month 5: August 17 through September 16Month 6: September 17 through October 16Month 7: October 17 through November 16Month 8: November 17 through December 16Month 9: December 17+
As you can see from the three schedules, there are different ways to describe which month of pregnancy you are in based on how you interpret the weeks. There is no right or wrong way to answer when people want to know how far along you are. Simply provide the week or month you feel is appropriate for your gestational age.
A Word From Verywell
Remember that when people inquire about your pregnancy progress, there is no need to explain the difference between weeks and months. Whether you answer five months or six months on the chart above, you are still 24 weeks pregnant. Simply choose the answer that best suits you. Sometimes you might feel very pregnant and six months makes you feel better than five months. Or, perhaps you are not anxious for the pregnancy to be over and you would prefer to be five months pregnant. This mental game is one that can help you stay sane through a potentially discombobulating time.
