How Far Along Am I?

Our how far along am I calculator uses your due date to calculate how many weeks, months and days you are pregnant.
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About How Far Along Am I?

It can be hard keeping up to date with the weeks and months of pregnancy but by using our how far along am I calculator you can quickly check without the guesswork.

Each calculation will give you specific information about the:
  • Week you are in
  • Month you are in
  • Trimester you are in
  • The day a new week begins for you

How far along am I, a question asked frequently by pregnant mothers, refers to the amount of time that has elapsed since the start of the last menstrual period (LMP) and generally not to the amount of time since baby was conceived. Pregnancy is normally counted from LMP which is about two weeks before baby is actually conceived.

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How Far Along Am I Formula

How Far Along Am I Formula:
LMP + Time Passed = How Far Along I Am (Gestational)
LMP = Last Menstrual Period

Why Pregnancy is Counted from the Last Menstrual Period (LMP)

The start of a period is easily observable and usually known to a woman whereas the date of conception is much less likely to be known. Historically, the first day of the last menstrual period (LMP) became the date from which pregnancy is counted even though conception occurs about two weeks later.

The LMP formula is good for working out an initial age of pregnancy but ultrasound is more accurate. Age of pregnancy may be revised following your ultrasound scan.

No LMP Date?

If you don't have a valid LMP date for any reason, your doctor will provide one for you, most likely based on ultrasound measurements.

Definitions


how-far-along-defintions

EDD is an abbreviation for estimated due date.

LMP is an abbreviation for last menstrual period, which is the first day of your last period.

Gestational age is the age of pregnancy when counted from LMP or two weeks before conception.

Fetal age is the age of pregnancy when counted from Conception.

How Long is Pregnancy?

Pregnancy -  from start to due date - is either 40 or 38 weeks' long, depending on the start date used.

Counting from LMP: Pregnancy is 40 weeks from the first day of the last menstrual period (LMP) to the estimated due date. This method of measuring pregnancy adds an extra two weeks since counting starts approximately two weeks before baby is conceived.

Counting from conception: Pregnancy is 38 weeks from conception to estimated due date.

Actual length of pregnancy: The actual length of pregnancy varies greatly among women. Just 4% of babies are born on their due date while 70% are born within 10 days of the estimated due date. The remaining 30% are born more than 10 days before the due date or more than 10 days after the due date.[2]

How Many Weeks Am I?

To calculate how many weeks pregnant you are, start by counting the recurring first day of your last menstrual period until the present time (do not count the day of your LMP). The number of recurring days you count is the number of weeks you are now.

Example:
If your last menstrual period started on a Wednesday, count one week to the next Wednesday. Now keep counting Wednesdays until you reach the present date.

LMP = December 2, 2015
Current Date = February 4, 2016

Calculation:
1st Wed = December 9, 2015 = 1 Week
2nd Wed = December 16, 2015 = 2 Weeks
9th Wed = February 3, 2016 = 9 Weeks
You are 9 Weeks and 1 Day pregnant

Another method to calculate how many weeks pregnant you are, is to count the days from the first day of your Last Menstrual Period (LMP) until you reach todays date. Once you have counted all the days that have passed since your LMP divide the counted days by 7.

The answer will be how many weeks you are now.

How Many Weeks Am I Formula:
(LMP + Days Passed Since LMP) / 7
LMP = Last Menstrual Period

Each of these methods will give you the gestational age of your pregnancy.

How Many Months Am I?

To calculate how many months' pregnant you are, start from the first day of your last menstrual period, then count forward one month and repeat until you reach todays date.

Example:
LMP = December 2, 2015
Current date = February 4, 2016

Calculation:
1 month = January 2, 2016
2 months = February 2, 2016
Months counted = 2. You are 2 Months and 2 Days pregnant.

If your LMP date falls on a day after the 28th and the numerical day of your LMP is not in the month you are counting, then you must count to the last day of that month.
Example:
LMP = January 30, 2015

Calculation:
1 month = February 28, 2016
2 months = March 30, 2016
3 months = April 30, 2016
And so on..

Note: Our months are calendar months but in the pregnancy world a month may be any of the following:

  • 4 weeks
  • 5 weeks
  • A lunar month

Any reference to how many months pregnant you are contains this uncertainty unless the type of month is specified.

How Far Along Am I Based on Ultrasound

Ultrasound in the first trimester is the most accurate method of dating pregnancy.[1] During the scan, baby is measured and the age of pregnancy is estimated by comparing baby's size against recorded averages. If there is a significant difference between gestational age according to LMP and gestational age according to the ultrasound, you may be given a new gestational age and due date based on the ultrasound measurements.[1]

Your pregnancy may also be dated by ultrasound measurement if an LMP formula was not appropriate for your pregnancy for any reason. LMP formulas are not suitable in a number of situations including the following: LMP is not known or is not certain, birth control pills were taken in the two months before LMP, the menstrual cycle is irregular, you are carrying multiples (twins or more).

Although age of pregnancy based on ultrasound measurements is more accurate than age of pregnancy based on LMP, both are estimates and not definitive statements.

How Far Along Am I Using hCG Testing

Age of pregnancy can also be estimated by measuring the levels of hCG (Human Chorionic Gonadotropin) in the mother's blood. The results of this test indicate how far the pregnancy has progressed. Home pregnancy tests are available which can be used in the early stages of pregnancy to measure pregnancy progress.

Other Methods of Pregnancy Dating

Other, less important methods (used by health professionals) for assessing age of pregnancy include measurement of fundal height (size of mother's belly), age of baby's first heart- beat, and time when mom first feels baby's movement.

Understanding Gestational Age

Gestational Age is the length of pregnancy when counted from LMP (last menstrual period). Forty weeks of pregnancy means 40 weeks or 280 days, from the first day of LMP to the estimated due date. The first 2 weeks, when you are not actually pregnant is included for convenience only. Gestational age is 2 weeks ahead of the fetal age.

Forty weeks of pregnancy means 40 weeks or 280 days, from the first day of LMP to the estimated due date. The first 2 weeks, when you are not actually pregnant is included for convenience only.

Example:
When you are 26 Weeks' pregnant, you have completed 26 weeks since the start of your last period but only 24 weeks since baby was conceived (approximately).

Weeks and Days: At times, gestational age may be expressed more precisely to show the number of completed weeks and days since LMP.

Example:
When you are 26 Weeks, 6 Days' pregnant, you have completed 26 Weeks and 6 Days since LMP.

Gestational age begins at LMP:

LMPConception EDD
0 Weeks2 Weeks from LMP40 Weeks from LMP

LMP is used as the start point in measuring pregnancy because the date of conception is usually not known. Even if conception is known, or the pregnancy has been measured by ultrasound, gestational weeks are normally still used to track pregnancy progress as this maintains consistency in record keeping and communication. If LMP is not an appropriate start date, it is replaced with a date two weeks prior to conception or presumed conception.

Gestational ageing can be confusing but it serves a useful purpose by providing a standardized language for obstetricians, midwives, and parents to be. Prenatal appointments and tests are usually based on gestational weeks.

Understanding Fetal Age

Fetal Age: Length of pregnancy from conception. When pregnancy is measured this way, it is 38 weeks, or 266 days from conception to the estimated due date.

Fetal age begins at conception:

Conception EDD
0 Weeks38 Weeks from LMP

Fetal age is closer to the true age of pregnancy since it is counted from conception but is still an approximation if the conception date is assumed and not known for sure. Fetal age is assumed to be 2 weeks less than gestational age.

Researchers, especially embryologists, commonly use fetal age rather than gestational age when referring to pregnancy progress.

Embryonic and Fetal Periods

Pregnancy is sometimes divided into two stages, the embryonic and fetal periods - or three stages, the germinal, embryonic, and fetal periods.

Germinal Period Embryonic Period Fetal Period
Covers the period from fertilization until the blastocyst is fully implanted in the uterus. Begins when the blastocyst is fully implanted in the uterus. Begins at the start of 10 Weeks (gestational) when the major organs are formed.

Notes About the Calculator

Our calculator strives for the highest accuracy, but your pregnancy progress may differ from the calculator's results for a number of reasons including possible miscalculation; errors in input data; individual variations in timing of ovulation and/or conception.

The information provided regarding pregnancy progress and fetal development is a guide through the weeks. It is not specific information for a specific individual but serves as a general guide only. In addition, each pregnancy differs, so any dates, weights and lengths should be considered general information for interest only.

Our guides through the weeks use both standard and metric units of measure including pounds and kilograms.

References

  1. Committee Opinion No. 611. Method for estimating due date. Obstet Gynec. 124 (2014): 863-6. doi: 10.1097/01.AOG.0000454932.15177.be
  2. A. Jukic et al. Length of human pregnancy and contributors to its natural variation. Human Reproduction 28 (2013): 2848 2855. doi: 10.1093/humrep/det297

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Disclaimer: All information featured on weeksduringpregnancy.com should be used for educational purposes only and is not intended to replace medical advice.
Consult your doctor, physician or midwife regarding any personal pregnancy issues or medical conditions.