How Far Along Am I? Why Pregnancy Dating Matters Before the Abortion Pill
If you just had a positive pregnancy test, one of your first questions may be:
“How far along am I?”
Pregnancy dating can be surprisingly confusing because pregnancy does not begin counting from the day you conceived.
Healthcare providers typically count pregnancy beginning with the first day of your last menstrual period (LMP). A full-term pregnancy is approximately 40 weeks from that date.
That means when someone is called “six weeks pregnant,” conception usually occurred roughly four weeks earlier—not six.
Knowing your approximate gestational age is useful in any pregnancy. It becomes particularly important if you are considering abortion pills.
How do I calculate how many weeks pregnant I am?
Start with the first day of your last menstrual period.
Count the number of weeks from that date until today. That gives you an estimated gestational age.
For example, if the first day of your last period was eight weeks ago, your pregnancy would generally be dated at approximately eight weeks—even though conception likely happened later.
This method assumes a fairly predictable menstrual cycle.
And that is where things can get complicated.
What if I have irregular periods?
Your last menstrual period is an estimate—not a measurement of conception.
Dating based on LMP traditionally assumes a 28-day menstrual cycle with ovulation around day 14. But real bodies do not always follow that calendar.
Ovulation can occur earlier or later. Cycles can be longer or shorter. Stress, illness, hormonal changes, breastfeeding, coming off birth control, PCOS, and other circumstances can affect menstrual patterns.
ACOG also notes that people do not always remember their exact LMP accurately. When the LMP is uncertain, ultrasound dating can provide additional information.
So if you’re thinking, “I know I’m pregnant, but I honestly don’t know how far along I am,” you are not unusual.
Is an ultrasound more accurate than my last period?
In early pregnancy, ultrasound can be particularly useful for confirming pregnancy dating.
ACOG states that first-trimester ultrasound—through 13 weeks and 6 days—is the most accurate ultrasound method for establishing or confirming gestational age. Crown-rump-length measurements in this period generally estimate gestational age within approximately 5–7 days.
That does not mean every pregnancy requires an ultrasound.
It means an ultrasound can answer questions that counting calendar dates alone sometimes cannot.
Why does pregnancy dating matter before taking abortion pills?
The FDA-approved regimen of mifepristone followed by misoprostol is indicated for terminating an intrauterine pregnancy through 70 days, or 10 weeks, from the first day of the last menstrual period.
So if you are considering abortion pills and you aren’t certain when your last period occurred, knowing how far along the pregnancy is may matter.
It is also important to understand that pregnancy dating is only one question.
Another is:
Where is the pregnancy located?
Why does pregnancy location matter?
The FDA-approved abortion pill regimen is for an intrauterine pregnancy—a pregnancy developing inside the uterus.
An ectopic pregnancy occurs outside of the uterus and cannot be treated with abortion pills.
Ectopic pregnancy is uncommon, and most women considering medication abortion will not have one. Still, it is important not to ignore symptoms or risk factors.
ACOG recommends further evaluation when there is a history or symptoms that may suggest ectopic pregnancy, including certain risk factors such as previous ectopic pregnancy or tubal surgery, or symptoms such as one-sided pain or vaginal bleeding.
Severe abdominal or pelvic pain accompanied by bleeding, significant lightheadedness, or fainting can signal an emergency and requires immediate medical care.
Do I have to have an ultrasound before taking abortion pills?
Not necessarily.
For someone with regular menstrual cycles who is certain about the date of her last period and has no symptoms or risk factors for ectopic pregnancy, current professional medical guidance does not require an ultrasound before medication abortion.
But you are allowed to want more information than the minimum required.
You might want an ultrasound because:
- your period dates are uncertain;
- your cycles are irregular;
- your pregnancy test surprised you;
- you aren’t sure whether you are 6 weeks or 10 weeks pregnant;
- you’ve had pain or bleeding;
- you want to know more about your pregnancy before deciding; or
- you simply aren’t ready to make an irreversible decision based only on information gathered online.
That is a reasonable reason to slow down.
What if I’ve already ordered abortion pills?
Ordering abortion pills and taking abortion pills are two different decisions.
If medication has already arrived—or is on the way—you can still take time to learn more about your pregnancy and think through your options.
If you obtained mifepristone online, it is also worth knowing where it came from.
Under current FDA regulations, certified prescribers can prescribe mifepristone and certified pharmacies can send it through the mail. However, the FDA specifically recommends against buying mifepristone outside of its regulated REMS system because medications from unregulated or foreign sources may not have FDA-verified safety, effectiveness, or quality.
Sometimes “How far along am I?” isn’t the biggest question
You may have started searching because you wanted a number.
Six weeks? Eight weeks? Ten weeks?
But there may be another question underneath it:
“What am I going to do?”
That question cannot be calculated with a pregnancy app.
Maybe you are afraid your relationship will end.
Maybe you are worried you won’t finish school.
Maybe another child feels financially impossible.
Maybe your parents don’t know.
Maybe the father of your baby wants one decision and you want another.
Maybe you’re scrolling late at night because telling another human being you’re pregnant suddenly makes everything feel more real.
We understand why searching online feels easier.
Sometimes it is.
But easier isn’t always what you need most.
Before you make the decision alone, come talk with someone
You don’t have to arrive at The Bridge with a decision already made.
In fact, before you know what you’re going to do is one of the best times to come.
The Bridge Wellness South provides free and confidential pregnancy testing, limited obstetrical ultrasound when appropriate, and one-on-one support for women facing unexpected pregnancies.
We can help you gather information about your pregnancy and talk through the circumstances surrounding it.
We don’t perform or refer for abortion. The Bridge is life-affirming because we believe there is value in both lives involved in an unexpected pregnancy.
But being life-affirming also means caring about what you are facing.
Bring the questions.
Bring the uncertainty.
You don’t have to have everything figured out before you walk through our door.
The Bridge Wellness South
100 Eagles Walk
Stockbridge, GA 30281
770-957-8288
Pregnancy testing, limited ultrasound, and our other services are offered at no cost. Contact us today.
Frequently Asked Questions
When does pregnancy start counting?
Pregnancy is conventionally dated beginning with the first day of the last menstrual period, rather than the day conception occurred.
If I’m six weeks pregnant, did I conceive six weeks ago?
Usually not. Because gestational age starts with the last menstrual period, conception typically occurs about two weeks later in a typical 28-day cycle, although ovulation timing varies.
How accurate is an early ultrasound for pregnancy dating?
First-trimester ultrasound is the most accurate ultrasound method for establishing or confirming gestational age. Crown-rump-length dating through 13 weeks and 6 days has an accuracy of approximately plus or minus 5–7 days.
How late can you take the abortion pill?
The FDA-approved mifepristone regimen with misoprostol is indicated through 70 days, or 10 weeks, calculated from the first day of the last menstrual period.
What if I don’t know when my last period was?
An ultrasound may help establish gestational age when menstrual dates are unknown or uncertain.
Can I make an appointment even if I haven’t decided what I’m going to do?
Yes. You don’t have to make a pregnancy decision before coming to The Bridge. Gathering information and talking through what you’re facing can be part of making that decision.
This article provides general educational information and is not a substitute for individualized medical care. If you are experiencing severe abdominal or pelvic pain, fainting, significant dizziness, heavy bleeding, or another medical emergency, seek emergency medical attention.