How Pregnant Am I? A Complete Guide to Calculating Gestational Age

You got a positive test. Now comes one of the most practically important questions you’ll ask: how far along am I, exactly?

It sounds like a simple number. But it is far more consequential than most people realize. Your gestational age determines which pregnancy options are medically available to you, how urgent your timeline is, when prenatal care should begin, and in 2025, whether certain legal windows are already closing depending on your state.

Getting this number right — and getting it early — is one of the most important first steps you can take, regardless of which direction you’re considering.

This guide explains everything: how gestational age is calculated, why it often confuses people, what every stage of pregnancy means for your options, and where to get an accurate answer you can actually trust.

👉 Not sure what to do next once you know how far along you are? Start with our full guide: Unplanned Pregnancy: Understanding All Your Options

What Is Gestational Age — and Why Does It Start Before Conception?

Gestational age is the clinical measurement of how far along a pregnancy is. Here is the part that surprises almost everyone: it is not counted from the day you had sex or the day you conceived. It is counted from the first day of your last menstrual period (LMP).

Gestational age is measured in weeks by calculating the time difference between the first day of the woman’s last menstrual cycle and the current date. According to this method, a baby that has just been conceived — approximately two weeks after the last period — is already two weeks old in gestational age. Friends in Adoption This means that on the day sperm actually met egg, you were already clinically considered about 2 weeks pregnant. And by the time a home pregnancy test turns positive — usually around 4 weeks — you are already nearly a month into your gestational age count.

Why does this matter so much?

Because every abortion restriction, every medical guideline, every gestational limit in state law is measured in gestational age — not from conception, not from when you found out. When a state law bans abortion at “6 weeks,” that means 6 weeks from your last period — which is often only 2–4 weeks after actual conception, and frequently before many people even know they are pregnant.

Understanding this isn’t just academic. It is a practical tool for protecting your access to your options.

3 Ways to Calculate How Far Along You Are

Method 1: Count From Your Last Menstrual Period (LMP) — Most Common

Take the date the first day of your last period started and count forward in weeks to today.

Step-by-step example:

• Last period started: January 6
• Today’s date: February 20
• Weeks elapsed: approximately 6 weeks and 2 days pregnant

Gestational age calculator tools estimate how many weeks pregnant a person is by using the first day of the last menstrual period. This method defines gestational age as the number of weeks and days counted from that date. National Abortion Federation This method is reliable if your cycles are regular — typically around 28 days. If your cycles are longer, shorter, or irregular, your LMP calculation may be off, sometimes significantly.

Method 2: Use a Pregnancy Due Date Calculator

Online due date calculators are free, anonymous, and medically sound for regular cycles. Enter your LMP and you’ll instantly get an estimated gestational age and due date. Many reputable reproductive health organizations offer these calculators directly on their sites.

Using the LMP method, the estimated due date (EDD) is calculated by adding 280 days (40 weeks) to the first day of the last menstrual period. This assumes accurate recall, regular 28-day cycles, and ovulation on day 14. EDD by LMP can be off by more than two weeks in some cases. American Adoptions If your cycle doesn’t match the standard 28-day assumption, don’t rely on this number alone — use it as a starting point, then confirm with an ultrasound.

Method 3: Ultrasound — The Gold Standard

An ultrasound is the most accurate method available for determining gestational age, especially if you have irregular periods, don’t remember your LMP, or want to verify your calculation.

In general, an ultrasound helps accurately estimate gestational age up to 95%. It can also determine the baby’s gender, check the development of the uterus, monitor the baby’s growth and health, and predict the expected due date. This method is particularly useful for women who don’t remember the date of their last period. Taylor & Francis Online

What an ultrasound can tell you:

• Confirms the pregnancy is inside the uterus — ruling out a dangerous ectopic pregnancy
• Detects cardiac activity (from approximately 6 weeks gestational age)
• Measures the embryo or fetus to estimate gestational age within a few days’ accuracy
• Identifies any early complications that require immediate attention

Ultrasounds are typically available from 6–8 weeks of pregnancy. Before 6 weeks, the embryo may be too small to clearly visualize, even with a transvaginal ultrasound.

Two types of ultrasound used in early pregnancy:

• Transvaginal ultrasound — A small wand is inserted vaginally, used primarily in very early pregnancy (before 8–10 weeks) for better image clarity
• Transabdominal ultrasound — Uses a probe on the abdomen, more commonly used after 10–12 weeks

Both are safe, non-invasive, and painless for the vast majority of people.

What If My Cycle Is Irregular?

Irregular periods make LMP calculation unreliable — sometimes by several weeks. Conditions that commonly cause irregular cycles include:

• Polycystic Ovary Syndrome (PCOS) — One of the most common causes of cycle irregularity
• Recent hormonal birth control use — Cycles can take weeks or months to normalize after stopping the pill, patch, or ring
• Breastfeeding — Suppresses ovulation and can make cycles unpredictable
• High stress or significant weight changes — Both can delay or skip ovulation
• Thyroid disorders — Both hypothyroidism and hyperthyroidism affect cycle regularity
• Perimenopause — Cycles become irregular in the years approaching menopause

If any of these apply to you: Do not rely on your LMP. Go directly for an ultrasound at a licensed medical clinic. It is the only way to get an accurate gestational age if your cycle is irregular.

The Full Gestational Age Timeline — What Every Stage Means for Your Options

This is the table competitors don’t give you — the complete picture of what each gestational stage means across every option available to you:

Weeks Pregnant (From LMP)	What’s Developing	Abortion Access	Adoption & Parenting Notes
1–4 weeks	Fertilization through implantation; hCG hormone rises	All options open; too early for ultrasound in most cases	Home test may just be turning positive
4–6 weeks	Embryo implanting; gestational sac visible by ultrasound; cardiac flicker may appear	Medication abortion available; all options open	Many people find out they’re pregnant in this window
6–10 weeks	Embryo forming; heartbeat detectable; major organ systems developing	Medication abortion (FDA-approved through 10 weeks / 70 days); aspiration also available	First prenatal appointment ideally scheduled in this window
10–13 weeks	End of first trimester; embryo becomes a fetus; external genitalia forming	Medication abortion window closing at 10 weeks; aspiration abortion available	First trimester screening (nuchal translucency ultrasound) typically occurs
13–16 weeks	Second trimester begins; fetal movement starts; facial features developing	Aspiration abortion available to approximately 14–16 weeks	Adoption planning can begin at any point; no gestational cutoff
16–24 weeks	Significant fetal development; viability threshold approaches at 22–24 weeks	D&E procedure; availability varies significantly by state	Most states with restrictions become more limiting in this window
24+ weeks	Viability threshold; survival outside womb possible with intensive care	Abortion only available for serious medical indications in most states	Prenatal care and birth planning in full focus

Understanding the Trimester System

Pregnancy is divided into three trimesters, each covering a distinct developmental and clinical phase:

First Trimester: Weeks 1–13 This is the most critical developmental period for the embryo. Major organ systems — brain, heart, limbs — form during these weeks. It is also the period when miscarriage risk is highest (approximately 10–20% of known pregnancies). Most abortion options, including medication abortion, fall within this window.

Second Trimester: Weeks 14–27 Often described as the most physically comfortable trimester. Nausea typically subsides, and energy returns. Fetal movement becomes detectable (called “quickening”) between approximately 16–25 weeks. In-clinic abortion procedures (D&E) are available throughout this trimester in states that permit them.

Third Trimester: Weeks 28–40+ The final stretch before birth. The fetus gains weight rapidly and prepares for life outside the uterus. Abortion in this trimester is extremely rare and occurs almost exclusively for serious medical reasons.

Pregnancy is often described as lasting about 40 weeks from the first day of the last menstrual period. Delivery timing is classified according to the American College of Obstetricians and Gynecologists as: preterm before 37 weeks, early term 37–38 weeks, full term 39–40 weeks, late term 41 weeks, and postterm 42 weeks and beyond. National Abortion Federation

Why the “6-Week Ban” Is Earlier Than It Sounds — A Critical Explainer

This is one of the most widely misunderstood facts in reproductive health in 2025 — and it has real consequences for people’s access to care.

A “6-week abortion ban” sounds as though it gives people six weeks after finding out they’re pregnant to make a decision. It does not. Here’s the math:

• Gestational age is counted from your last period — not from when you learned you were pregnant
• Most people don’t take a pregnancy test until they’ve missed a period — which typically happens at approximately 4 weeks gestational age
• Add a few days to get a test, process the result, and book a clinic appointment
• Factor in any mandatory waiting periods (24–72 hours in many states)
• Factor in clinic availability, travel time, and cost
• You may already be at or past 6 weeks before you’ve made a single phone call

This is not an abstract concern. It is the practical lived reality for many people in states with 6-week restrictions. Understanding your gestational age as early as possible — ideally as soon as a pregnancy test is positive — is the most effective way to preserve your access to the full range of options.

What Is an Ectopic Pregnancy — and Why Is It a Medical Emergency?

An ectopic pregnancy occurs when a fertilized egg implants outside the uterus — most commonly in a fallopian tube, but occasionally in the ovary, cervix, or abdominal cavity. It cannot result in a live birth. And if left untreated, it can rupture the fallopian tube and cause life-threatening internal bleeding.

Warning signs of an ectopic pregnancy:

• Sharp, stabbing pain in the lower abdomen — often on one side
• Pain in the shoulder (caused by internal bleeding irritating the diaphragm)
• Vaginal bleeding that differs from a normal period — often lighter and more irregular
• Dizziness, lightheadedness, or fainting
• Nausea and weakness

⚠️ If you experience sharp one-sided pelvic pain alongside a positive pregnancy test, seek emergency medical care immediately. This is a time-sensitive emergency. An ultrasound will confirm whether the pregnancy is in the uterus. Ectopic pregnancies require medical treatment — either medication (methotrexate) or surgery — and cannot be managed with watchful waiting.

This is another reason why early ultrasound confirmation matters — not just for gestational age, but for your immediate safety.

How Gestational Age Affects Each of Your Three Options

If You’re Considering Abortion

Gestational age is the single most important factor determining which type of abortion is available to you, who can provide it, and what it will cost. Here is the precise breakdown:

• Medication abortion (abortion pill): FDA-approved through 10 weeks (70 days) LMP. Most telehealth providers follow this limit. Available via in-person clinics, telehealth, and mail-order pharmacy depending on your state.
• Aspiration / vacuum aspiration abortion: Available from early pregnancy through approximately 14–16 weeks, depending on provider and state law. Fast, effective, done in a clinic setting.
• D&E (dilation and evacuation): Used from approximately 13 weeks onward. Availability decreases significantly after 20–24 weeks depending on state law.

The practical rule: the earlier you confirm your gestational age, the more options remain available. Every week matters — not because decisions should be rushed, but because medical and legal windows are real.

If You’re Considering Parenting

Prenatal care should ideally begin by 8–10 weeks gestational age — or as soon as you decide to continue the pregnancy. Early prenatal care is directly associated with better health outcomes for both parent and baby. Key first steps include:

• Starting a prenatal vitamin with folic acid immediately — even before your first OB appointment
• Scheduling an appointment with an OB/GYN or midwife
• Enrolling in Medicaid for pregnancy coverage if you don’t have insurance (applications can be submitted at any point during pregnancy)
• Connecting with WIC (Women, Infants, and Children) for nutritional support — eligibility begins during pregnancy

If You’re Considering Adoption

Adoption planning has no gestational age cutoff. It can begin at any point during pregnancy — even in the third trimester, or in some cases, after birth within state-specific legal timeframes.

That said, most adoption specialists recommend beginning conversations earlier rather than later. Earlier planning means more time to research agencies, understand your legal rights in your specific state, and create an adoption plan that genuinely reflects your wishes — including what kind of contact, if any, you want with your child after placement.

Where to Get an Accurate, Trustworthy Ultrasound

Best options:

• Planned Parenthood — Offers low-cost ultrasounds at most locations nationwide. Provides accurate gestational age and full, unbiased options counseling.
• Federally Qualified Health Centers (FQHCs) — Community health centers that offer sliding-scale or free services regardless of income. Find one at findahealthcenter.hrsa.gov
• Your OB/GYN or primary care provider — If you have a trusted provider, a phone call is the simplest first step.
• Telehealth abortion providers — For medication abortion specifically, many licensed telehealth providers can confirm eligibility based on LMP and symptom history without requiring an in-person ultrasound.

Avoid: Crisis Pregnancy Centers (CPCs)

CPCs frequently advertise “free ultrasounds” and appear in top search results for pregnancy-related queries. They are not neutral medical facilities. They are not licensed to provide comprehensive healthcare. And they are explicitly designed to steer you away from abortion — regardless of your circumstances, your health, or your wishes.

Some CPCs have been documented withholding ultrasound results, providing inaccurate gestational age information, and deliberately delaying appointments until abortion access is reduced. Always verify that a clinic is a licensed medical provider before booking an appointment.

Early Signs of Pregnancy — What to Watch For

If you’re not yet sure whether you’re pregnant, here are the most common early symptoms that typically appear between 4–8 weeks gestational age:

• Missed period — The most common and reliable early indicator
• Breast tenderness or swelling — Often one of the first physical signs, caused by rising progesterone
• Nausea (morning sickness) — Can occur at any time of day; typically begins around 6 weeks
• Fatigue — Disproportionate tiredness caused by rapidly rising hCG levels
• Frequent urination — The kidneys process more fluid as blood volume increases
• Light spotting (implantation bleeding) — Occurs when the embryo implants in the uterine wall; easily mistaken for a light period
• Food aversions or heightened sense of smell — Common in early pregnancy due to hormonal shifts
• Bloating or mild cramping — Similar to pre-menstrual symptoms; caused by uterine changes

Everyone experiences different symptoms of pregnancy and at different times. It’s important not to compare your pregnancy to someone else’s because pregnancy symptoms can vary so dramatically.

A National Abortion Federationpositive home pregnancy test is still the most reliable way to confirm pregnancy — and home tests are now accurate enough to detect hCG as early as 10 days after conception.

Frequently Asked Questions

1. Can a home pregnancy test tell me how many weeks pregnant I am?
   Standard home tests confirm pregnancy but do not measure gestational age. Some digital tests estimate “1–2 weeks” or “2–3 weeks” based on hCG concentration levels, but these ranges refer to weeks since conception — not gestational age from LMP — and are rough approximations only. An ultrasound is the only accurate method.
2. What if I don’t remember when my last period was?
   This is more common than people think, and it is completely manageable. An ultrasound can estimate gestational age by measuring the size of the embryo or fetus — even without any LMP information. Tell the clinic you’re unsure of your LMP date; they’re experienced in working with this situation.
3. I have PCOS and my cycles are very irregular. How do I figure out how far along I am? Skip the LMP calculation entirely and go directly for an ultrasound at a licensed medical clinic. PCOS causes irregular ovulation timing, making LMP-based estimates unreliable by potentially several weeks. An ultrasound gives you a measurement-based answer that doesn’t depend on cycle regularity.
4. I’m only 4 weeks pregnant. How much time do I actually have to decide what to do?
   At 4 weeks, you have approximately 6 more weeks before the medication abortion window closes at 10 weeks — longer for in-clinic options, depending on your state. That said, the earlier you have accurate information, the more options remain available. There is no need to rush a decision, but there is value in gathering information promptly. If you need support, call the All-Options Talkline at 1-888-493-0092 — free, confidential, and judgment-free.
5. Does gestational age affect whether I can use a telehealth abortion provider?
   Yes. Most telehealth medication abortion providers require you to be 10 weeks or fewer by gestational age (from LMP). Some providers use symptom-based eligibility screening; others require documentation of your LMP or an ultrasound report. Check with your specific provider for their requirements. If you’re close to the 10-week threshold, prioritize getting your gestational age confirmed as quickly as possible.