If I get pregnant this month, when am I due? A month-by-month due date chart

Short answer

If you get pregnant in a given month, when are you due? Count about 266 days, or 38 weeks, forward from conception, which lands roughly nine months later. Clinicians count the same pregnancy from the first day of your last period instead: by convention, the American College of Obstetricians and Gynecologists (ACOG) says, "the EDD is 280 days after the first day of the LMP" — the estimated due date is 40 weeks after your last menstrual period (1). Both counts land on the same day, because the 280-day rule assumes ovulation on day 14 of a 28-day cycle (1).

A due date is an estimate, not an appointment. In a study of 18,708 spontaneous births, only 5% happened on the estimated date, and about 66% within a week of it (4). If your baby does not arrive on the date in a chart, or conceiving in a planned month takes longer than you hoped, missing the date is not in itself a sign that something has gone wrong, and it is not your fault.

Note: this article explains what research and clinical guidelines say and is not medical advice. Every date here is approximate and does not replace the due date your clinician sets, usually with a first-trimester ultrasound. If you are pregnant or recently gave birth, bleeding, a severe headache, vision changes, chest pain, trouble breathing or your baby moving less need care right away, not a chart.

When am I due if I get pregnant this month? Month-by-month due date chart

Find the month you conceived, or plan to, on the left. The middle column is the due date if conception happened that month (conception + 266 days). The right column answers a question people often mean instead — "my last period started in this month" — using ACOG's 280-day count (1). From the May row down, due dates fall in the next calendar year; the April row (and the March row in the right-hand column) straddles New Year.

Approximate. If February 29 falls inside the pregnancy, dates shift by one day. Your clinician's due date replaces any chart (1).

"Get pregnant in" here means the month of conception, which is ovulation day, not necessarily the day you had sex: in a landmark study of 221 women, conception occurred only with intercourse during the six days ending on the day of ovulation (6). If you only know when your last period started, use the right-hand column.

If I get pregnant in August, when am I due?

If you conceive in August, you are due between about April 24 and May 24 of the next year (an August 15 conception gives about May 8). If your last period started in August, the 280-day count gives May 8 to June 7 (1).

If I get pregnant in July, when am I due?

If you conceive in July, you are due between about March 24 and April 23 of the next year (a July 15 conception gives about April 7). If your last period started in July, the due date falls between April 7 and May 7 (1).

If I get pregnant in June, when am I due?

If you conceive in June, your due date falls between about February 22 and March 23 of the next year (a June 15 conception gives about March 8). If your last period started in June, expect March 8 to April 6 (1).

If I get pregnant in October, when am I due?

If you conceive in October, you are due between about June 24 and July 24 of the next year (an October 15 conception gives about July 8). If your last period started in October, the 280-day rule gives July 8 to August 7 (1).

If I get pregnant in November, when am I due?

If you conceive in November, your due date falls between about July 25 and August 23 of the next year (a November 15 conception gives about August 8). If your last period started in November, expect August 8 to September 6 (1).

Want a baby in a certain month? When to conceive: the reverse chart

To have a baby in a given month, conception needs to happen about 266 days before a due date in that month: roughly the same calendar month nine months earlier, about a week later in the month. The chart runs the arithmetic backward — due date minus 266 days for conception, minus 280 days for the start of the last period (1). For due dates from January through August, both windows fall in the year before.

Approximate. Conception means ovulation day.

A due date in your chosen month does not guarantee a birth in it. The term categories used by ACOG and the Society for Maternal-Fetal Medicine (SMFM) run from early term at 37 weeks, three weeks before the due date, through late term at the end of 41 weeks, almost two weeks after it (2). If the month matters, a mid-month due date leaves the most room either side.

When to conceive to have a baby in October

For an October due date, conception would happen between about January 8 and February 7 of the same year, with the last period starting between about December 25 and January 24. A mid-October due date (October 15) corresponds to conception around January 22.

When to conceive to have a baby in April

For an April due date, conceive between about July 9 and August 7 of the year before; the last period would start between about June 25 and July 24. An April 15 due date corresponds to conception around July 23.

When to conceive to have a baby in May

For a May due date, conceive between about August 8 and September 7 of the year before, with the last period starting between about July 25 and August 24. A May 15 due date corresponds to conception around August 22.

When to conceive to have a baby in June

For a June due date, conception would fall between about September 8 and October 7 of the year before, with the last period starting between about August 25 and September 23. A June 15 due date corresponds to conception around September 22.

How to calculate due date: the 280-day and 266-day rules

To calculate a due date by hand, add 280 days (40 weeks) to the first day of your last period, or 266 days (38 weeks) to the date of conception. For a 28-day cycle they give the same answer; the 14-day gap is the time from period to ovulation that the convention assumes (1).

When is my due date based on conception?

Your due date based on conception is the conception date plus 266 days. If you know your ovulation day, this count is more direct. In a study that pinned down ovulation with daily urine hormone tests, the median time from ovulation to birth was 268 days, or 38 weeks and 2 days (3) — within two days of the convention.

If I got pregnant today, what would my due date be?

Add 266 days to today's date: conceiving on October 8 gives a due date of about July 1 the next year. If your last period started today, add 280 days instead (October 8 → about July 15).

What if my cycles aren't 28 days?

Most aren't exactly. In 612,613 ovulatory cycles logged in a fertility app (Natural Cycles; most of the authors work for the company), the mean cycle was 29.3 days and the time from period to ovulation averaged 16.9 days, with a 95% range of 10 to 30 days (5). With long cycles you probably ovulated after day 14, so an LMP-based date comes out early; an early dating ultrasound settles that (1). For how the cycle works, see our guide to the menstrual cycle phases.

Reverse due date calculator: when did I conceive by due date?

To work out when you conceived from your due date, subtract 266 days; to find when your last period would have started, subtract 280. A due date of July 1 points to conception around October 8 of the year before and a last period starting around September 24.

Conception date calculator: how close can you get?

Within about a week, not to the day. ACOG describes first-trimester ultrasound dating, based on the embryo's crown-rump length, as accurate to within ±5–7 days (1). Ovulation day varies from cycle to cycle (5). And conception can follow sex several days earlier (6). So a due-date calculation cannot pin conception to one particular time you had sex when two were close together; paternity is established by testing, not arithmetic.

How accurate is a due date?

A due date is the best single estimate available, and most babies are still not born on it. ACOG's Committee Opinion 700 says the date should be set as soon as the last period, the first accurate ultrasound, or both are known, then discussed with the patient and documented (1).

• By convention, the due date is 280 days after the first day of the last period — The starting point for most calculators and charts

• First-trimester ultrasound dating is accurate to ±5–7 days — The most accurate way to set the date

• Before 9 0/7 weeks, a discrepancy of more than 5 days is a reason to change the date — Your date may move after an early scan

• Before 14 0/7 weeks, a difference of more than 7 days means the date follows the ultrasound — A bigger mismatch means the scan wins

• Later changes are reserved for rare circumstances — Once set, the date usually stays

• Without an ultrasound confirming the date before 22 0/7 weeks, a pregnancy is considered suboptimally dated — Ask about dating if you have not had a scan

Gestational age sets the timing of prenatal care and tests (1), so use the date in your medical record.

What percent of babies are born on their due date?

About 5%. In an Australian study of 18,708 women who went into labor spontaneously, "only 5% of births occurred on the eDOB" — the estimated date of birth — whether the date came from the last period or from an ultrasound at any of the stages studied (4). About 66% came within seven days.

How often are babies born on their due date when conception is known exactly?

Still rarely. In the Early Pregnancy Study, which identified ovulation by daily urine hormones in 125 natural conceptions, pregnancy lengths spanned 37 days even after excluding six preterm births (3). The authors add that "an individual woman's deliveries tend to occur at similar gestational ages" — useful if you have given birth before.

What counts as full term?

Full term is 39 weeks 0 days through 40 weeks 6 days, which on the calendar is the week before your due date through six days after it. ACOG and SMFM replaced the single label "term" with four categories because "neonatal outcomes, especially respiratory morbidity, vary depending on the timing of delivery" within the five weeks once called term (2).

• Early term — Weeks of pregnancy: 37 0/7 through 38 6/7; Relative to your due date: 21 to 8 days before

• Full term — Weeks of pregnancy: 39 0/7 through 40 6/7; Relative to your due date: 7 days before to 6 days after

• Late term — Weeks of pregnancy: 41 0/7 through 41 6/7; Relative to your due date: 7 to 13 days after

• Postterm — Weeks of pregnancy: 42 0/7 and beyond; Relative to your due date: 14 days or more after

The right-hand column is arithmetic from the 40-week due date. It is why "due May 15" is better read as "probably born between late April and late May." Birth before 37 weeks is preterm. If you are pregnant and notice vaginal bleeding or fluid leaking, or your baby's movements stop or slow, the CDC lists these among urgent maternal warning signs that need medical care immediately (13) — do not wait to see whether it fits your chart.

Can you plan the month you conceive?

You can choose when to start trying, but not the month it works. In a German prospective study of couples timing sex to the fertile window, the cumulative chance of conception was 38% after one cycle, 68% after three, 81% after six and 92% after twelve (8). The American Society for Reproductive Medicine states that "approximately 80% of couples will conceive in the first 6 months of attempting pregnancy" (7).

So read the reverse chart with those odds in mind: if the January 8 – February 7 window for an October baby does not work, the next cycle points to November. A realistic plan is a range of acceptable birth months, trying from the start of it. Our article on how long it takes to get pregnant covers the odds by age and when guidelines say to see a doctor, and our preconception guides for women (90 days) and men (75 days) cover the months before trying.

Your body changes before, during and after pregnancy — and so do your numbers

Expect resting heart rate, heart rate variability (HRV) and sleep to change in pregnancy. Studies describe these shifts in typical pregnancies, so expect your numbers to differ from your usual ones. A changed number is something to note and discuss with your clinician, not something to read as good or bad on your own.

Heart rate rises. A meta-analysis of 39 studies of healthy pregnancies found mean heart rate rose from 79.3 beats per minute at 10 weeks to 86.9 at 40 weeks, a change of 7.6 beats per minute — "lower than previously thought," the authors note (9). These are clinic averages, not a range for any app reading.

HRV falls, then partly recovers. A Finnish study analyzed night-time smartwatch data from 58 women through pregnancy and three months after birth: heart rate rose in the second trimester and fell in the third, while HRV fell in the second and rose again in the third. The authors concluded that heart rate increased and HRV decreased as pregnancy progressed, and that both went back after delivery (10). It was a small group wearing one device model.

Sleep changes by trimester. Across 24 studies with 11,002 participants, 45.7% of pregnant women reported poor sleep quality, and it worsened from the second to the third trimester. The authors write that "some reduction in sleep quality is expected during pregnancy, but complaints of very poor sleep quality could require intervention" (11).

After birth, routines break. Among 20 first-time mothers wearing a wristband, daily wear fell from 17.9 hours in the second trimester to 14.4 hours after birth, and eight wore it only occasionally or not at all, partly from fear of scratching their babies (12). Gaps in a postpartum record are common.

That is the case for a personal record before, during and after pregnancy: "my sleep has been much worse for two weeks," with dates, makes a prenatal visit more concrete. It is a diary of what changed for you, not a verdict on the pregnancy.

And in the same breath: a gradual rise in resting heart rate is described in studies; a fast-beating heart with chest pain, trouble breathing, dizziness or fainting is not a trend to watch. The CDC lists chest pain or a fast-beating heart, trouble breathing, dizziness or fainting, and overwhelming tiredness among urgent maternal warning signs in pregnancy and the year after delivery, and says to "seek medical care immediately" (13). Chest pain or severe trouble breathing is a 911 call.

Planning a pregnancy by month: the questions people ask next

I know my due date: when did I get pregnant?

If you are due in a given month, you most likely conceived about 266 days, or 38 weeks, before your due date — roughly nine months earlier, about a week later in that month. A due date in July points to conception between about October 8 and November 7 of the year before; a due date in December points to March 10 – April 9. Because first-trimester ultrasound dating is accurate to ±5–7 days (1) and sex up to five days before ovulation can lead to pregnancy (6), treat the result as a window of a week or two.

Why am I "two weeks pregnant" at conception?

Because pregnancy is counted from the first day of your last period, not from conception. The 280-day convention assumes a 28-day cycle with ovulation on day 14 (1), so when an egg is fertilized the official count already reads about two weeks. That is why a "40-week" pregnancy lasts about 38 weeks from conception.

Why did my due date change after my ultrasound?

Because an early ultrasound is usually more accurate than the date of your last period. ACOG puts first-trimester ultrasound dating at ±5–7 days, and says that before 9 0/7 weeks a discrepancy of more than 5 days is a reason to change the due date, and before 14 0/7 weeks a difference of more than 7 days means the date should follow the ultrasound (1). ACOG also reports that only about half of women accurately recall their last period.

Are first babies more likely to be late?

Not according to the study that measured pregnancy length most precisely. In the Early Pregnancy Study, with ovulation identified by daily hormone tests, the authors saw no association between pregnancy length and parity (whether it was a first baby), body mass index, alcohol intake or the baby's sex (3). The sample was small, which limits what it can rule out. What they did find: women with longer pregnancies tended to have longer pregnancies in their other births too.

How is a due date set after IVF?

From the embryo's age, not from a period. ACOG states that for pregnancies conceived with assisted reproductive technology, the gestational age derived from the procedure should be used to assign the due date (1). That makes the starting date precise, but not the birth day: pregnancy length still varies between people even when conception is known exactly (3). Your clinic will give you the date to use.

When to seek care, and how to bring this up with your doctor

Seek care now, not at your next visit, for urgent maternal warning signs. The CDC's list for pregnancy and the year after delivery: a headache that won't go away or gets worse; dizziness or fainting; changes in vision; fever of 100.4°F or higher; extreme swelling of the hands or face; thoughts of harming yourself or your baby; trouble breathing; chest pain or a fast-beating heart; severe nausea and vomiting; severe belly pain that doesn't go away; the baby's movement stopping or slowing; vaginal bleeding or fluid leaking during pregnancy; vaginal bleeding or discharge after pregnancy; severe swelling, redness or pain of a leg or arm; and overwhelming tiredness (13). The ACOG Foundation's version advises contacting your provider right away and, if you cannot reach them, going to the nearest emergency room; for thoughts of hurting yourself or your baby, options include calling 911 (14). You can also call or text 988, the Suicide & Crisis Lifeline. Chest pain, severe trouble breathing or fainting is a 911 call.

Before trying, say it in one sentence: "We're planning to start trying in the next few months — is there anything I should do first?"

At your first prenatal visit, bring what dating depends on: the first day of your last period and how sure you are of it, your usual cycle length, any ovulation test results, and, after IVF, your transfer date and embryo age.

Questions worth asking:

• "Is my due date based on my last period, the ultrasound, or both — and did the scan change it?"

• "Which weeks count as early, full and late term for me?" (2)

• "Which signs mean I should call you, and which mean I should go to the hospital?"

Bring a one-page record, not a pile of screenshots: sleep changes, tiredness, stress, anything that made you uneasy, with dates.

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How Welltory helps — and what it cannot do

The limits first. Welltory is a general wellness product, not a medical device. It does not diagnose, detect, predict, monitor, prevent, treat or mitigate any condition, including pregnancy complications. It does not calculate a due date, track your cycle or pregnancy, or tell you how a pregnancy is going. Welltory states that phone-camera measurements may not be accurate during pregnancy, because the body works differently then. Nothing below will help you conceive in a chosen month, reach term, or change how a pregnancy goes.

What it can be is a dated diary before, during and after pregnancy. With a supported wearable, resting heart rate, HRV, sleep analysis, stress minutes and Battery are recorded the same way each day and shown against your own history, not a population range or a line marked normal. Expect them to change in pregnancy (9, 10).

You note it; the app records it. When a stress stretch appears on your Today screen and the app asks "What happened?", you can tap a suggested tag, type a few words, or just talk: "started trying", "positive test", "nausea", "short night", "back pain", "baby up at 3am". You can add a note any time with the plus icon; it goes into your Journal. The app does not know any of this; you are the one putting it on the record.

After two to three weeks of tagging, My Patterns has something to work with. My Patterns collects the tags you add to stress and rest stretches on the Today screen, so it needs iOS with an Apple Watch or Oura. Patterns start to show at around seven tagged events, and the picture gets clearer the more you tag. It shows which tagged situations tend to come alongside stressful stretches, which tags do not happen often but hit your body hard, trends by day of week, heart-rate data, and every time a tag occurred.

Bring it to your prenatal appointments. The Journal (Premium) keeps your measurements, tags and notes, and from the Welltory web app you can export a CSV (Dashboard → choose a chart → Export) to show your doctor or midwife. It is a record you made, not a conclusion the app reached; any pattern in it is an association to discuss, not a cause and not a warning system. Expect gaps after birth (12).

The red flags belong here too, in the same type size: the CDC's urgent warning signs include bleeding or fluid leaking, a severe or worsening headache, vision changes, chest pain or a racing heart, trouble breathing, fainting, extreme swelling of the hands or face, your baby moving less, or thoughts of harming yourself or your baby; they need medical care immediately (13, 14). Chest pain, severe trouble breathing or fainting is a 911 call; for thoughts of harming yourself or your baby, call 911 or call or text 988. Those are not tags.

Where to find other people in the same situation. If you are also living with an energy-limiting condition while planning a pregnancy, Welltory runs a paid, moderated community called Energy Lab for women aged 18 to 65 living with ME/CFS, long COVID, fibromyalgia, POTS, MCAS and similar. It runs alongside the app: you keep collecting your own data, and the Lab is where people learn to read it together, with a medical board answering the science. It is education and peer support, not medical care, it does not replace your clinician, and there is a 14-day money-back guarantee on a first purchase.

How we made it

Made with AI tools, then edited and fact-checked by the Welltory team. See our Editorial & AI policy.

Data analysis by Jane Smorodnikova, co-founder of Welltory and the person who built the methodology behind how we read physiological data.

Written by Tatsiana Yashyna.

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