The calendar is part of the female profile and needs your separate consent to process health data. There are four ways in:
Pregnancy calendar
Pregnancy app with a week-by-week calendar and due date
Astras is a club. Your personal AI wellness assistant. Its pregnancy calendar, in the Astras app for iPhone, Android and the web, counts completed weeks of pregnancy, your trimester and your estimated due date from the first day of your last period — and shows, week by week, what is usually developing in the baby and changing in your body.
How to start the pregnancy calendar
At sign-up
Turn on “Pregnancy” and set the “Approximate start date” on two ribbons, month and day — the first day of your last period. Under the ribbons you see completed weeks, such as “20 weeks,” and “due around…”. Not sure? Tap “I don’t know the date” and add it later on Home.
In your profile
Open your profile from Settings and switch on “Pregnancy.”
From the cycle calendar
If your plan includes it, mark a day as “Conception”: Astras turns on pregnancy mode and sets the start 14 days before that day.
By telling Karina AI
If your plan includes it and health-data processing is on, say you’re pregnant, and Karina AI asks when conception happened — a date, “three weeks ago,” “I’m 20 weeks,” or “not sure.” With health-data processing off, it doesn’t save a pregnancy or ask for the date.
On Home, the form asks for the first day of your last period in MM/DD/YYYY. It won’t take a date in the future or one more than 42 weeks back.
How Astras counts your weeks and due date
- Estimated due date = first day of your last period + 280 days (40 weeks), the standard calendar rule.
- Weeks = completed weeks since that day: full days ÷ 7, rounded down, from 0 to 42. This is how ACOG writes gestational age: at 20 weeks and 3 days the card says “20 weeks,” and the first seven days show “0 weeks.”
- Trimester (ACOG) = first through 13 weeks 6 days, second from 14 weeks 0 days through 27 weeks 6 days, third from 28 weeks 0 days.
- From a conception date — start = conception − 14 days, so marking conception on March 16 sets the start to March 2.
Example: how far along am I?
Your last period started March 2, 2026. The estimated due date is December 7, 2026. On July 23, 2026 — 143 days later, which is 20 weeks and 3 days — the card shows “20 weeks · trimester 2” and “Due Dec 7, 2026 · in 137 days.”
At the bottom of the card, one line stays in place: “Dates are estimated from the calendar — check with your doctor.” Your clinician may date the pregnancy differently, for example by ultrasound; you can change the start date any time with “Change the date.”
Pregnancy tracker, week by week: what you see
- Top row — completed weeks and the trimester (“20 weeks · trimester 2”), the due date with how many days are left, and “Conception marked” with the date, if you marked it.
- “Baby” — the baby’s approximate size and what is developing that week. For example, at 12 weeks: “Reflexes appear: fingers open and close.”
- “You” — what usually happens in your body. At 20 weeks: “The halfway point of pregnancy.”
- A picture of the baby from 4 to 40 weeks; at 41 and 42 weeks the 40-week picture stays.
- A trimester scale in three segments — 14, 14 and 12 weeks, up to the due date — with a marker for where you are, “Change the date,” and from 28 weeks 0 days an “I gave birth” button.
From 4 to 42 weeks, each week has its own “Baby” and “You” texts, in all 8 interface languages. From 0 to 3 weeks, “Baby” is hidden and “You” shows a short note about the trimester. The texts are neutral, based on ACOG, WHO and NHS guidance, and give no advice or diagnoses.
Baby size by week — a number, not a fruit
Size is a number in your units. From 5 to 19 weeks it’s length; from 20 weeks, weight from the WHO fetal growth chart (the 50th percentile). In US units, 12 weeks is “About 2.1 in.”, 20 weeks “About 11.6 oz.” and 32 weeks “About 4.2 lb.” At 4 weeks no size is shown.
How pregnancy mode changes the rest of Astras
- Cycle calendar — ovulation, fertile days, period forecasts and cycle cards are hidden; the pregnancy calendar takes their place at the top of Home. See the period tracker.
- Water — your calculated daily goal grows by 300 mL; in US units it’s rounded to whole 8-oz glasses, so a 72 fl oz goal becomes 80. See the water tracker.
- Calories — a “lose weight” goal is read as maintenance, the daily target rises by 340 kcal from 14 weeks (second trimester) and by 450 from 28 weeks (third), the reference values ACOG uses, and a hand-set target below maintenance is raised to it. See the calorie calculator.
- Lab results — when a report prints a separate range for pregnancy or a trimester, the report reader picks that printed row using your trimester on the collection date. If the report has no such row, no range is invented. See lab results.
- Karina AI — with health-data consent, the chat knows your completed weeks and days, trimester and due date (details in the FAQ).
When the baby is born
From 22 weeks 0 days the “⋯” menu has “I gave birth,” and from 28 weeks 0 days it’s also a button on the card. Astras first asks “Has your baby been born?” — “Yes, I gave birth” or “Not yet.” Then you pick the birth date and tap “Done”; “Pressed by mistake? Go back” changes nothing. The same menu has “Turn off pregnancy mode,” with “Turn off” or “Keep.”
Either way, the calendar switches back to cycle tracking. After a birth, bleeding in the first four weeks isn’t counted as a period, and predictions return once you mark your first new one.
Privacy
Pregnancy dates are health data: the start date you entered and, later, the end date and whether it was a birth. They’re kept in your Astras account on our server with your cycle log, so they sync between devices. No ads in the app, and we don’t sell your data for money. Nothing about pregnancy is sent to advertising or analytics platforms; ad analytics runs only after you allow it, in every country (California law counts it as “sharing” and a “sale”). Turning off health-data processing with deletion erases these dates along with the cycle calendar.
Frequently asked questions
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Astras adds 280 days to the first day of your last period — the standard calendar rule of 40 weeks. If your last period started March 2, 2026, the estimated due date is December 7, 2026. If you start from a conception date instead — the Conception mark in the cycle calendar or a date you tell Karina AI — Astras sets the start 14 days earlier and counts from there. The due date stays an estimate: the card says “Dates are estimated from the calendar — check with your doctor.” Change the start date at any time and every number on the card updates.
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Your doctor may date the pregnancy by ultrasound or adjust for a cycle that’s longer or shorter than average, while Astras uses only the calendar rule from the date you entered. When the two differ, follow your clinician. Astras doesn’t import dates from medical records or scans; it counts only from the start date in the card. You can edit that date with “Change the date” at any time, and the weeks, trimester and due date update at once.
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Completed weeks — the way ACOG and US clinicians write gestational age. Astras counts full weeks since the first day of your last period, so at 20 weeks and 3 days the card shows “20 weeks · trimester 2,” and the first seven days show “0 weeks.” Trimesters follow the same count: the second starts at 14 weeks 0 days, the third at 28 weeks 0 days. The “Baby” and “You” notes, the size, the calorie add-on and the “I gave birth” button are all set to this count. Karina AI gets the same completed weeks and days the card counts.
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Yes, from 5 weeks on. Size is a number in your own units, not a comparison with a fruit: length through 19 weeks, then weight from the WHO fetal growth chart at the 50th percentile. In US units, it’s about 2.1 inches at 12 weeks, about 11.6 ounces at 20 weeks and about 4.2 pounds at 32 weeks. These are typical reference values, not a measurement of your baby, and they don’t tell you whether your baby is growing as expected — only an ultrasound and your clinician can. A picture of the baby for that week sits next to the text.
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You can still turn on pregnancy mode. At sign-up, tap “I don’t know the date” — Home will ask for it later. If your periods are in the Astras cycle calendar, marking the conception day there sets the start date for you. Karina AI, if your plan includes it, can take answers like “about 6 weeks ago” or “I’m not sure”; when you’re unsure and a last period is logged, it counts from that period and says the date is approximate. Once your clinician gives you a date, update it with “Change the date.”
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Yes, if your plan includes Karina AI and you’ve allowed health-data processing. With your question, the chat receives your start date, the same completed weeks and days the card counts, trimester, estimated due date, the week’s “Baby” and “You” notes as general information, and your gestational age on the dates of your lab tests. Karina AI is software, not a person, and can be wrong. It doesn’t recommend medicines or supplements or their doses. If you describe something that may be an emergency, it tells you to contact emergency services instead of answering. Your doctor leads the pregnancy.
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Astras doesn’t sell your data for money, shows no ads in the app and sends nothing about your pregnancy to advertising or analytics platforms. The dates are stored in your account on our server, not only on your phone, so they appear on every device you sign in on. They reach AI services only with health-data consent: the dates when you ask Karina AI, and just “pregnant” with the trimester when Astras reads a lab report or writes Karina’s review, so the report’s pregnancy range can be picked. In Settings you can turn health-data processing off and keep the data, or turn it off and delete it — that erases the pregnancy dates together with the cycle calendar. You can also export everything or delete the account.
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Tap “I gave birth” — from 28 weeks 0 days on the card, or from 22 weeks 0 days in the “⋯” menu, with or without a plan. Astras asks “Has your baby been born?”, then lets you pick the birth date. Pregnancy mode ends and the calendar returns to cycle tracking: “Predictions will return once you log your first period.” Bleeding in the first four weeks after birth isn’t counted as a period, and the first new cycles get a wider forecast window. If you tap by mistake, “Pressed by mistake? Go back” leaves everything as it was. From then on, Karina AI receives only the birth date and how many days have passed.
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No — not on the website itself. The due date is calculated inside the app: at sign-up under the date ribbons, and on Home in the pregnancy card. The rule is simple enough to do by hand: take the first day of your last period and add 280 days, which is 40 weeks. For example, March 2, 2026 gives December 7, 2026, and on July 23, 2026 that pregnancy is 20 weeks 3 days. Any such date is an estimate; the date your clinician gives you is the one to plan around.
Your pregnancy, week by week
Completed weeks, trimester and an estimated due date from your last period — in the Astras app.