Forty weeks, translated
Crimson is a free pregnancy tracker app for iOS and Android that turns each week into something you can actually picture. Switch to pregnancy mode and your home screen becomes a week-by-week timeline: how far along you are, what's developing right now, and a size comparison that makes it real. One week it's a raspberry. Later it's a cantaloupe. Abstract dates become a story you can follow.
The timeline is more than trivia. Each week comes with plain-language notes on what's happening with your body and your baby, so the weird stuff — the round ligament twinges, the sudden aversion to coffee — has context. And because Crimson started as a fertility and ovulation tracker, your cycle history carries over. The app already knows your dates.
Tools for the third trimester (and the anxious second)
Kick counter
Count movements in timed sessions and keep a history you can look back on. Many providers suggest starting kick counts around week 28 — Crimson makes each session a few taps, so you're counting kicks, not watching a clock.
Contraction timer
Tap when a contraction starts and stops. Crimson logs duration and the gap between them, so when you call your birth team you have real numbers instead of "I think they're getting closer?"
Appointment tracking
Keep every prenatal visit, ultrasound, and glucose test in one place, alongside everything else you're logging. No more digging through portal messages for a date.
Weight tracking
Log weight entries over the course of your pregnancy and see the trend at a glance. Useful context for appointments, and one less thing to remember on the spot.
A PDF report your doctor will actually read
Prenatal appointments are short, and memory is unreliable at 8 a.m. in a paper gown. Crimson generates a PDF pregnancy report from your logged data — kick sessions, contractions, weight, symptoms — so you can hand your provider a clean summary instead of reconstructing the month from scratch. Need the raw numbers? CSV export with date filtering is built in too. Both are free.
An AI that knows what week you're in
Crimson's AI assistant works out of the box — no API key, no setup. Ask it about a symptom and it answers with your pregnancy week and logged history in mind, not generic web copy. Free accounts get a daily AI allowance. Crimson Pro makes AI unlimited, and every new account starts with a 14-day Pro trial so you can see the difference yourself.
Wondering how Crimson stacks up against the big names? Our period and pregnancy app comparison lays it out, feature by feature, including the pricing the other apps bury.
Private by design
Pregnancy data is some of the most sensitive information there is. Crimson stores your data locally on your device first, then syncs it to the cloud so it follows you across devices — encrypted in transit (TLS 1.2+) and at rest. We never sell your health data, and there are no ads. A free account is required; that's what keeps your history safe when you switch phones. Questions about any of this? Talk to us.
Straight talk: Crimson is an educational tracking tool, not a medical device, and nothing in it is medical advice. It doesn't replace prenatal care, and no app can. If something feels wrong — bleeding, severe pain, reduced fetal movement — contact your provider or seek urgent care. Trust your body over any app, including ours.
Frequently asked questions
Is Crimson's pregnancy tracker free?
Yes. The week-by-week timeline, kick counter, contraction timer, appointment tracking, weight tracking, PDF reports, and CSV export are all free. Crimson Pro is an optional subscription that adds unlimited AI, and every new account starts with a 14-day Pro trial.
When should I start counting kicks?
Many providers recommend starting regular kick counts around week 28, though yours may suggest a different timing based on your pregnancy. Crimson's kick counter logs each session so you can spot your baby's normal pattern and share it at appointments.
Can Crimson tell me if I'm in labor?
No. The contraction timer records how long contractions last and how far apart they are, so you have clear numbers to give your provider or birth team. It cannot diagnose labor. If you think something is wrong, call your provider or go in — don't wait on an app.
Do I need an account or my own AI key?
You need a free Crimson account, which keeps your data synced across devices. The AI assistant works out of the box with no API key to configure — free accounts get a daily AI allowance, and Pro makes it unlimited.
Still in the trying-to-conceive stage? Start with our fertility tracker, and brush up on the basics in the cycle tracking guide. Crimson carries your history into pregnancy mode when the time comes.
Track your pregnancy with Crimson
Free week-by-week tracking, kick counter, contraction timer, and PDF reports. Private by default. Pro unlocks more.