Your Pregnancy, Week by Week — Now With a Calendar Nobody Else Has Built
The best and most precise online pregnancy calendar. By an ObGyn. Evidence-Based. Integrates with your personal calendar. Better than any app.
A patient once told me she spent more time reading pregnancy apps than sleeping. She was not exaggerating. She had three apps on her phone, a browser full of open tabs, and a growing sense that none of it was giving her real information — just the same recycled sentences dressed up in different fonts. “How many weeks am I?” should have a simple answer. It rarely does.
I built something different. It is called the ObWeekly Pregnancy Week-by-Week Calendar, it lives at tools.obmd.com, and it does something I have not seen anywhere else: it gives you a permanent, shareable link to your exact pregnancy — and it puts every week of your pregnancy directly into your Google or Apple calendar.
What It Is
The ObWeekly Pregnancy Week-by-Week Calendar is a free, evidence-based clinical tool.
You enter your due date — that is all — and the tool calculates your entire pregnancy in exact clinical terms. Not “you are in your fourth month.” Not “baby is the size of a mango.” Those phrases have no clinical meaning. The tool uses gestational age the way ObGyns and midwives use it: in weeks and days,
Not from the first day of your last menstrual period. Because that is often incorrect.
But by calculating back from your due date. The Most Precise way to know your weeks and days.
There are several ways to calculate your due date, and you can do it in the ObMD Due Date Calculator.
Every week from 4 to 42 is displayed with what is actually happening: fetal development, body changes, evidence-based warning signs, and guidance on when to call your provider. Tips to improve pregnancy outcome.
The content comes from peer-reviewed sources and current clinical guidelines — not from wellness bloggers. And it is updated regularly with new evidence.
The Feature Nobody Else Has: A Permanent Link to Your Pregnancy
When you enter your due date, the tool generates a URL that is specific to you, to your estimated due date (EDD) — and that URL never changes. It encodes your due date directly into the web address. No account. No password. No login. No app to download. No privacy policy to scroll past.
This means you can bookmark it once and come back to it every week — and it will always open on your current week. It means you can share the link with your partner, your mother, your doula, your ObGyn — and everyone is looking at the same calendar, the same information, the same clinical week. It is not a screenshot. It is not a PDF. It is a live, working page that anyone with the link can access at any time from any device.
You can add it to your home screen like an app.
No app does this. Most pregnancy apps are built around accounts, subscriptions, and data collection. This tool collects nothing. The URL is the product.
The Calendar Feature: Something Genuinely New
This is the part I am most proud of, and as far as I know, no pregnancy tool has done it before.
The tool generates a complete pregnancy calendar file — in the standard ICS format used by every calendar application in the world — and lets you add all 38 weeks to your Google Calendar or Apple Calendar in a single step. Each week becomes a calendar event. Each event contains the clinical description for that week: what is developing, what to watch for, what is normal.
Your pregnancy is no longer just on your phone in an app. It is in your calendar, alongside your work meetings and your prenatal appointments, visible at a glance, automatically in the right week.
Absolutely right. Creating a dedicated calendar first is the correct workflow — it keeps all 38 weeks organized, lets you show/hide the pregnancy calendar independently, and avoids cluttering the main calendar.
Google Calendar: Adding Your Pregnancy Weeks
Step 1 — Create your ObWeekly calendar (do this first)
On a computer:
Go to calendar.google.com
In the left sidebar, find “Other calendars” and click the + sign
Select “Create new calendar”
Name it ObWeekly and click Create Calendar
On Android or iPhone: Calendar creation is not available in the mobile app. Complete Step 1 on a computer first. ObWeekly will then appear automatically in your app.
Step 2 — Import your pregnancy calendar
On a computer:
Click the + sign next to “Other calendars” again
Select “Import”
Choose the .ics file you downloaded from the tool
In the calendar dropdown, select ObWeekly
Click Import — all 38 weeks load at once
On Android:
Download the .ics file to your phone
Open the file from your Downloads folder — Google Calendar will recognize it and offer to import
When prompted, select ObWeekly as the destination
If it does not open automatically: open the Google Calendar app > three-line menu > Settings > Import
On iPhone (Google Calendar app):
Download the .ics file
Tap the file to open it
When prompted, select ObWeekly as the destination
If Google Calendar does not open automatically, tap Share on the file and choose Google Calendar from the share menu
Apple Calendar: Adding Your Pregnancy Weeks
Step 1 — Create your ObWeekly calendar (do this first)
On Mac:
Open the Calendar app
From the menu bar: File > New Calendar
Name it ObWeekly and press Return
On iPhone or iPad:
Open the Calendar app
Tap Calendars at the bottom of the screen
Tap Add Calendar in the lower left
Name it ObWeekly and tap Done
Step 2 — Import your pregnancy calendar
On Mac:
Double-click the downloaded .ics file
Apple Calendar opens and asks which calendar to use
Select ObWeekly and click OK — all 38 weeks import immediately
On iPhone or iPad:
Open the Files app and find the downloaded .ics file
Tap the file
When prompted, select ObWeekly as the destination and tap Add All
If the file does not open: tap and hold the .ics file > Share > Open With Calendar
Sharing the Pregnancy Timeline
We made it easy to share your pregnancy timeline. All you need to do is copy the URL of your due date (EXAMPLE: 12/31/2027) like this format yyyy/mm/dd: https://obweekly.obmd.com/?due=2027-12-31
Anyone you share this with will be able to follow your timeline. And they can add it to THEIR calendar.
Why This Matters Clinically
Pregnancy apps have a fundamental problem: they require active engagement. You have to open the app, remember to open the app, and find the right screen. Most patients do not do this consistently — and when something concerns them, they often cannot locate the relevant information quickly.
A calendar event is passive. It arrives. It is already in the workflow patients use every day. When week 28 begins, the event is there in their calendar — with the clinical information for week 28, including the signs that warrant a call to their provider. They did not have to go looking for it.
The tool does not replace prenatal care. It is not designed to. It is designed to help patients understand what is happening week by week, in plain language, using accurate clinical terminology — so that when they do see their provider, the conversation is better.
My Take
The pregnancy app market is enormous, and nearly all of it is built around engagement metrics, subscription revenue, and data collection. The tools that are free are often free because you are the product. This tool is different. It is a one-time interaction: enter your due date, get your calendar, use it for nine months. No account, no tracking, no subscription.
The shareable URL is not a gimmick. Pregnancy is not a solo event. Partners, family members, and care team members all benefit from having access to the same evidence-based information. A single link solves that. The calendar integration goes one step further: it makes pregnancy information ambient rather than on-demand. For patients who are already overwhelmed, that distinction is real.
I built this because I was tired of seeing patients arrive to appointments with conflicting information from three different apps — none of which cited a single source. Fifty years of obstetric practice is a lot of information to distill. This tool is one attempt to do it honestly.
Try it at tools.obmd.com. Enter your due date. Share the link. Add it to your calendar. Then tell me what I missed.
Amos Grunebaum, MD | Professor of Obstetrics & Gynecology | Maternal-Fetal Medicine | obmd.com