Why Your Abortion Provider Might Date Your Pregnancy Differently

You may have figured out how far along you are using an app, your own count, or a date you remember. Then your provider sends back a different number — often one that says you're a little further along. This can feel confusing or frustrating. Here's why it happens, and why the later date is usually safer for you.

How We Count How Far Along You Are

We count from the first day of your last period. This is what ACOG (the main group of OB-GYN doctors), the WHO, and almost every medical group around the world say to do. It's the standard your provider follows.

The only thing that can change that count is an ultrasound report from a clinic. The report needs to show the measurements and the dates the clinic figured out. If you have one, send it to us. We might use it to update how far along you are — dating guidelines only let us switch to the ultrasound's dates if they are a certain number of days different from the period-based count.

When the Date Isn't Clear

Real life is messy. Some people have irregular periods. Some can't remember the exact day their last period started. Some had spotting or light bleeding that they thought was a period but wasn't. So we often have to choose between two dates that both seem possible — say, one that puts you at 8 weeks and one that puts you at 10 weeks.

When that happens, we go with the later date. Here's why.

Why the Later Date Is Safer

The amount of misoprostol you need depends on how far along you are. Earlier in pregnancy, you need less. Later in pregnancy, you need more — often spread out over more than one dose, so the uterus fully empties.

If the later date is right (you're further along than you thought): You get the dose your body needs. That's the right amount.

If the earlier date is right (you're not as far along as the later date says): You took a little more misoprostol than you strictly needed. That's safe — extra misoprostol in this case is not dangerous.

Now flip it. What if we picked the earlier date and the later date was actually right? You'd be getting too little medicine. When the dose is too low, the abortion can be incomplete — meaning some pregnancy tissue stays inside. An incomplete abortion carries a real risk of hemorrhage — bleeding heavy enough to be dangerous and need emergency care. It can also lead to:

• Heavy bleeding that lasts longer than it should
• Needing more medicine
• Needing a follow-up procedure to finish the abortion

So the choice is not even. Going later trades a small chance of a stronger experience for a real drop in medical risk. Going earlier does the opposite — and that one has real risks.

When we're not sure, the safer choice is later.

"But I'm Sure of My Date"

Your information matters. We listen. Here are some things that often surprise people about how dating works:

• Apps guess; they don't measure. They use a typical cycle length and count back from there. That's a guess based on averages.
• Even regular periods change. Ovulation can shift by a week or more from one cycle to the next.
• Knowing when you had sex doesn't pin down the day of conception. People often ovulate days earlier or later than they think. Medical guidelines also don't allow us to use the day you had sex to figure out a due date — it's not accurate enough.

None of this means we don't trust you. It just means that without an ultrasound report, the safer move is to plan for the later date.

What This Looks Like in Practice

In a Southern Woven consult:

1. You tell us when your last period started and any other dating info you have.
2. A provider reviews your information and picks the dating that fits best.
3. If your date and ours are different, we usually go with the later one (unless an ultrasound report says otherwise).
4. The misoprostol dose follows that date.
5. You can always ask the provider to walk you through how they got there.

If you want to try estimating how far along you are yourself, our pregnancy calculator and our post on how far along am I? can help.

The Bottom Line

We're not ignoring your math. We're following a rule that doctors use everywhere — because dating is often unclear, and the risks of using too little medicine are bigger than the risks of using a little extra.

Safer, in this case, means we lean later.

Have questions about your dating? Start a free, confidential consultation or call 845-THE-PILL.

This information is for educational purposes and does not replace advice from a licensed healthcare provider. Reviewed by the Southern Woven Medical Team. Last updated: May 2026. Sources: ACOG Committee Opinion 700 — Methods for Estimating the Due Date; WHO Abortion Care Guideline 2022; Society of Family Planning clinical guidelines.