HealthTap Online Primary Care Doctors Accepting New Patients
Book a video visit
HealthTap
Telehealth
A member asked:

When sonograms are done in 2nd and 3rd trimesters, are those based on lmp or by growth? i'm trying to figure conception date

A doctor has provided 1 answer

Earliest due date: The due date is based on the first day of the last menstrual period and confirmed or changed based on the earliest ultrasound. Ongoing ultrasounds are based on the LMP due date or earliest ultrasound due date. So use your due date to find possible date of conception - google an app for that.

Dr Samuel agreed

Answered 9/15/2020

5.3k views

Thank

Related Questions

A member asked:

My lmp was Feb 8-12. My due date was Nov 23.(calculated by my first sonogram).My Obgyn informed me my conception date was Mar 2. I had intercourse on Feb 20th and Feb 27-28. What would be sexual intercourse that would had led to my conception date ?

A doctor has provided 1 answer

A member asked:

When a doctor says margin of error is 3-5 days in first trimester us are they talking about lmp, due date, or conception date?

A doctor has provided 1 answer

A member asked:

I'm due aug 30th according to ultrasound at 12 weeks, 1st ultrasound at 6 weeks said due date aug 29th, my LMP nov 18 need my conception date range :)?

4 doctors weighed in across 2 answers

A member asked:

Why does my ultrasound and lmp match to the exact date? Do ultrasound measure from conception?

A doctor has provided 1 answer

A member asked:

How accurate is an early ultrasound? On 6/15/18 baby measured 5w6d. Between what dates could conception of happened? LMP 5/5.

A doctor has provided 1 answer

Sponsored Content
HealthTap Medical Group does not endorse products or services. Sponsored content revenues support our mission to make health information free and accessible to all.Learn more

People also searched for:

How accurate are second and third trimester sonogram measurements in figuring date of conception?
Based on an estimated LMP from an eight week ultrasound to be 10/15/12, what is the very latest possible date conception could have occurred?
1st ultrasound says crl 8mm 6w5d. 2nd says crl 28mm, 9w4d. 3rd , crl 60.9mm 12w4d.Are these supposed to date back to lmp? When was conception?
Dated 12 weeks 4 days on 7th Aug (first trimester), no lmp, how accurate is CRL? and is this age from conception?
LMP was Feb 18, I have shorter cycles of 25/26 days. 3 first trimester ultrasounds gave me a due date of Nov 19-21 putting conception at Feb 27-29. How accurate are these conception dates? Anyway conception occurred before February 20?

Telemedicine

Primary Care
Manage Your Conditions
Women's Health
Children's Health
Men's Health
Senior Health
Wellness, Prevention & Lifestyle
Sexual Health
Mental & Behavioral Health
Travel Medicine
Urgent Care
Ask your question
Didn't find what you're looking for?

90,000 U.S. doctors in 147 specialties are here to answer your questions or offer you advice, prescriptions, and more.

Ask your question

More of what we treat

Allergies
Antibiotics
Asthma
High Blood Pressure
Prescriptions
Type 2 Diabetes
Content on HealthTap (including answers) should not be used for medical advice, diagnosis, or treatment, and interactions on HealthTap do not create a doctor-patient relationship. Never disregard or delay professional medical advice in person because of anything on HealthTap. Call your doctor or 911 if you think you may have a medical emergency.
HealthTap
HIPAA logo
HIPAASecure
Soc 2 Type 2 logo
SOC 2 Type 2Certified
JCAHO Accredited
JCAHOAccredited
Member App

Download HealthTap

Video visit and message your doctor

Member App QR Code
Play Store Member LinkApp Store Member Link

Questions?

+1 (888) 828-0841support@healthtap.com
LinkedInTwitter
HomeTermsPrivacyCookiesDMCAHealth TopicsDoctors DirectoryDoctor Q&A by Specialty
Copyright 2026 HealthTap, Inc.