Estimating Date of Conception

Question

How can my fertility doctor be sure I conceived on May 14? My period started on April 30. My six week five day ultrasound showed the baby at 7.5mm and my 7W5D ultrasound showed the baby at 14 mm. He isn’t dating my pregnancy from my LMP. How can he be sure I didn’t conceive on May 11 for example? I have had fertility problems for a long time and I don’t know how he can tell if I ovulated early or not.
Alicia

Answer

Last Updated: January 31, 2022
Dear Alicia,

Thank you for visiting our web site, and contacting us. The ultra sound measures and observes the development of your baby. Remember sperm can live up to five days in the woman’s body before ovulation. It is possible you had intercourse on May 11 but didn’t conceive until May 14. Your doctor can give you a good estimate of when you conceived based on the baby’s development. It is a more accurate way than from the LMP because the timing of ovulation can vary. If you learn a Natural Family Method of charting your daily menstrual events, you will be able to recognize the time of ovulation, the days you are fertile and the days you are infertile in each cycle. This will give you an accurate way of dating the beginning of your next pregnancy. If you keep a daily chart, your fertility problems can be diagnosed and treated more easily, as well. NFP teachers in California are listed on this web site.

Judy Wilmurt

Answered By:

Judy Wilmurt
Judy Wilmurt, Professional Member of CANFP, and past member of the Executive Board, taught the Creighton Model FertilityCare System of NFP in the Oakland region, wherre she resides with her husband Eric.

Read more related questions

Stressed I Might Be Pregnant

I am really stressed. I just got out of a four year relationship and I am worried I might become pregnant. No symptoms but it…

Is Progesterone Supplementation Moral?

I am currently 28 weeks pregnant with my second child. My first was born premature. My ob suggested progesterone injections starting at 16 weeks through…

Are Fibroids Causing Bleeding During Pregnancy?

Hello, I am 45 years old and have large fibroids. I was about to have surgery to remove the womb. I am now seven weeks…

Progesterone in Pregnancy—History of Miscarriage and Pre-Term Delivery

We are seven weeks pregnant after trying for over a year. We miscarried last year after being on Prometrium for low progesterone and infertilty (infertile…

Scared I Am Miscarrying

I am writing because I am 13 weeks pregnant by ultrasound and LMP (but 11 weeks by my chart). This is my 4th pregnancy, I…

Scared Progesterone Can Harm My Baby

I am 32 years old and this is my first pregnancy. I have never had a miscarriage but when I started bleeding (hematoma) at 12…

Should I Stop Nursing Since Pregnant

I am four weeks pregnant with my third pregnancy and still nursing my nine month old pretty frequently. I am 30. I nursed during my…

Desperate for Explanation of Brown Spotting

I had sexual intercourse with my boyfriend and I am currently age 22. I finished my period on March 10th and the last time I…

Is My Progesterone Too Low for 15 Weeks Pregnant?

I am 42 years old and 16 weeks pregnant. I have had four first trimester losses (before nine weeks). I am MTHFR compound hetero (C677…

Did I Conceive May 11th or May 12th?

I was reading thru questions asking about “Who is the father?” One of the questions asked seemed very similiar to the situation that I’m going…

Did Progesterone Contribute to Baby’s Brain Cyst?

Hi, I was wondering about your knowledge on choroid plexus cysts. There were three found on my baby’s brain at my 19 week sonogram. I…

Estimating Date of Conception

How can my fertility doctor be sure I conceived on May 14? My period started on April 30. My six week five day ultrasound showed…

Create An Account

This is not a membership, this is an account for our CANFP website. If you decide you would like to sign up for one of our memberships later, you can do so with or without this account.

First Name *
Last Name *
E-mail *
Username *
Password *
Confirm Password *
Edit Profile
Information
Subscriptions
Payments
Order History
Downloads
Shipping and Billing
Donations
Settings
Login Information
Notification Settings
Notification Subscriptions
Profile

CANFP conducts varied outreach programs to the community at large, in addition to serving our members (NFP users, teachers, and advocates).

CANFP provides education programs tailored to the audience, not only on Natural Family Planning, but on the wide variety of topics related to it.

Programs can be continuing education for NFP Professionals, introductory information for a lay audience of youth or adults new to the topic, or specifically tailored to the interests of a professional audience, such as educators, physicians, or clergy. Content is faith based or secular, whichever is suitable for situation.

CANFP offers a variety of resources for those just discovering Natural Family Planning, as well as to meet the varied needs of our CANFP Members. Most resources are available to any visitors to our site. Some resources do ask you to register as a site user in order to access them, others are available only to CANFP Members.

CANFP statewide conferences, regional events offered in collaboration with local partners, events featuring CANFP speakers, or exhbit, as well as other events throughout the state of interest to our NFP community.  Come meet one of our experts at one of these events or book a speaker for your own upcoming event.

CANFP depends on the gifts, talents, and generosity of our members and supporters. The success of our mission depends on the collaboration of our members. Please consider contributing your time treasure and talent through CANFP to share the good news of NFP with the world! Both volunteer and contracted positions available.

Stay informed by joining our email list

* indicates required
Which role(s) best describes you?