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When Did I Conceive?

by Katlyn Joy | May 12, 2011 12:00 AM
63 Comments


While actual dates of conception are difficult to determine because of the number of biological unknowns, it generally is fodder for conversation or guesstimating. However, it's fun to try to find out if it happened that long weekend in the mountains or when you made up after that silly fight you had over cleaning out the garage.

Conception Math

  1. Take the date of your last menstrual period. You count this as the first day of your last period, by the way.
  2. Add 12 days to this date as this is an average range of when ovulation would occur in the typical menstrual cycle.
  3. Add another 10 days to this date and highlight those 10 days. Which of those days were you and your sweetie getting busy? If only one time in that stretch did you have intercourse, you have found your likely conception date.

Those who practice fertility charting and chart their temperatures have been seriously working at getting pregnant probably know when they most likely ovulated during their cycle by looking at the records of basal body temps and observations of their cervical mucus. Women who have predictable cycles have an even better likelihood of knowing when they actually got pregnant. Additionally, those who chart usually also keep track of the dates they had sex.

Factors that Throw Off the Calculations

Women who recently stopped taking birth control pills or used hormonal methods for birth control may not have resumed a regular cycle yet and will have difficulty pinpointing the time of ovulation. Also, those who don't have regular periods or are not the best record-keepers of when cycles occur will be at a definite disadvantage than other expectant mothers when trying to determine when baby was made.

Sperm Facts

Of course, while the egg is the focus of attention here, let's not forget that crucial ingredient to baby-making; sperm! Sperm can throw off calculations by virtue of the simple fact that they don't live just a day in many cases. Indeed, sperm can often survive a day or two, and may live up to five days. So while you may have had sex only one time in the week you conceived you may not have gotten pregnant the day you had sex. It may have occurred a couple days later.

Couples who have more sexual activity together may have a more difficult time determining the day of conception. If they only had sex once that month, well it doesn't take a special formula to determine the special time. However, couples that are more amorous have more possibilities to consider.

Hard Facts

Even with a completed chart of temps, mucus observations, dates of when sex occurred, and the last menstrual period it can be impossible to pinpoint the exact moment of conception.

Early ultrasounds coupled with the firm date of the last period however can nail down a fairly precise due date, and a corresponding likely date of conception. However, the technology is less precise as the pregnancy progresses and a baby who grows at a different than typical pace can throw off results as well.

If you and your partner are beginning the baby-making adventure and you want to know when you achieved your goal, keep careful records of your periods and keep a sex calendar as well. Consider an ovulation predictor test as well to help with more exact date. There are plenty of online due date calculators, which in reverse determine your date of conception, as well. Plus, consider some storyteller liberties when talking of that special night when you two became a family.

Implantation Calculator - Find out when implantation occurred

Ovulation Calculator - Find out when you ovulated

How is Pregnancy Due Date Calculated?


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Comments


Showing 1 - 10 out of 57 Comments
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Lisha Aug 21, 2017 08:09:08 AM ET

I had my period on the 8th july and it stopped on the 11th so i had unprotected sex with my partner from the 20th till the 1st of august then i was tested positive on the 12 of this month. when did i conceive?

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Vivian Aug 17, 2017 04:33:33 PM ET

I had sex on 03-12-2016. after that i got my period then broke up with my boyfriend. i slept with another one on 3rd of january2017 untill today, we still have fun, now i am 34weeks and 6days pregnant and i can't tell who is the father.

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Tracy Aug 4, 2017 01:18:33 PM ET

If my due date is 11th october ,how old is my pregnancy now?

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Rebecca Jun 22, 2017 10:59:33 AM ET

My baby was born 20/03/2017. so when did i conceive? please help.

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Guest Jun 13, 2017 04:25:18 PM ET

I dated the first man the first days of my fertility, the days that i was likely to conceive. i dated another man the last day of my fertility days... who is really the father?

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Nancy Apr 28, 2017 09:04:27 PM ET

I had sex on 24th november 2016 when is my baby's due date?

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Guest Mar 6, 2017 12:46:35 AM ET

I gave birth on the 06-01-2017 so when did i conceive?

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Guest Mar 6, 2017 12:45:36 AM ET

I had a cesarean birth on the 06-01-2017 so when did i conceive

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Karla Jan 18, 2017 05:41:01 AM ET

My due date is 21/6/17 but i had sex on the 7th september then had a period of 2-3days on the 13th september then i had sex again on the 23rd september i really need to know wen i conceived.

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kim Dec 26, 2016 07:40:04 PM ET

8weeks pregnant, when did i conceive?

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