How to find out the day i conceived

“When exactly did I get pregnant” is a difficult question to answer precisely because calculating conception is done by using the first day of your last menstrual period or an ultrasound date.

Use our Pregnancy Calculator to calculate these dates for you.

Calculating Gestational Age

Last Menstrual Period

If the mother has a regular period and knows the first day of her last menstrual period, gestational age can be calculated from this date. Gestational age is calculated from the first day of the mother’s last menstrual period and not from the date of conception. A pregnancy wheel is often used to calculate gestational age.

Ultrasound

 The baby can be measured as early as 5 or 6 weeks after the mother’s last menstrual period. Measuring the baby using ultrasound is most accurate in early pregnancy. It becomes less accurate later in pregnancy. The best time to estimate gestational age using ultrasound is between the 8th and 18th weeks of pregnancy. The most accurate way to determine gestational age is using the first day of the woman’s last menstrual period and confirming this gestational age with the measurement from an ultrasound exam.

Calculating Conception Date

In a Typical Pregnancy

For a woman with a regular period, conception typically occurs about 11-21 days after the first day of the last period. Most women do not know the exact date of conception because it can be challenging to know exactly when ovulation occurs. Thus, their conception date is merely an estimate based on the first day of their last period.

Special Cases

Women who undergo special procedures, such as artificial insemination or in vitro fertilization, typically know the exact date of conception.

Calculating Estimated Due Date

Based on the last menstrual period, the estimated due date is 40 weeks from the first day of the period. This is just an estimate since only about 5% of babies are born on their estimated due date.

Difficulties in Determining the Gestational Age

Last Menstrual Period

For women who have irregular menstrual periods or women who cannot remember the first day of their last menstrual period, it can be difficult to determine gestational age using this method. In these cases, an ultrasound exam is often required to determine gestational age.

Baby’s Growth

In some cases, it is difficult to determine the gestational age because the baby is unusually large or small. Also, in some cases, the size of the uterus in early pregnancy or the height of the uterus in later pregnancy does not match the first day of the last menstrual period. In these cases as well, it is difficult to obtain an accurate gestational age.

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Can I know the exact day I got pregnant?

Knowing the exact day of conception is a difficult thing. Sperm can live in a woman's body for up to five days, making it impossible to calculate exactly when conception occurred. It is not a fine science. In addition, women ovulate anywhere from 11 to 21 days after the first day of their last period.

How do I know the first day I conceived?

The first sign of pregnancy is usually missing a period, about 2 weeks after you've conceived. This isn't always reliable and if your periods aren't regular you might not notice you've missed one. Some women have a bit of bleeding as the egg embeds. Many women also experience tender breasts.