The Conception Calculator

Due Date April 7: When Did You Conceive?

Due dates & conception. Updated . Calculated with the standard pregnancy dating method used by ACOG and the NHS.

If your baby is due on April 7, conception most likely happened around July 15 of the previous year. Here is how that date is worked out and the range of days it could realistically fall on.

Key dates for a April 7 due date

Most likely conception dateJuly 15
Likely conception windowJuly 12 – July 18
Days when sex could have led to pregnancyJuly 10 – July 16
Estimated first day of last periodJuly 1
Positive home test likely fromJuly 29 (around the missed period)
Second trimester begins (14 weeks)October 7
Third trimester begins (28 weeks)January 13
Full term begins (39 weeks)March 31

How the conception date is calculated

Due dates are normally counted as 280 days (40 weeks) from the first day of the last menstrual period. In a typical 28-day cycle, ovulation and conception happen about two weeks after that period starts, so conception sits roughly 266 days before the due date. Subtracting 266 days from April 7 gives July 15.

Sperm can survive in the reproductive tract for up to five days, while an egg lives for about 12 to 24 hours after ovulation. That means sex several days before ovulation can still lead to pregnancy.

How certain is this date?

Only a small share of babies, often quoted at around 4 to 5 percent, arrive on their exact due date, so dates worked backwards from a due date carry a margin of a few days either way.

If your cycles are usually longer than 28 days, conception probably happened a little later than July 15; with shorter cycles, a little earlier. A cycle that is 32 days long, for example, shifts the likely date about four days later.

Check your own dates

Enter your exact due date in the conception date calculator to see these results with weekdays and the correct year, or start from your last period with the last-period conception calculator.

Conception Date Calculator: Find the most likely conception date from your due date.

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This article is general information, not medical advice. Talk to a doctor or midwife about your own pregnancy or fertility.