What is the due date if conception was on September 20?

Generally, if September 20 is the first day of the last menstrual period, the due date is usually around June 27 of the following year. However, this may vary slightly depending on the menstrual cycle and fetal development. If in doubt, it is recommended to consult a healthcare provider early. Detailed analysis is as follows:

If the pregnant woman has a regular menstrual cycle (approximately 28–30 days), calculating the due date based on the first day of the last menstrual period is relatively accurate—adding 9 months or subtracting 3 months from the month of the last period, and adding 7 days to the date. Starting from September 20, this results in a due date of June 27 the following year. In such cases, the actual delivery date typically occurs within 1–2 weeks of the estimated due date, which falls within the normal range.

If the menstrual cycle is irregular (e.g., longer than 35 days) or if the exact date of the last menstrual period is unclear, estimating the due date solely based on September 20 may lead to inaccuracies. In these situations, the due date should be adjusted according to early ultrasound findings. Ultrasound can determine gestational age by measuring fetal size, thereby refining the estimated due date to better reflect the actual fetal development progress.

After establishing the due date, regular prenatal checkups are essential to monitor fetal development and maternal health. As the due date approaches, watch for signs of labor, such as contractions and bloody show. Seek immediate medical attention if any abnormalities occur to ensure the safety of both mother and baby.