1. How to calculate normal gestational age
For women who conceive naturally, gestational age is calculated as follows: gestational age is calculated from the first day of menstruation of the last menstrual cycle. Accordingly, the age of the fetus will be 14 days older than the actual age of the fertilized ovum (equivalent to 2 weeks).2. In-vitro fertilization (IVF)
In-vitro fertilization is a common assisted reproductive technique for couples experiencing infertility. This technique involves combining eggs and sperm in a laboratory environment rather than inside the female body as in natural conception.
In the laboratory, eggs and sperm are combined to form embryos. These embryos are then transferred back into the uterus of the woman, a process known as embryo transfer.
After being transferred to the uterus, the embryo begins to implant and develop normally, just like in cases of natural conception.
3. How to calculate gestational age after fresh or frozen embryo transfer
The IVF process can result in one or more embryos at a time. These embryos can be transferred back into the uterus, known as fresh embryo transfer, or frozen for future use, known as frozen embryo transfer.
SEE ALSO: How to calculate gestational age during in-vitro fertilization (IVF)
Typically, embryos are cultured in the laboratory for 2–5 days (embryo age) before being transferred back into the woman’s uterus. Thus, depending on the day of embryo transfer (embryo age), the gestational age calculation may vary slightly. The formula for calculating gestational age in IVF is as follows:
Gestational age in weeks = [(Current date - Embryo transfer date) + Gestational age at embryo transfer] / 7
Where:
Current date - Embryo transfer date: The number of days from the embryo transfer date to the current date.
Gestational age at embryo transfer = Embryo age + 14 days (the gestational age will be about 14 days older than the actual age of the fertilized egg/embryo). For instance: For a 2-day embryo transfer, the gestational age at transfer is 16 days. For a 3-day embryo transfer, it is 17 days. For a 4-day embryo transfer, it is 18 days. For a 5-day embryo transfer, it is 19 days.
The result for gestational age in weeks from dividing by 7 is interpreted as follows: the whole number represents the number of weeks, and the remainder represents the number of days.
For example, if the number of days from the embryo transfer to the current date is 10, and it was a 2-day embryo transfer, the gestational age at transfer is 16 days. Therefore, gestational age in weeks = (10 + 16) / 7 = 3 weeks and 5 days.
The calculation for frozen embryo transfers follows the same principle as fresh embryo transfers. The embryos are also cultured for 2–5 days in the laboratory before being frozen for transfer.
4. How to calculate due date when performing IVF
Similar to calculating gestational age in IVF, determining the due date depends on the day of embryo transfer (embryo age at the time of transfer, usually 2–5 days). The formula is as follows:
Due date in IVF = Embryo transfer date + X
Where:
X = 264 days for a 2-day embryo transfer.
X = 263 days for a 3-day embryo transfer.
X = 262 days for a 4-day embryo transfer.
X = 261 days for a 5-day embryo transfer.
Using the calculation above, expectant mothers can accurately determine the gestational age when transferring fresh or frozen embryos, as this method leaves little room for error. Hence, it is a widely trusted and applied approach to calculate gestational age in IVF.
The Vinmec IVF Fertility Support Center is a reputable destination for infertility treatment today. To date, the center has assisted over 1,000 couples with infertility issues, achieving a success rate of over 40%. This rate is comparable to that of developed countries such as the UK, the US, and Australia.
The center boasts a team of leading experts in obstetrics and gynecology, trained at top institutions worldwide in the US, Singapore, Japan, Australia, and renowned reproductive support centers globally.
With their high level of expertise and extensive experience, the specialists at Vinmec’s IVF Fertility Support Center can implement the most advanced reproductive techniques available today, helping hundreds of families across Vietnam achieve their dream of parenthood.
For more information about fertility support methods at Vinmec International General Hospital, please contact the Vinmec healthcare system nationwide or book an appointment online.
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