There are different reasons which might make the parent or parents of a child want to calculate due date from conception or even get the conception date from birth date. The reasons warranting such an investigation might either be due to pure curiosity or to serve as a proof to the right paternity of a given child in cases where the mother had multiple sexual partners.
Most parents who want to calculate their due date from the conception date or vice versa can use conception calculators that are easily available on the Internet or do their calculations based on the fact that the human gestation period is about 40 weeks. It however is important to emphasize that this is usually a guess since gestation can take more or less the stipulated time.
In case you are more keen in trying to identify who the actual parent of your child is when you calculate due date from conception, it will be important that you keep your mind fresh about who you had unprotected sex with and at what time of the month. This is very important so that you can identify which potential father lies in the resultant fertilization window.
However, the results of these tests can prove really useless if you had sex with different partners during you fertility window. This is because the sperms of a human being can remain potent in a female body for up to five days and a mix up of sperm from different people will only make the matter more complicated. In such situation, more advanced identification methods are needed.
Possible replacements to the calculate due date from conception technique will include blood group matching where the blood group of your baby has to be in a way related to that of the possible father. In case such a test leaves you with multiple answers, the last and most accurate resort will be going for a gen typing test.
The name of the test should give you the answer at the start. It is meant to estimate the due date from conception not vice versa. The ability to invert it exists, but will only work after the date of birth of the baby has been established by the actual birth of your baby.
In addition to this, the 'calculate due date from conception' escapade will either be frustrating or a total joke in cases where the exact date of conception is unknown to either of the parents. This is very common since having sex in a given day does not mean that is the day you conceive. This is another factor that adds to the randomness of the results of such calculations making them only but approximations rather than exact findings.