Try to calculate the day of pregnancy. With regular cycle length 28-30 days, the egg Matures in approximately two weeks from the start of the last menstrual period. If in this period, sexual intercourse was only with one of the men, with high probability it can be considered the father of the child. However, under the influence of various factors ovulation may be delayed or, conversely, to happen ahead of time, so 100% guarantee this way you will not give.
Try to understand, who looks like a child. Pay attention not only on the obvious signs like hair color and skin, but also on traits such as eye shape, oval face. Well, if you have the opportunity to see baby pictures of the partners and their relatives. However, this method is the least reliable, as the child is not always an exact "copy" of the parents.
In some cases, to determine the paternity of the child possible blood group. She inherited according to certain laws. For example, if you and men the first group, the baby cannot have any other. The combination of the first and second also does not give any other options. However, this method will not work if you have and men, for example, the second and third blood group. In this case, the child can get any one of the four groups. The method is also useless if both partners are of the same blood group.
The only 100% (or 99,9%) accurate method of determining paternity is the DNA. The studies will use any biological material of the child and the potential father: blood, saliva, hair, etc. in addition, therefore, it is possible to know the answer even before the birth of the baby. However in this case, to obtain the biomaterial of the child the woman must decide on quite complex procedures: chorionic biopsy, amniocentesis or cordocentesis. The disadvantage of this method is the relatively high cost, but only with his help can finally dot the i.