Twin: One of two children produced in the same pregnancy. Twins can develop from one ovum (egg) or from two ova (eggs). Twins who develop from a single ovum are called monozygotic or identical twins. They have identical genomes. Twins who develop from two ova that are fertilized at the same time are called dizygotic or fraternal twins. They are nonidentical and have different genomes.
Unfortunately, many women have a small amount of this hormone continuously and if the level gets high enough just before a period, you could get a false pregnancy test result. The best time to use a urine test for pregnancy is three to five days after your missed period.
1 A false positive pregnancy test means that your pregnancy test is positive but you are NOT pregnant. 2  A false negative pregnancy test means that you test negative but you ARE pregnant. Medications-Some drugs like Methadone, chlordiazepoxide, or promethazine can give a false positive pregnancy test.  2  Phantom-hCG 3  . The most important though very rare false positive blood test is a woman who has a low positive blood pregnancy test, the urine test is negative, and she is not pregnant.