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.
The presence of any impurities in your urine sample may also cause a false positive pregnancy test. It could happen when the sample is contaminated with detergent, soap, or even blood. Not cleaning the cup that comes with certain pregnancy test kits can also cause contamination of the urine sample and affect your results.