Whenever you have questions such as this, I would suggest that you schedule an appointment with your primary care physician
. The two of you can discuss health issues such as this in a confidential setting. The short answer to your question is no, this cannot happen. There is virtually no chance for anyone to get pregnant from sitting on the toilet that had been soiled with semen. This of course is especially true when it has been cleaned up with soap and water or when it has been more than a few hours since the ejaculation. In order for a sperm to end up resulting in a pregnancy, it must be initially propelled into the back of the vagina. Sperm cannot survive outside the male body or the female uterus for long periods of time. Even if the semen was not cleaned up, it is almost inconceivable that it would somehow end up making its way into a woman's vagina and up to the cervix all while staying healthy enough to make the swim up the uterus into the fallopian tubes for conception. Another common question is whether ejaculation into a shared tub can result in pregnancy. This too is an unlikely occurrence. Again, please discuss your concerns with your primary care physician. Good luck.