Elena Gilbert in the books does not have children,as in the series.So,maybe you thought of Nina Dobrev who plays Elena in the series - no she hasn't got any children.
The uterus is part of a woman's reproductive system that is located in the pelvis between the bladder and the rectum. The uterus is the hollow, pear-shaped organ where a baby grows. The narrow, lower portion of the uterus is called the cervix. The broad, middle part of the uterus is called the body, or the corpus. The dome-shaped top of the uterus is called the fundus. The fallopian tubes extend from either side of the top of the uterus to the ovaries.
30 - 60 minutes: Sperm can pass through uterus into fallopian tube in as little as 30 minutes ; fertilization can take place in less than an hour from entry thru the cervix. This is length of time sperm normally spends in uterus. Fertilization takes place in fallopian tubes ; embryo inplants in the womb.